Pre-release monitoring of play behaviour and relationships in a group of orphaned chimpanzees (Pan troglodytes troglodytes) at the H.E.L.P. Congo sanctuary and release site

Dissertation Course Name: Module P20107 – Final Project Title: Pre-release monitoring of play behaviour and relationships in a group of orphaned chimpanzees (Pan troglodytes troglodytes) at the H.E.L.P. Congo sanctuary and release site Student Number: 09090772 Surname: Khoshen Kraselnick Other Names: Halit Course for which acceptable: MSc in Primate Conservation – SS85 Date of Submission: 17 September, 2010 This dissertation is submitted in part fulfilment of the regulations for an MSc degree. Oxford Brookes University

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Pre-release monitoring of play behaviour and relationships in a

group of orphaned chimpanzees (Pan troglodytes troglodytes)

at the H.E.L.P. Congo sanctuary and release site

Halit Khoshen Kraselnick

09090772

School of Social Sciences and Law

Primate Conservation MSc Candidate

Oxford Brookes University, Oxford, UK, OX3 0BP

September 17th, 2010

Word count: 14,898

Khoshen Kraselnick, 09090772 Play and relationships in pre-released orphaned chimpanzees

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Abstract ___________________________________________________________________ The last decades have seen many primate release initiatives come into place, most

of which with low to average success rates. Why do some individuals not cope or

survive in the wild may have been answered if more in-depth behavioural and social

monitoring would have been performed and documented during pre-release stages.

The current study took place over a period of 11 weeks, in which species-specific

behaviours and relationships of a group of pre-released pre-adult orphaned

chimpanzees at H.E.L.P. Congo were analysed, and behavioural problems were

identified. This was done through the analysis of play behaviour and proximity

distances during different activities. There was no overall difference in play

behaviour between the orphaned chimpanzees and chimpanzees living in wild troops

or in captivity where both mothers and adults are present. The orphaned

chimpanzees are likely using play for both short- and long-term benefits. ‘Normal’

advances in motor, tool and social skills acquisition were observed. The group is

cohesive and individuals posses good metacommunication and social perception

skills. Most individuals maintain strong relationship bonds with all of their peers,

although differing in quality and form. Only one dyad presented an unfriendly

relationship. One individual presented low social communication skills and

behaviours and high occurrence of stereotypes. Nonetheless, her sociality has

improved and her stereotypical behaviours have decreased over the years.

Relationships may change over time, especially due to age increase and should be

analyzed over the years. Post-release monitoring should be performed in order to

view if play behaviour, relationships and individual personalities can lead to insights

over survival, interactions and success after full-release. If so, this method will render

release initiatives able to predict more accurately future outcomes during pre-release

monitoring, as well as react on time in order to modify specific unwanted/needed

behaviours.

WC: 297


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Acknowledgements ___________________________________________________________________ I would like to thank Aliette Jamart for accepting me at H.E.L.P. and making sure I

had all I needed during my stay. For your deep passion in aiding orphaned

chimpanzees be free again while swimming against the current. To Benoit Goossens

for his aid in deciding on an appropriate topic for my dissertation. To Marie Vimond

for helping me get several last minute references when I was most busy with the

write-up, and in helping me figure out statistical tests when my head was exploding.

To Noël Kiyindou, Alain Banzouzi and Eric Loubassou for allowing me to invade their

forest camp, and for their support on and off observation hours. An additional special

thanks to Noël for helping me reacquaint with the girls, for his invaluable guidance in

the forest and for his constant protection of my hair from Clandestine’s mischievous

pulling. I might have not gotten back in one piece if it were not for you! To Bianieffe,

Clandestine, Dolly, Mila, Pattex and Youbi, for allowing me to invade their private

lives and accepting me in peace.

To Corri Waitt, my supervisor, for all her patience, guidance, support, teachings and

wonderful insights. To my family, for their understanding and support in my having

chosen this new path in life.

To all non-human animals, for being who you are and living the day by day in the

best way possible nonetheless the obstacles us humans place in front of you. To all

orphaned non-human animals for allowing yourselves to forgive that which I would

have never forgiven.

To my non-human friends Banane, Bianieffe, Clandestine, Derek, Gina, Gloria

(R.I.P.), Josephine, Kay (R.I.P.), Kitóko, Lía, Lisa (R.I.P.), Mvounda (R.I.P.), Pearl,

Pépère, Pizzy (R.I.P.), Scarlett, Yoko and Yombé, for having opened their hearts to

me and allowed me to know them truly and profoundly. For all their unconditional

love and support during the toughest times, and for having been a central driving

force in my life. For all of you who did not survive, I promise to dedicate the rest of

my life to aid, save, respect and love your kind. You are the reasons I am here!


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Table of contents ___________________________________________________________________ Title page Abstract …………………………………………………………………………...…… i Acknowledgements …………………………………………………………………... ii Table of contents ……………………………………………………………………... iii List of tables …………………………………………………………………………… v List of figures ………………………………………………………………………….. vi List of abbreviations ………………………………………………………………….. vii Chapter 1. Introduction ……………………………………………………………….

1

1.1 Overview …………………………………………………………………….. 1 1.2 Chimpanzee distribution and conservation status ……………………… 2 1.3 Release ……………………………………………………………………… 3 1.4 H.E.L.P. Congo …………………………………………………………….. 5 1.5 Relationships and the individual ………………………………………….. 7 1.6 Chimpanzee play behaviour ………………………………………………. 8 1.7 Study aims and research questions ……………………………………… 10 Chapter 2. Materials and methods ………………………………………………….

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2.1 Study site ……………………………………………………………………. 12 2.2 Study group …………………………………………………………………. 13 2.3 Data collection ……………………………………………………………… 13 2.4 Operational definitions and classifications ………………………………. 16 2.4.1 Play ethograms …………………………………………………….. 16 2.4.2 Activity budgets …………………………………………………….. 17 2.5 Statistical analysis ………………………………………………………….. 18 2.6 Ethics and health …………………………………………………………… 19 Chapter 3. Results …………………………………………………………………….

20

3.1 Do the orphans present special-typical chimpanzee play behaviour? .. 20 3.1.1 Lone play session (LP) frequencies and durations ……………...... 20 3.1.2 Successful dyadic social play (sDSP) and para-play (PP) session frequencies and durations …………………………………………… 21 3.1.3 Lone play categories …………………………………………………. 23 3.1.4 Preferred partner in dyadic social play ……………………………... 24 3.1.5 Initiation categories in DSP ………………………………………….. 25 3.1.6 Successful dyadic social play forms ………………………………… 26 3.1.7 Polyadic social play (PSP) sessions ………………………………... 27 3.2 Relationships ……………………………………………………………….. 28 3.2.1 Preferred partner ……………………………………………………… 28 3.2.2 Successful dyads and individual dyad preferences ……………….. 30 3.2.3 Proximity ……………………………………………………………….. 32 Chapter 4. Discussion ………………………………………………………………...

40

4.1 Do the orphans present species-typical chimpanzee play behaviour? . 40 4.1.1 Play frequencies and durations ……………………………………… 40 4.1.2 Partner preferences in dyadic social play ………………………….. 42 4.1.3 Dyadic social play forms ……………………………………………… 44


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4.1.4 Success and aggression in play …………………………………….. 45 4.1.5 Dyadic social play initiation categories ……………………………... 45 4.1.6 Lone play categories …………………………………………………. 46 4.2 Do the orphaned chimpanzees present stable relationships and bonds? ……………………………………………………………………….

48

4.2.1 Bianieffe and Clandestine ……………………………………………. 49 4.2.2 Clandestine and Mila …………………………………………………. 50 4.2.3 Dolly and Pattex ………………………………………………………. 51 4.2.4 Dolly and Clandestine ………………………………………………… 51 4.2.5 Clandestine and Pattex ………………………………………………. 52 4.2.6 Pattex and Youbi ……………………………………………………… 53 4.2.7 Pattex and Mila ………………………………………………………... 54 4.2.8 Youbi and Mila ………………………………………………………… 54 4.3 Individual behaviours – Dolly ……………………………………………... 55 Chapter 5. Conclusions and recommendations ……………………………………

58

5.1 Species-typical play behaviour …………………………………………… 58 5.2 Relationships ……………………………………………………………….. 58 5.3 Individuals …………………………………………………………………… 59 5.4 Evaluation of methods …………………………………………………….. 59 5.5 Future research …………………………………………………………….. 60 References …………………………………………………………………………….

62

Appendices …………………………………………………………………………….

77

Appendix i. Play ethograms …………………………………………………… 77 Appendix ii. Unsuccessful initiation forms (para-play) ……………………… 80 Appendix iii. Negative endings in dyadic social play ……………………….. 82 Appendix iv. Lone play forms …………………………………………………. 83 Appendix v. Initiation forms ……………………………………………………. 88 Appendix vi. Number of DSP bout forms within a session …………………. 90 Appendix vii. Play forms in triadic social play ……………………………….. 91 Appendix viii. Triadic social play interactions ………………………………... 92 Appendix ix. Object use in wild chimpanzees ……………………………….. 93 Appendix x. Object use for non-play activities by the orphaned chimpanzees ……………………………………………………... 94 Appendix xi. Object use in dyadic social play session by the orphaned chimpanzees ……………………………………………………... 96 Appendix xii. Activity budgets …………………………………………………. 97


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List of tables ___________________________________________________________________

Table 1. Study individuals ………………………………………………………… 13

Table 2. Activity budgets ethogram ……………………………………………… 18

Table 3. Frequencies (total) and durations (seconds) for LP sessions by

individual …………………………………………………………………. 21

Table 4. Successful DSP by dyad ……………………………………………….. 31

Table 5. Proportional proximity index values for each individual with other

group members ………………………………………………………….. 33

Table 6. Dyadic social play initiation categories ethogram ……………………. 77

Table 7. Third party intervention forms ethogram ……………………………… 77

Table 8. Lone play categories ethogram ………………………………………... 78

Table 9. Social play forms ethogram …………………………………………….. 78

Table 10. Activity budgets overall and per age-class ………………………..… 98

Table 11. ‘Active’ activity budgets overall and per age-class …………………. 98

Table 12. Activity budgets by individual ……………………………………….… 100

Table 13. ‘Active’ activity budgets by individual ………………………………… 100


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List of figures ___________________________________________________________________ Figure 1. Map of Conkouati Douali National Park ………………………………… 12

Figure 2. Map of the ‘Triangle’ ………………………………………………………. 12

Figure 3. Lone play session frequencies (total) and durations (seconds) by

age-class …………………………………………………………………… 20

Figure 4. Frequencies of sDSP (total), PP sessions (total), and durations

(seconds) for sDSP sessions by age-class …………………………….. 22

Figure 5. Successful dyadic social play by individual …………………………….. 23

Figure 6. Mean percentages for LP categories …………………………………… 24

Figure 7. Mean percentages for DSP initiation categories in total and by

age-class …………………………………………………………………… 26

Figure 8. Top sDSP bout forms within sessions ………………………………….. 27

Figure 9. Third-party intervention forms ……………………………………………. 28

Figure 10. Sociogram for preferred partner invitations in DSP ………………….. 30

Figure 11. Sociogram for Bianieffe’s proximity indexes to peers during different

activities ………………………………………………………………….. 34

Figure 12. Sociogram for Clandestine’s proximity indexes to peers during

different activities ………………………………………………………... 35

Figure 13. Sociogram for Dolly’s proximity indexes to peers during different

activities ………………………………………………………………….. 36

Figure 14. Sociogram for Pattex’s proximity indexes to peers during different

activities ………………………………………………………………….. 37

Figure 15. Sociogram for Youbi’s proximity indexes to peers during different

activities ………………………………………………………………….. 38

Figure 16. Sociogram for Mila’s proximity indexes to peers during different

activities ………………………………………………………………….. 39


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List of abbreviations ___________________________________________________________________

A Adolescent B Bianieffe C Clandestine D Dolly DSP Dyadic play session H.E.L.P. Habitat Ecologique et Liberté des Primates I Infant IUCN International Union for Conservation of Nature J Juvenile LP Lone play M Mila NHPI Natal habitat preference induction NP National Park P Pattex PASA Pan African Sanctuary Alliance PC Proportional count PF Proportional frequency PI Proximity index PP Para-play pPI Proportional proximity index sDSP Successful dyadic play session SP Social play SSC Species Survival Commission TSP Triadic play session UAE United Arab Emirates UK United Kingdom USA United States of America Y Youbi χ2 Chi square U Mann-Whitney U df Degrees of freedom H Kruskal-Wallis


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Chapter 1. Introduction ___________________________________________________________________ 1.1 Overview

Release has become an increasingly popular way of conserving wildlife, with its main

goal to re-establish populations of self-sustained species into the wild while

maintaining their viability (IUCN/SSC Re-introduction Specialist Group 2002).

Nonetheless, releasing primates, and great apes in particular, has been and still is a

great challenge. Chimpanzees, as well as other great apes, attain sexual maturity

late in life and have long inter-birth intervals (Goodall 1986), thus post-release

population growth is slow (Beck et al. 2007). They live in complex social

communities where learning the many motor, cognitive and social skills occurs over

a very long period of time (van Lawick-Goodall 1968; Goodall 1986; Joffe 1997).

Sutherland (1998) maintained that animal behaviour studies are necessary in

preparing animals for release, and that the lack of such studies is one of the main

reasons release initiatives fail. It is possible that the difficulties of great ape releases

are due to the lack of identification and publishing of studies and specific behavioural

protocols for pre-release procedures and evaluations, and to the lack of pre-release

training of certain behaviours essential for survival in the wild. Successful models for

primate reintroductions have yet a long way to go in terms of refinement, and need

fieldwork evaluations and data gathering in order to assess success and viability.

More attention should be paid to the skills chimpanzees need to acquire during

different developmental stages. This way, pre-release monitoring programs can play

an important role in preparing them for final release. In the long run, pre-release

monitoring results and predictions can be compared to post-release results and

survivorship, and thus used as a basis for understanding which release participants

are more likely to survive and reproduce after release, and under what conditions.

The pre-release period is critical not only for identifying prospects for release, but

more so for evaluating relationships between the chimpanzees. It is also important

for identifying behavioural problems in order to ameliorate these, especially if the


2

chimpanzees are still in their developmental stages of life (e.g. infants, juveniles and

adolescents). In these stages, such issues are more likely to be successfully

corrected as younger individuals have a greater degree of behavioural flexibility.

Chimpanzees experience extended infant and juvenile periods, during which they

must acquire the social, motor and cognitive skills they need in order to survive as

adults (van Lawick-Goodall 1968, 1973; Poirier and Smith 1974; Fagen 1993; Watts

and Pusey 1993). During these stages, play is their preferred social activity, and aids

them in practicing and developing these skills (Smith 1982; Špinka et al. 2001).

There are many ways to study developmental and social behaviours. In order for

these to be fully understood, standard analytical methods may not be sufficient. This

study aimed to: document the development of pre-released orphaned chimpanzees

Pan troglodytes troglodytes through the presence of species-typical chimpanzee play

behaviours; analyze current relationships through play, proximity distances and

qualitative data, in order to gather pre-release data that may be helpful in explaining

results post-release; and identify behavioural problems that need to be modified.

1.2 Chimpanzee distribution and conservation status

Chimpanzees Pan troglodytes inhabit savannas, woodlands and a variety of forest

types (Nishida 1968; Boesch and Boesch 1989; Moscovice et al. 2007) across 22

countries of Equatorial Africa, although they may be extinct in Rwanda and Togo,

and are already extinct in Benin and Gambia (Butynski 2001; Kormos et al. 2003;

Oates et al. 2009). There are currently four recognized subspecies of chimpanzees:

the Eastern chimpanzee Pan troglodytes schweinfurthii, the Central chimpanzee Pan

troglodytes troglodytes, the West African chimpanzee Pan troglodytes verus, and the

Nigeria-Cameroon chimpanzee Pan troglodytes vellerosus (Oates et al. 2009).

Since 1996, chimpanzees have been classified as Endangered by the IUCN Red List

of Threatened Species, with their population trend decreasing (Oates et al. 2009).

The major threats to chimpanzee populations are high levels of exploitation,

degradation, and loss of habitat (Cowlishaw 1999; Oates et al. 2009). Their habitat

is being destroyed due to logging, mineral mining, and to slash and burn agriculture


3

(Ogawa et al. 2006; McLennan 2008). Logging alters the habitat and availability of

food sources, fragments populations and therefore disrupts social groups (Morgan

and Sanz 2007). It also allows humans easy access into previously hard to reach

forest areas, and for increased hunting.

Small hunting and poaching have major effects on chimpanzees, since they have

such long developmental stages and slow reproduction rates (Kano and Asato 1994;

Wilkie and Carpenter 1999). It is especially problematic in fragmented habitats

where their population is unlikely to be able to stabilize. Chimpanzees are hunted for

meat, the pet trade, medicinal purpose and crop protection (Brown-Jones and

Pendry 1999; Fa et al. 2002, 2003; Ogawa et al. 2006). They are also caught by

snares that are left in the forest for catching chimpanzees or other wildlife (Waller

and Reynolds 2001; Quiatt et al. 2002). Hunting is an important component of

households, mainly for subsistence (Butynski 2001). With the increase of human

populations, and migration and resettlement due to logging, the opening of roads to

previously inaccessible forest areas, and the ease of transport offered by logging

trucks, hunting has transformed into a commercial enterprise (Kano and Asato 1994;

Wilkie and Carpenter 1999; Walsh et al. 2003; Tutin et al. 2005; Campbell et al.

2008).

Ebola is responsible for drastic decline in chimpanzee densities in Central Africa

(Formenty et al. 1999; Huijbregts et al. 2003; Leroy et al. 2004; Walsh et al. 2007),

while anthrax has also proved to cause many deaths (Leendertz et al. 2006). Many

bacterial, viral and parasitic diseases endanger chimpanzees that contract them from

tourists, researchers, local villagers and their domestic animals and livestock

(Hanamura et al. 2006, 2008; Goldberg et al. 2007; Kaur et al. 2008; Köendgen et al.

2008; Bakuza and Nkwengulila 2009).

1.3 Release

The decline and near extinction of many wild primate species in their natural habitat,

coupled with the increased number of primates arriving at sanctuaries and rescue

centres, has resulted in the increasing lack of space and funds for orphans (Teleki

2001; Farmer 2002; Schoene and Brend 2002; Mills et al. 2005). As a result, the last


4

decades have seen the development of reintroduction guidelines (IUCN/SSC Re-

introduction Specialist Group 2002; Beck et al. 2007) and new procedures for

reintroduction into the wild have been taking place (IUCN/SSC Re-introduction

Specialist Group 2002; Soorae and Baker 2002). Release is a controversial subject.

While the IUCN justifies the need of release of great apes due to their alarming

decline (Beck et al. 2007), some conservationists believe it is expensive, rarely

successful (Soave 1982; Kleiman 1989) and that the money could be better used for

other conservation purposes (Britt et al. 2003).

Published examples of chimpanzee releases include: the nutritional analysis of the

diets of island released chimpanzees in Gabon (Hladik, 1973, 1977); procedures for

chimpanzees transferred from a Liberian laboratory into islands (Hannah and

McGrew 1991), which could not be followed-up due to their aggressive behaviour;

failed attempts to reintroduce orphaned chimpanzees into their natural habitat in

Senegal due to attacks by wild chimpanzees (Brewer 1978); and the release of

chimpanzees into Rubondo Island, Tanzania, in the 1960s, who survived and

reproduced (Borner 1985; Moscovice and Huffman 2001). Although a few

chimpanzee releases have had some degree of success, most were released into

islands, and many remained dependant on humans for food (Farmer et al. 2006).

In 2006 the Pan African Sanctuary Alliance (PASA) held its first African Primate

Reintroduction Workshop (Carlsen et al. 2006), where the Chimpanzee/Bonobo

Working Group placed the “need for standard and accepted pre-release evaluation

of individual suitability for release, as well as an identification of protocols for

released candidates” (pp. 27) as a high priority issue. The proposed solution was to

develop pre-release goals, training for release procedures, and criteria for

determining readiness for release. Although many primate post-release evaluations

conclude that reduced or lack of success were due to deficits in the pre-release

training and evaluation phases, very few studies are published in this regards.

The acquisition and training for predator avoidance, being able to feed/forage, health

protocols, fear and avoidance of humans, interaction with and movement in the

environment, and coping with seasonal environmental changes, are frequently

recurring themes in primate release projects (Kleiman 1989; Griffin et al. 2000;


5

IUCN/SSC Re-introduction Specialist Group 2002; chimpanzees Pan troglodytes:

Tutin et al. 2001; gibbons Hylobates muelleri: Bennet 1992; gorillas Gorilla gorilla

gorilla: King et al. 2006; mandrills Mandrillus sphinx: Peignot et al. 2008; orangutans

Pongo sp.: Grundmann et al. 2000; ruffed lemur Varecia variegata variegata: Britt

and Lambana 2003; Britt et al. 2004, 2008; squirrel monkeys Saimiri sciureus: Vogel

et al. 2002). However, practical pre-release / post-release comparisons or training

are either non-existent or very limited (Custance et al. 2002).

Russon (2002) studied a group of released orangutans in Borneo, focusing on their

foraging problems and solutions. Orangutans may need years in order to develop

food-processing expertise. She concluded that the lack of success in acquiring such

processes is possibly due to poor pre-release training and unreasonable

expectations. These were mainly due to not giving adequate importance to

developmental areas that depend on social learning and take a long time to acquire.

In evaluating the release of ruffed lemurs, Britt et al. (2004) concluded that the

behavioural competence of individuals should be assessed in terms of socialization,

sexual, abnormal and stereotypical behaviours, as well as tameness and the

development of motor skills.

Beck et al. (2007) stress the need of behavioural assessment and monitoring pre-

and post-release. Each individual’s history and behavioural repertoire should be

carefully assessed, including cognition, social interactions and temperament. I have

not found published studies in which readiness for release, relationships and

individual qualities were evaluated pre-release, and then measured post-release in

order to find trends for success and survivorship. Kleiman (1989) also stressed the

importance of acquiring proper social behaviours in order to be able to interact

appropriately with co-specifics. Sadly, studies on social learning generally do not

provide much relevant information for release training programs, as mainly their

focus is on mechanisms rather than function (Custance et al. 2002).

1.4 H.E.L.P. Congo

Since 1996 Habitat Ecologique et Liberté des Primates (H.E.L.P.) has been

successfully releasing endangered chimpanzees P. t. troglodytes (Tutin et al. 2008)


6

into an area within the Conkouati Douali NP in the Republic of Congo, where existing

wild populations of chimpanzees occur. Several scientific articles have been

published on H.E.L.P.’s success covering pre-release, release and post-release

stages. Pre-release studies include a detailed framework of the pre-release and

release procedures (Tutin et al. 2001) including the decision making process,

species- and site-specific considerations, health protocols (Goossens et al. 2001),

conservation implications, and genetic analyses (Goossens et al. 2002). Post-

release studies have been published on the reproduction of released females

(Goossens et al. 2003, 2005), coprophagy (Krief et al. 2004), overall survival and

interactions results (Goossens et al. 2005), diet and activity budgets (Farmer et al.

2006), and on the fission-fusion social organization of the released chimpanzees (Le

Hellaye et al. 2009).

Although H.E.L.P.’s project has been considered a success, a large number of

released individuals died shortly or a few years after release: out of the 37

individuals that were released over a period of 10 years, 54% are known to have

survived, while 24% have died and 22% have disappeared and are presumed dead

(Aliette Jamart, personal communication). The question remains as to why some

individuals survive while others do not. This may have been answered if more in-

depth behavioural and social monitoring would have been performed during the pre-

release stage, but during H.E.L.P.’s earlier chimpanzee releases the staff was

unable to monitor behaviour of the pre-released chimpanzees. It was impossible to

go inside the pre-release islands due to the presence of adults, who posed danger of

attack on human observers (Farmer et al. 2006).

As also observed during gibbon releases (Cheyne and Brulé 2008), H.E.L.P. realized

that chimpanzees were most vulnerable following release. The stress caused by the

release procedure coupled with the unknown new habitat caused some individuals to

flee (Farmer and Jamart 2002; Mills et al. 2005). One of the difficulties faced by

release practitioners is to encourage the animals to settle in an appropriate habitat.

Most released individuals reject the release site and travel fast and long to search for

a suitable ‘home’. This phenomenon is called ‘natal habitat preference induction’

(NHPI). It proposes that this occurs because the newly released individuals want to


7

settle in a place that looks like what they have known as ‘home’, a familiar habitat

they are used to and contains familiar cues (Stamps and Swaisgood 2007).

Recently H.E.L.P. has developed a new method of release whereby the new

candidates are being cared for and followed in the forest, the same place where they

will be released. This allows for intensive behavioural monitoring.

1.5 Relationships and the individual

Chimpanzees live in fission-fusion societies of 19 to 150 individuals. The main group

separates into temporary subgroups of 1 to 30 individuals and varied composition for

a few hours up to a few days at a time (Nishida 1968; Sugiyama 1968, 1984; van

Lawick-Goodall 1968; Sugiyama and Korman 1979; Goodall 1983; Tutin et al. 1983;

Hiraiwa-Hasegawa et al. 1984; Nishida et al. 2003; Mitani 2006).

Although chimpanzee communities have been described as male-bonded societies

in which males form strong alliances and relationships and remain in their natal

group while females disperse (Nishida 1968; Pusey 1979; Goodall 1983), males

have also been observed to disperse (Nishida et al. 1985), and females have been

observed to remain in their natal group (van Lawick-Goodall 1973; Goodall 1983;

HIraiwa-Hasegawa et al. 1984; Nishida and Hiraiwa-Hasegawa 1987). Most studies

have concentrated on male bonding relationships, with the belief that females spend

most time on their own or with their infants. Nonetheless, strong and long lasting

associations between females have been observed both in captivity and in the wild,

with several being the strongest associations within their respective community

(Sugiyama and Korman 1979; de Waal 1989; Lehmann and Boesch 2008). For more

bonding types among females in the wild refer to Nishida 1968; Sugiyama 1968;

Goodall 1983; Tutin et al. 1983; Nishida and Hiraiwa-Hasegawa 1987.

Secure positive relationships are important for both human and nonhuman primates.

Kummer (1978) suggested that these should be viewed from the point of view of the

individual. An individual must evaluate the personality, availability, qualities and

tendencies of each group member. The individual may then choose to try to modify

other individuals’ traits and behaviours by submission, aggression, affiliation or


8

avoidance. Therefore, interactions between two individuals are investments in a

bond that is beneficial to the individual in the present, and may even be so in the

long-term. These relationships may have social, psychological, emotional and/or

ecological values (Kummer 1978; Goodall 1986). Individual lives matter because

they are the building blocks of society (Poole and Granli 2010), beginning with

dyadic relationships.

In the wild, the first and closest bond a chimpanzee infant has is to its mother, which

is reinforced through grooming and play (van Lawick-Goodall 1967). As it becomes

older, it associates with more individuals, but close association with the mother

remains late into adolescent years, and lasts into adulthood. During their juvenile

period, primates learn how to form beneficial associations, frequently doing so

through play (Poirier and Smith 1974; Bekoff 1984; Fairbanks 1993; Palagi et al.

2007). The chimpanzees in this study were orphaned at a developmentally critical

age. Although keepers/observers offer protection and support when needed, most of

the time they only possess each other for support, protection, learning and

companionship. At a certain point the adolescents in the group may join wild

chimpanzee communities. The relationships they build now may provide them with

the emotional, complementary skills and physical support they may need in the near

future. Joining an established wild chimpanzee community may prove difficult to the

orphans. It has been observed that resident females would more frequently aggress

newly arrived females and that aggression is much more frequent between

nulliparous females (Nishida 1989). Thus, strong relationships among the orphans is

of great importance.

1.6 Chimpanzee play behaviour

Play has been observed in many mammalian species, as well as in several reptile

and bird species (Fagen 1981; Bekoff and Byers 1998). Several hypotheses on its

functions have been proposed, with certain disagreement. It seems the functions of

play vary across species, and also vary with age and sex of the individuals (Altmann

1962; Loizos 1967; Lancaster 1971; Poirier and Smith 1974; Dolhinow and Bishop

1976; Fagen 1981, 1993; Smith 1982; Martin and Caro 1985; Fairbanks 1993).


9

Chimpanzee infants must observe, imitate and practice behaviours in order to learn

the appropriate way of performing, and the situations in which to use those

behaviours (Goodall 1986). Their long developmental period aids in acquiring

needed behaviours and skills, and play behaviour plays an important role in

practicing, perfecting and acquiring many of those skills in a relatively safe manner

(van Lawick-Goodall 1968, 1973; Poirier and Smith 1974; Fagen 1993; Watts and

Pusey 1993).

“Play is the hallmark of childhood” (Goodall 1986, pp. 369), and young chimpanzees’

favourite social activity (van Lawick-Goodall 1968). Mothers initiate play with their

offspring when the infant is 1 to 3 months old (van Lawick-Goodall 1967). As months

go by and the mother allows her infant contact with other chimpanzees, its circle of

playmates grows, as well as the amount of play behaviour. This steadily increases

until its peak in its late infant / early juvenile years, even persisting through adulthood

(van Lawick-Goodall 1968; Goodall 1986; Pusey 1990; Markus and Croft 1995;

Spijkerman et al. 1995).

Play behaviour is important in the practice and development of motor, cognitive and

social skills in infant and juvenile primates, all needed to be perfected for adult

survival, as well as in preparation for unexpected situations (Smith 1982; Špinka et

al. 2001). It can aid in becoming familiar with the environment and movement on

and off the ground, for example, in learning which branches are safe and which are

not during locomotion (chimpanzees: van Lawick-Goodall 1968); and in predator

avoidance (rhesus monkeys Macaca mulatta: Symons 1978).

Chimpanzees perfect their nest-building skills through play (van Lawick-Goodall

1973). Primates that use tools may practice and perfect those skills through play

(Smith 1982). Van Lawick-Goodall (1973) observed infant chimpanzees playing with

grass stems while their mothers were termite fishing, and young chimpanzees using

stones and sticks as weapons while playing with young baboons (Goodall 1986).

Chimpanzees may also use objects as tools while playing on their own and with

others (Goodall 1986). Female primates are also able to practice and perfect their

mothering skills, both motor and its role, through play (vervet monkeys

Cercopithecus aethiops: Lancaster 1971).


10

Social animals must be able to relate to others and communicate appropriately.

They must also understand and properly react to different situations within the

context of their species’ and community’s culture, and their own rank within the

community. In its social context, play performs both immediate and belated

functions. Its immediate goals are conflict management and resolution and the

limiting of aggression during stressful situations (Poirier and Smith 1974; bonobos

Pan paniscus: Enomoto 1990, Palagi et al. 2006; chimpanzees: Goodall 1986,

Palagi et al. 2004). Play’s long-term social benefits are various: it helps form

friendships and alliances that may continue through adulthood (Poirier and Smith

1974; Goodall 1986); it aids in teaching proper social communication skills and their

timing in various situations (Poirier and Smith 1974; squirrel monkey Saimiri sp.:

Baldwin and Baldwin 1974); it aids in learning to restrain during certain behaviours

(Poirier and Smith 1974) and in practicing and perfecting fighting skills

(chimpanzees: Goodall 1986; rhesus monkeys: Symons 1978); play also aids in

finding ones place in the social hierarchy by learning the strengths and weaknesses

of peers and oneself, as well as by demonstrating ones abilities and strengths

(chimpanzees: Paquette 1994; howler monkeys Alouatta sp.: Carpenter 1934).

Being the most common social behaviour among pre-adult chimpanzees, play allows

for thorough analysis of normality in development, group cohesiveness, relationships

and individual personalities.

1.7 Study aims and research questions

The principal aims of the project were to: 1) analyze the development of the

orphaned chimpanzees through the presence of species-typical chimpanzee play

behaviours related to motor, object and social skills acquisitions; 2) analyze current

relationships through play behaviours and proximity levels during different activities;

3) identify individual behavioural problems, and; 4) gather pre-release data that may

be helpful in explaining post-release results. The study focused on three main

questions:


11

Q1: Do the orphans present species-typical chimpanzee play behaviour? This was

evaluated by analyzing:

o Lone and social play session frequencies and durations.

o Partner preferences in dyadic social play.

o Dyadic social play forms.

o Success and aggression in play.

o Dyadic initiation categories.

o Lone play categories.

Q2: Does the group of orphaned chimpanzees present stable relationships and

bonds among its members? This was evaluated by analyzing:

o Frequencies and durations of social play sessions.

o Frequency of invitations.

o Success rate in dyadic social play.

o Proximity indexes during different activities.

Q2: Are behavioural problems affecting any of the individuals? This was evaluated

by analyzing:

o Frequencies and durations of lone and social play sessions.

o Frequency of invitations.

o Success rate in dyadic social play.

o Proximity indexes during different activities.

o Percentage of different activity budgets.

o Presence of stereotypical behaviours.


12

Chapter 2. Materials and methods ___________________________________________________________________ 2.1 Study site

Conkouati-Douli National Park (CDNP) is located about 150km Northwest of Pointe

Noire, Republic of Congo, on the border with Gabon (Figure 1). It covers 5,045km2

and consists of a mosaic of savannas, swamp, mangroves, dense, and seasonally or

permanently flooded forests (Hecketsweiler and Mokoko Ikonga 1991; Doumenge

1992; Directorate-General of Environment 2005). The released chimpanzees are

located at the ‘Triangle’ (Figure 2), a 20km2 area within the CDNP, bounded by the

Conkouati lagoon and the Ngongo and Louvandzi rivers (Goossens et al. 2005).

The Triangle is comprised of primary, swamp and inundated forest (Tutin et al.

2001). The ‘Bivouac’ is an area that has been allocated within the ‘Triangle’ for

raising and preparing the group of pre-released chimpanzees. It is located at the

Southwest of the Triangle. Fauna is abundant, with daily sightings and vocalizations

of bush-babies, mangabeys, wild chimpanzees, mandrills, and of a variety of reptiles

and birds (Halit Khoshen, personal observation).

Figure 1. Map of Conkouati Douali NP Figure 2. Map of the ‘Triangle’ (Source http://www.help-primates.org) (Source http://www.help-primates.org)


13

2.2 Study group The study group is composed of six female chimpanzees ranging between the ages

of 3 and 9 years. All were orphaned during infancy and arrived at different

developmental stages and times at H.E.L.P. (Table 1).

Table 1. Study individuals. Year of arrival and approximate age during the study period.

Individuals Approximate age (in years)

Age-class

Year of arrival at H.E.L.P.

Bianieffe (B) 9 Adolescent 2004 Candestine (C) 8 Adolescent 2004 Dolly (D) 6 to 7 Juvenile 2007 Pattex (P) 5 to 6 Juvenile 2006 Youbi (Y) 4 to 5 Infant 2007 Mila (M) 3 to 4 Infant 2007

Age classification follows that of Goodall (1983, 1986), Hiraiwa-Hasegawa et al.

(1984) and Hayaki (1988), and is based on key developmental stages for females:

o Infant (I): 0 to 4 years of age. From birth until the individual eats mostly solid

foods and does not mainly depend on mother during movement.

o Juvenile (J): 5 to 6 years of age. The individual still closely associates with

mother but is no longer dependant on her for milk, transport or night nest

preparation.

o Early adolescent (A): 7 to 10 years of age. The individual is still close to

mother. Irregular swelling of sex skin can be observed.

2.3 Data collection

Data were collected between May 10th and July 22nd 2010. The first three days

were set aside for pilot observations, practice and for letting the chimpanzees

habituate to the observer. Observations were made 7 days a week, for 7 to 8 hours

each day. In order to cover all waking hours (from leaving the night-nest until building

and settling in a new night-nest), the chimpanzees were observed each day in one of


14

two schedules: 7:00 to 14:00, or 10:00 to 18:00. Observations were counterbalanced

between times of day for focal animals.

Four methods were used to collect data: continuous focal, continuous behavioural,

instantaneous scan and ad libitum samplings (Altmann 1974; Martin and Bateson

1993).

Session durations and detailed frequencies of play categories, sub-categories,

forms, initiation and termination forms were recorded for 7 weeks, using focal

continuous sampling with 45-minute sessions followed by 15-minute interval breaks.

The following data were recorded (see operational definitions in page 16 for

ethograms):

o Focal individual’s name.

o Date, start and end time of observation session.

o Lone (LP), social (SP), no-play and para-play (PP) bout and session

frequencies and durations.

o LP and SP categories, sub-categories and forms.

o Initiation and termination categories and forms.

o Initiator and partner(s) name(s).

o Third party intervention and forms.

One of the problems that arose was that at times the individual being observed

remained ‘out of sight’ for an unspecified period of time. When that occurred, ‘time

out’ was noted and data collection was paused. It was also noted if individuals

remained overly close to the observer, due to the possibility of one of them snatching

the recording device or biting when not achieving that goal. When ‘time out’ was

noted, its durations were subtracted from the total observation time for the individual,

and taken into account in order to allow for an equivalent amount of hours of in-sight

observations for all individuals. This was performed by including more observation

hours for individuals whose ‘time out’ resulted in fewer hours than the rest. Total

number of full hours recorded per chimpanzee after subtracting all ‘time out’ was

between 16 and 18.


15

Certain individuals frequently remained ‘out of sight’ during play, which would not

permit analyzing true frequencies of LP and SP between age-classes and

individuals. For such purposes, frequencies of LP and SP were collected for 4 weeks

using continuous behavioural sampling with 45-minute sessions followed by 15-

minute interval breaks. In order to record true frequencies, data were recorded only

when all group members were visible.

Simultaneously, 15-minute instantaneous scan samples were performed in order to

record distances between individuals during different activities, and activity budgets.

Each scan was performed on all individuals at the same time, resulting in 11,358

scans for different dyad combinations, ranging from 373 to 385 scans per dyad

where both dyads were visible. Scans where it was not possible to measure

proximity between one individual and all of its peers were discarded in order to avoid

biasing the results.

Distances between dyads were measured by counting the times when an individual

was at a distance of less than 1 meter (<1), 1 to 5 meters (1-5), 5 to 10 meters (5-10)

and more than 10 meters apart (>10) from each other group member. Proximity

indexes were then calculated using the following formula: 1. Proportionate weights

were assigned to each distance (<1=4, 1-5=3, 5-10=2, >10=1); 2. Each weight was

multiplied by the observed count for the distance. 3. The four resulting numbers were

added into what is classed the proximity index (PI).

PI = (counts of <1 X 4)+(counts of 1-5 X 3)+(counts of 5-10 X 2)+(counts of >10 X 1)

There were unequal sample numbers across dyads, therefore proportional proximity

indexes (pPI) were calculated in order to compare activity budgets between age-

classes. These counts were calculated by: 1. Dividing the PI by the total number of

samples for the dyad; 2. Multiplying the resulting number by a constant, the number

of scans for the dyad with highest number of samples.

PI of dyad Y pPI = ----------------------------------------- X number of samples for constant dyad Number of samples for dyad Y


16

As a result, higher PI and pPI numbers account to closer proximity.

Proportional counts (PC) were calculated when evaluating activity budgets between

age-classes and individuals, by using the following formula:

scan count for 1 activity type for Y PC = ------------------------------------------------------ X number of samples for constant Total scans for individual or age-class Y

Ad libitum data were recorded during ‘time out’, session breaks, and when relevant

behaviours were performed by a non focal. These data are used in the discussion to

assist in data interpretation.

Data were collected using a portable audio-recorder combined with a watch to allow

continued visual contact. Each night data were transcribed on paper (due to lack of

electricity in the forest) and later (July 23rd-August 10th) into Microsoft® Word and

Excel 2004 for Mac®.

2.4 Operational definitions and classifications

2.4.1 Play ethograms

‘Play’ was identified as a fragmented sequence of behaviours that may include

repetition, exaggeration, and restrain, that seem to have no immediate purpose, and

may be accompanied by ‘play-face’ and/or ‘play-pant’ (Jolly 1985; Mendoza-

Granados and Sommer 1995).

‘Play-face’ was defined as retraction of the corners of the lips, where the mouth may

be fully or partially open, showing all teeth or only the lower teeth respectively. ‘Play-

pant’, also known as ‘laughing’, is defined as soft panting sounds that may become

jumpy and rough panting sounds, resembling human laughter (van Lawick-Goodall

1968; Plooij 1984).


17

Definitions and interpretations of play, para-play, dyadic and polyadic bouts/sessions

were adapted from Hayaki’s (1985) and Mendoza-Granados and Sommer’s (1995)

research:

o Social play (SP): play behaviour an individual performs with two or more

partners.

o Lone play (LP): play behaviour performed by an individual on its own.

o Play bout: all occurrences of one type of play from the moment play is

initiated, until at least one player stops its activities for 10 seconds to 3

minutes.

o Non-play bout: interruption of a play bout for 10 seconds to 3 minutes.

o Para-play bout (PP): an unsuccessful act of initiating play that does not

terminate in SP among the actors.

o Play session: a series of play and non-play bouts, with intervals of 10 seconds

to 3 minutes between them.

o Dyadic play session (DSP): when only two individuals engage in play or para-

play.

o Polyadic play session: when more than two individuals engage in play or

para-play.

o Triadic play session (TSP): when three individuals engage in play or para-

play.

o Successful dyadic play session (sDSP): when two individuals engage in a

play session.

Ethograms for lone play and dyadic social play initiation categories, social play and

third part intervention forms are located in Appendix i.

2.4.2 Activity budgets Activity budgets were primarily used in order to evaluate proximity distances for

different tasks between individuals, and for evaluating behavioural deficiencies at the

individual level. These were also used for gathering initial data on activity budgets for

the non-adult orphaned chimpanzees (Appendix xii).


18

Activity budgets were separated into two categories: ‘non-active’ and ‘active’. ‘Active’

budgets were further divided into ‘social’ and non-social’ (See Table 2 for ethogram).

Table 2. Activity budgets ethogram

Category Subcategory Form Description Non-active Rest Lay down, sit

Active Social Affiliative Social play, groom, hug Social Non affiliative Tease, aggression Non-social Feed/forage Search and processing of food,

eating and swallowing Non-social Movement Locomotion on or off the ground,

over short or long distances Non-social Other Abnormal or stereotypical

behaviours, exploration, alert in case of danger, lone play

2.5 Statistical analysis

Microsoft® Excel 2004 and IBM® PASW Statistics 18 for Mac® software were used

for running statistical tests and for graphical display of results. Adobe® Photoshop

for Mac® was used for building sociograms.

Non-parametric statistical tests and descriptive statistics were used due to the small

sample size, which did not yield normally distributed data. The level of significance

was set to 5%.

Tests used included:

o Chi square, when comparing: 1) LP, sDSP, and PP frequencies across age-

classes, and between individuals within age-classes; 2) LP categories

between age-classes; 3) partner choice in DSP within age-classes; 4)

initiation forms in DSP between age-classes; 5) frequency of participation in

TSP between individuals; 6) preferred partner by invitation for DSP between

individuals; 7) preferred partner by frequency of total sDSP sessions per

individual; 8) activity budgets within and between age-classes.


19

o Kruskal-Wallis, when looking at durations across age-classes for LP and

successful DSP sessions. Mann-Whitney U when performing post hoc tests

where Kruskal-Wallis demonstrated significance.

o Binomial tests, when analyzing preferred partner in DSP initiations for: 1)

older versus younger initiator; 2) initiation with same age partner versus

different age partner.

o Descriptive statistics for presenting: 1) overall and individual success rate for

DSP; 2) forms of rejecting play invitations; 3) individual frequency of

successful DSP; 4) LP categories for age-classes; 5) preferred initiation form

in DSP within age-classes; 6 overall and within age-class forms of DSP bouts;

7) polyadic social play sessions with four individuals; 8) percent and mean

durations for triadic social play forms overall and between age-classes; 9)

success rate, average duration and mean percentage among and between

dyads; 10) proximity indexes among and between individuals; 11) activity

budgets for individuals; 12) percent of initiation forms within DSP categories.

There was only one possible dyad for adolescent-adolescent (A+A), juvenile-juvenile

(J+J) and infant-infant (I+I) combinations, and 4 possible dyads for adolescent-infant

(A+I), juvenile-infant (J+I) and adolescent-juveniles (A+J) combinations. Therefore,

whilst comparing dyads by the different age-class combinations, proportional

frequencies (PF) were calculated in order to provide each dyad combination the

same weight. This was done by multiplying age-class dyads with one possible

partner by 4, the total number of possible dyads for other age-class combinations.

2.6 Ethics and health

The investigator complied with the Animal Behavior Society’s Guidelines for the

Treatment of Animals in Behavioural Research and Teaching (1997) and the PASA

Handbook 2006-2007 research policies, as well as with the human health guidelines

presented in PASA’s Primate Veterinary Healthcare manual (2004) and H.E.L.P.’s

contract agreement. An ethics proposal was approved by the ethics panel at Oxford

Brookes University’s School of Social Sciences and Law.


20

Chapter 3. Results ___________________________________________________________________ 3.1 Do the orphans present species-typical chimpanzee play behaviour?

3.1.1 Lone play session (LP) frequencies and durations

Frequencies of LP sessions (n=349) significantly decreased with age (χ2=50.275,

df=2, p≤0.001). Post hoc Chi square tests show highly significant differences

between juveniles and adolescents (χ2=13.565, df=1, p≤0.001) and infants and

juveniles (χ2=12.214, df=1, p≤0.001). (See Figure 3).

Although average durations increased with age (Figure 3), overall differences

between age-classes were not significant (H=2.888, df=2, p=0.236).

Figure 3. Lone play session frequencies (total) and average durations (seconds) by age-class. Data for durations include minimum and maximum durations, as well as the total number of observation where complete sessions were recorded.


21

A large difference was found for frequency of LP sessions between individuals of the

same age-class for adolescents and juveniles, but not for infants (see Table 3):

adolescents Bianieffe and Clandestine (χ2=52.563, df=1, p≤0.001); juveniles Dolly

and Pattex (χ2=60.965, df=1, p≤0.001).

Table 3. Frequencies (total) and durations (seconds) for LP sessions by individual. Individuals are listed from oldest to youngest. Duration is presented in mean, maximum and minimum per individual.

Duration (sec) Individual Frequency

Mean Min Max Bianieffe 3 n/a n/a n/a

Clandestine 61 197.07 6 950 Dolly 15 69 15 164 Pattex 98 211.9 6 976 Youbi 83 98.91 6 389 Mila 89 82.15 6 468

3.1.2 Successful dyadic social play (sDSP) and para-play (PP) session

frequencies and durations

Overall success rate for DSP was 80.09% [sDSP (716) / total number of initiations

(894)]. Infants presented the highest rate of success (83.45%), followed by

adolescents (79.82%) and juveniles (74.90%). sDSP frequencies (Figure 4)

significantly decreased with age (χ2=75.966, df=2, p≤0.001). Post hoc Chi square

tests show significant differences between infants and juveniles (χ2=43.756, df=1,

p≤0.001) and infants and adolescents (χ2=58.000, df=1, p≤0.001). No significant

difference was observed when comparing juveniles to adolescents (χ2=1.087, df=1,

p=0.297). PP frequencies (Figure 4) also significantly decreased with age

(χ2=6.079, df=2, p≤0.05). Seventeen different forms of not accepting play invitations

were observed (Appendix ii), the most common being ‘ignore’ (65/93, 69.89%),

followed by ‘leave’ (11/93, 11.83%). Only 6 (4.05%) sDSP sessions ended in a

negative form (Appendix iii).

Mean duration of sDSP sessions (Figure 4) significantly increased with age

(H=6.752, df=2, p≤0.05). Mann-Whitney U post hoc tests revealed significant

differences between infants and adolescents (U=2652.90, df=1, p≤0.05), and


22

juveniles and adolescent (U=1766.50, df=1, p≤0.05). No significance was found

between infants and juveniles (U=4935.00, df=1, p =0.910).

Figure 4. Frequencies of sDSP (total), PP sessions (total), and average durations (seconds) for sDSP sessions by age-class. Data for durations include minimum and maximum durations, as well as the total number of observation where complete sessions were recorded.

Mila participated in more sDSP (25%) and presented the highest successes rate

among all other individuals, while Dolly participated in the least amount of sDSP

(9%) and presented the lowest success rate. See Figure 5 for details.


23

Figure 5. Successful dyadic social play by individual. Individual ratios represent the rate of success of DSP out of the total number of intents (sDSP+PP) made and received by each individual. Total sessions represent the frequency of sDSP an individual participated in.

3.1.3 Lone play categories

There were significant differences in frequencies of LP categories for infants

(χ2=59.761, df=2, p≤0.001), juveniles (χ2=46.231, df=2, p≤0.001) and adolescents

(χ2=49.439, df=3, p≤0.001). The most frequently observed category for infants was

‘locomotor’, followed by ‘object’; for juveniles and adolescents it was ‘object’,

followed by ‘locomotor’ (see Figure 6). An ethogram for all observed forms of play

within LP categories is located in Appendix iv.


24

Figure 6. Mean percentages for LP categories. Mean percentages represent the number of one type of LP category relative to the total number of observations per age-class. Imaginary play was not observed and was thus excluded from the graph.

Significant preferences were observed for ‘object’ play for Clandestine (χ2=47.474,

df=3, p≤0.001) and Pattex (χ2=39.522, df=2, p≤0.001), and for ‘locomotor’ play by

Mila (χ2=38.625, df=2, p≤0.001). No significant preferences were found for either

Dolly (χ2=0.818, df=1, p=0.366) or Youbi (χ2=2.273, df=1, p=0.132).

3.1.4 Preferred partner in dyadic social play

When analyzed by initiations (sDSP+PP), play was significantly initiated by the older

partner (120 vs. 81 sessions; binomial test, p≤0.01), and same-age partners were

significantly more selected as play partners than different-age partners (252 vs. 139;

binomial test, p≤0.001).

When analyzed by age-class dyad in sDSP sessions, frequencies differed

significantly for partner choice for adolescents (χ2=77.669, df=2, p ≤0.001). Post hoc


25

tests revealed that adolescents played more with other adolescents (compared with:

infants, χ2=52.313, df=1, p≤0.001; juveniles χ2=44.900, df=1, p≤0.001). No

significance was found for adolescents over playing with juveniles or infants

(χ2=0.360, df=1, p=0.549).

Frequencies differed significantly for juveniles (χ2=21.924, df=2, p≤0.001). Post hoc

tests revealed that juveniles played significantly more with other juveniles

(χ2=10.450, df=1, p≤0.001) and infants (χ2=22.132, df=1, p≤0.001), compared with

adolescents. No significance was found for juveniles over playing with other juveniles

or infants (χ2=2.333, df=1, p=0.127).

Frequencies also differed significantly for infants (χ2=344.346, df=2, p≤0.001). Post

hoc tests revealed that infants played more with other infants (compared with:

juveniles, χ2=155.928, df=1, p≤0.001; adolescents, χ2=17.114, df=1, p≤0.001).

Infants also played significantly more with juveniles than with adolescents

(χ2=246.949, df=1, p≤0.001).

3.1.5 Initiation categories in DSP

There were significant differences in categories of DSP initiation (n=180, χ2=85.611,

df=4, p≤0.001). As a whole, the most common was ‘locomotion’, closely followed by

‘physical contact’ (Figure 7). The most popular forms of ‘physical contact’ were ‘grab’

(29.03%) and ‘jump on’ (22.58%). The most popular forms of ‘locomotion’ were

‘swing towards, above or next to’ (58.57%) and ‘approach’ (40%). There were

significant differences for initiation categories for infants (χ2=55.636, df=4, p≤0.001)

and juveniles (χ2=41.252, df=4, p≤0.001). No significance was found for adolescents

(χ2=11.394, df=4, p=0.22). An ethogram for all observed forms of initiation is located

in Appendix v.


26

Figure 7. Mean percentages for DSP initiation categories in total and by age-class. Mean percentages represent the number of one type of initiation category relative to the total number of initiations.

3.1.6 Successful dyadic social play forms

Complete details were recorded for 135 sDSP sessions. Up to 10 different play-bout

forms were observed within one sDSP (Appendix vi), with the most predominant

being 2 (25.19%), followed by 1 type (19.26%).

In total, 27 different bout forms were observed (Appendix i: Social play forms),

comprising 498 occurrences within sessions. Figure 8 represents top observed bout

forms. ‘Play-bite’ and ‘wrestle’, both rougher types of play, were frequently observed

only in sDSP between adolescents.


27

Figure 8. Top sDSP bout forms within sessions. Numbers represent mean percentage of each bout form within the age-class dyad. These were rounded up for space reasons.

3.1.7 Polyadic social play (PSP) sessions

There was only 1 observed polyadic play session between 4 individuals

(Mila+Bianieffe+Youbi+Pattex), lasting 33 seconds, and including ‘touch’, ‘grab’ and

‘pull’ bouts.

There were 42 cases in which a third individual tried to join an sDSP session. Figure

9 presents the mean percentage of observed third party interventions. When ‘joining’

and ‘inclusion’ occurred, the result was triadic social play session (TSP).


28

Figure 9. Third-party intervention forms. Frequencies are represented in the inside of the pie chart and mean percentages outside the pie chart.

Complete durations for TSP were recorded for 22 sessions. The mean duration was

110.63 sec (SD=123.33, min=12, max=510, median=58). Only one TSP ended in a

negative manner (Dolly+Bianieffe+Youbi), with one of the players screaming (Youbi).

The most frequent triad was composed of Mila+Youbi+Pattex. Significant differences

were found between the frequencies in which all individuals participated in TSP

(χ2=21.846, df=5, p≤0.001), with Mila (n=21), Pattex (n=20) and Youbi (n=18)

participating in most of the observed TSPs. Infant participation accounted to 51.9%,

juvenile’s to 30.8% and adolescent’s to 16.67% of observations. Play forms are

located in Appendix vii and a description table of TSP interactions in Appendix viii.

3.2 Relationships 3.2.1 Preferred partner

Figure 10 presents preferred partner by invitation for DSP. Significant differences

were found for preferred partners (χ2=29.802, df=5, p≤0.001), with Mila (23.27%),


29

Youbi (22.28%) and Pattex (22.28%) being the most invited, and Dolly (7.43%) the

least invited. In fact, Dolly was never recorded being invited by Bianieffe.

To examine partner preferences, Chi square tests were run on frequencies of DSP

invitations. Tests were not performed for Bianieffe and Clandestine due to small

numbers of observations for some partners (>6), however Bianieffe invited

Clandestine most frequently, while Clandestine did so with Mila. There was no

significant difference in the frequency of invitations by Dolly across the different

potential partners (χ2=8.000, df=4, p=.092), although numbers show she initiated

play more with Pattex. There was a significant difference in the frequency of

invitations by Pattex across different potential partners (χ2=12.222, df=4, p≤0.05),

and she invited Mila and Youbi the most. No significant difference was found

between her choosing Mila over Youbi (χ2=0.037, df=1, p=0.847). Youbi also varied

her invitations (χ2=17.111, df=4, p≤0.01), and invited Mila and Pattex the most. No

significant difference was found in choosing Mila over Pattex (χ2=0.533, df=1,

p=0.465). Mila also significantly differed in giving invitations across individuals

(χ2=38.314, df=4, p≤0.001), inviting Youbi and Pattex the most. No significant

difference was found in choosing one over the other (χ2=1.195, df=1, p=0.274).


30

Figure 10. Sociogram for preferred partner by invitation in DSP. Individuals closer to the centre were invited more frequently by their peers. Arrows represent the direction of the invitation. Numbers represent the frequency of invitations.

3.2.2 Successful dyads and individual dyad preferences

Overall, highest frequency of sDSP occurred between Youbi+Mila, followed by

Pattex+Youbi and Pattex+Mila. All but 1 dyad presented more successful DSP that

PP. The most successful dyads were Bianieffe+Clandestine, Clandestine+Mila and

Youbi+Mila. The least successful were Dolly+Youbi, Dolly+Mila and

Clandestine+Pattex. The longest average DSP duration was held by

Bianieffe+Clandestine. The shortest average duration was between Dolly+Youbi and

Clandestine+Youbi. See details in Table 4.


31

Table 4. Successful DSP by dyad. Success rate represents the total number of sDSP interactions out of total DSP initiations within the dyad. Average duration represents the average duration in seconds observed for successful DSP within the dyad. Mean percentage of DSP relative to other dyads represents the percent total of sDSP out of all observed DSP sessions for all dyads. Dyads are organized by descending rate of success.

Dyads Rate of

success (%)

Average duration

(sec)

Mean percentage of DSP relative to

other dyads

Bianieffe + Clandestine 95 602.43 10 Clandestine + Mila 95 330.88 5 Youbi + MIla 90 205.61 27 Pattex + Mila 86 214.18 12 Pattex + Youbi 84 121.92 13 Clandestine + Youbi 80 52 6 Bianieffe + Dolly 80 284.5 3 Dolly + Pattex 78 144.5 6 Mila + Bianieffe 76 315 4 Clandestine + Dolly 74 91.4 5 Bianieffe + Pattex 62 152.5 2 Youbi + Bianieffe 61 96.55 5 Clandestine + Pattex 53 390.75 3 Dolly + MIla 53 125 2 Dolly + Youbi 50 40.5 2

Significant difference was found for who each individual played the most with

(Bianieffe, χ2=29.954, df=4, p≤0.001; Clandestine, χ2=35.701, df=4, p≤0.001; Dolly,

χ2=10.923, df=4, p=0.05; Pattex, χ2=51.504, df=4, p≤0.001; Youbi, χ2=171.089,

df=4, p≤0.001; Mila, χ2=143.765, df=4, p≤0.001). Therefore, post hoc Chi square

tests were performed in order to analyze individual preferences.

Bianieffe played more with Clandestine over all possible partners (over: Dolly,

χ2=12.755, df=1, p≤0.001; Pattex, χ2=18.689, df=1, p≤0.0001; Youbi, χ2=7.407,

df=1, p≤0.006; Mila, χ2=11.520, df=1, p≤0.001). No significance was found in playing

more between any other possible partner. Clandestine played more with Bianieffe

over all possible partners (over: Pattex, χ2=15.511, df=1, p≤0.001; Youbi,


32

χ2=26.561, df=1, p≤0.001; Mila, χ2=5.786, df=1, p≤0.01; Dolly, χ2=7.407, df=1,

p≤0.01). Dolly played more with Pattex over Youbi (χ2=7, df=1, p≤0.01) and Mila

(χ2=5.828, df=1, P≤0.05), and with Clandestine over Youbi (χ2=4.167, df=1, p≤0.05).

Pattex played more with Youbi and Mila. No significant difference was found

between the two (χ2=0.044, df=1, p=0.833). Mila was significantly more Pattex’s play

partner than Clandestine (χ2=21.407, df=1, p≤0.001), Bianieffe (χ2=24.923, df=1,

p≤0.001) and Dolly (χ2=8.138, df=1, p≤0.01). Youbi was significantly more her play

partner than Bianieffe (χ2=26.741, df=1, p≤0.001), Clandestine (χ2=23.143, df=1,

p≤0.001) and Dolly (χ2=9.328, df=1, p≤0.01). Significance was also found in DSP

with Dolly over Bianieffe (χ2=5.828, df=1, p≤0.05) and Clandestine (χ2=3.903, df=1,

p≤0.05). No significant difference was found for Pattex playing more with

Clandestine over Bianieffe (χ2=0.637, df=1, p=0.637).

Youbi played significantly more with Mila than with any other possible partner (over:

Pattex, χ2=17.028, df=1, P≤0.001; Dolly, χ2=75.922, df=1, p≤0.001; Bianieffe,

χ2=54.321, df=1, p≤0.001; Clandestine, χ2=83.646, df=1, P≤0.001). She also played

significantly more with Pattex than with Clandestine (χ2=35.280, df=1, p≤0.001),

Dolly (χ2=28.698, df=1, p≤0.001) and Bianieffe (χ2=13.349, df=1, p≤0.001). No

significance was found in play frequency with Clandestine over Dolly (χ2=0.818,

df=1, p=0.366), but she did play more with Bianieffe than with Clandestine

(χ2=8.048, df=1, p≤0.01) and Dolly (χ2=4.167, df=1, p≤0.05).

Mila played significantly more with Youbi than with any other possible partner (over:

Pattex, χ2=18.712, df=1, p≤0.001; Dolly, χ2=73.485, df=1, p≤0.001; Clandestine,

χ2=50.667, df=1, p≤0.001; Bianieffe, χ2=62.259, df=1, p≤0.001). She also played

significantly more with Pattex over Bianieffe (χ2=16.860, df=1, p≤0.001), Dolly

(χ2=24.923, df=1, p≤0.001) and Clandestine (χ2=9.921, df=1, p≤0.01).

3.2.3 Proximity

Table 5 shows closest proximity was maintained by Youbi+Mila, followed by

Dolly+Clandestine and Pattex+Youbi. The greater distance was found to be between

Clandestine+Pattex.


33

Table 5. Proportional proximity index values (pPI) for each individual with other group members. Higher values mean closer proximity, while lower values mean greater distance. Bolded purple numbers represent the dyad with closest proximity, and bolded green numbers represent the dyad with greatest distance.

Bianieffe Clandestine Dolly Pattex Youbi Mila

Bianieffe 158.33 157.25 123.68 161.97 161.47 Clandestine 158.33 178.7 118.1 125.9 145.5 Dolly 157.25 178.7 129.94 145.72 155.49 Pattex 123.68 118.1 158.33 170.58 155.88 Youbi 161.97 125.9 145.72 170.58 224.06 Mila 161.47 145.5 155.49 155.88 224.06

Overall, Bianieffe presented closest proximity to Mila and Youbi, and remained the

farthest from Pattex. Clandestine and Dolly presented closest proximity to each other

and least to Pattex. Pattex presented closest proximity to Youbi, and remained the

farthest from Clandestine. Youbi and Mila presented closest proximity to each other

and least to Clandestine. Figures 11 through 16 present proximity indexes for each

individual during different activities.


34

Figure 11. Sociogram for Bianieffe’s proximity indexes to peers during different activities. Individuals closer to the centre were the ones Bianieffe maintained closer proximity to. Numbers represent PIs.


35

Figure 12. Sociogram for Clandestine’s proximity indexes to peers during different activities. Individuals closer to the centre were the ones Clandestine maintained closer proximity to. Numbers represent PIs.


36

Figure 13. Sociogram for Dolly’s proximity indexes to peers during different activities. Individuals closer to the centre were the ones Dolly maintained closer proximity to. Numbers represent PIs.


37

Figure 14. Sociogram for Pattex’s proximity indexes to peers during different activities. Individuals closer to the centre were the ones Pattex maintained closer proximity to. Numbers represent PIs.


38

Figure 15. Sociogram for Youbi’s proximity indexes to peers during different activities. Individuals closer to the centre were the ones Youbi maintained closer proximity to. Numbers represent PIs.


39

Figure 16. Sociogram for Mila’s proximity indexes to peers during different activities. Individuals closer to the centre were the ones Mila maintained closer proximity to. Numbers represent PIs.


40

Chapter 4. Discussion ___________________________________________________________________ 4.1 Do the orphans present species-typical chimpanzee play behaviour?

Locomotor patterns, as well as some components of gestures, posture and vocal

communication of chimpanzees are genetically acquired, but moulding of such

behaviours is greatly helped by adult chimpanzees (van Lawick-Goodall 1973). Wild

chimpanzees learn during their daily interactions and experience with the

environment proper locomotor skills such as climbing trees and grasping branches.

With practice, trial and error experiments, and increased familiarity with the

environment, chimpanzees increase their coordination and skills. They also learn, for

example, how to react appropriately to danger in the environment, proper tool-using

behaviours, food selection and travel roots. These are learned by a combination of

observing, experimenting, and direct teaching by experienced adults, while also

practiced through play (van Lawick-Goodall 1973).

The six orphan chimpanzees in this study did/do not have the privilege of living with

nor learning through their mothers and other adult chimpanzees. Thus, a question

arises to whether their social, cultural and performance skills are developing

properly. Some of these are hereby evaluated through the analysis of play

behaviour.

4.1.1 Play frequencies and durations

Both in lone and social play infants played more than juveniles, and juveniles played

more than adolescents. Similar results, in which play frequencies peaked in infancy

and then declined with age, were found in captive studies where chimpanzees lived

in family groups (Bloomsmith et al. 1994; Markus and Croft 1995; LP: Spijkerman et

al. 1995; SP: Merrick 1977; Savage and Malick 1977; King et al. 1980; Spijkerman et

al. 1995), peer groups (SP: Spijkerman et al 1995), and in wild chimpanzee studies

(SP: van Lawick-Goodall 1968; Clark 1977; Hayaki 1985).


41

Peak frequencies of play during infancy, and decline with age, has also been

reported for other primate species, both in the wild and in captivity (baboons Papio

anubis: Owens 1975; Cheney 1978; capuchins Cebus apella: de Resende et al.

2004; Japanese macaques Macaca fuscata: Koyama 1985; lowland gorillas: Brown

1988; mantled howlers Alouatta palliata: Zucker and Clarke 1992).

Several theories have been proposed to why this occurs. As van Lawick-Goodall

(1973) noted during her wild chimpanzee study, younger chimpanzees are more

flexible in their behaviours, more innovative, exploratory and adventurous. This has

also been observed in other primate studies (chimpanzees: Welker 1956; Japanese

macaques: Itani 1958; Frisch 1968; Nildiri langurs Presbytis johnii: Poirier 1970).

If viewed through costs and benefit proportion, it is easy to understand why younger

animals, who are in their main developmental period of physical and social

development, play more. They have adults to protect them from danger, and do not

have to worry about reproduction and the dominance hierarchy, for example. At the

same time, they need to develop their locomotive and social skills. As Fagen (1981)

suggested, play behaviour can modify and form different developmental aspects.

On the other hand, as animals grow older, the benefits and benefit-costs ratios for

play are lower (Fagen 1981; Caro 1995). Goodall (1986) noted that although adult

females had rarely been seen playing with each other, and adult males did not play

often either, when there was plenty of food and the chimpanzees gathered in large

groups, adult play was more frequent, thus the cost of foraging for food was

overridden. As animals grow older, they become less dependant on their mothers,

and more focused on surviving, foraging, and reproducing, and thus play becomes

less frequent. On the other hand, their locomotor and social skills are already

advanced, if not completely acquired.

Average durations of play were highest for adolescents for both lone and dyadic

social play, and lowest for infants for lone play. Nonetheless, results for LP indicated

differences were not significant across age-classes. Possibly this is due to the small

sample size and the large variability between session durations. These results

coincide with several studies on other primate species (baboons: Owens 1975;


42

mantled howlers: Zucker and Clarke 1992), but contrast with both captive (LP:

Markus and Croft 1995; SP: Savage and Malick 1977; King et al. 1980), wild

chimpanzee (van Lawick-Goodall 1968; Pusey 1990), and some other primate

studies (capuchins: de Resende et al. 2004). Inconsistencies may be due to different

methods employed for data gathering and calculating time spent in play between this

study and the different studies, and because of low number of subjects in this study.

4.1.2 Partner preferences in dyadic social play

Partner preferences were evaluated in different forms. First, initiations, resulting in

both sDSP and PP, were analyzed to see if older individuals initiated play more

frequently than younger individuals, and if same age-class partners were more

frequently selected than different age-class partners. And second, partner

preferences were analyzed by and between age-classes for sDSP sessions.

As also observed in a captive chimpanzee study performed by Mendoza-Granados

and Sommer (1995), and by Symons 1978 in studies of rhesus macaques, older

individuals were the most frequent initiators of DSP. This was also observed by

Owens (1975) in a troop of wild baboons. When initiations were not performed by the

oldest individual, they were performed by the larger individual. Males also initiated

more bouts than females, even when the females were slightly older than

themselves. Owens (1975) explains that this could have happened because males

play more roughly than females, thus females could have been intimidated in

initiating play with them.

In a study performed by Paquette (1994) on a peer group of captive chimpanzees,

most play initiations were performed by the more dominant individual, unless a

subordinate was interested in challenging the dominant rank during unstable

hierarchy times. Goodall (1986) observed that play among different sexed adult

chimpanzees was almost always initiated by the male.

What all these studies have in common is that the strongest/biggest individual was

most often the initiator, which may indeed infer that younger/less strong individuals


43

may be intimidated by the older/stronger individual, and thus hesitate in initiating a

play interaction with the latter.

All age-class individuals played more with partners from their same age-class.

Juveniles played more with infants than adolescents and infants played more with

juveniles over adolescents, while adolescents did not present preference over

playing with infants over juveniles. Identical results for juveniles were found for

captive lowland gorillas (Palagi et al. 2007).

Preference for same age-class partners was observed in other chimpanzee

(captivity: King et al. 1980; Mendoza-Granados and Sommer 1995; wild: Van

Lawick-Goodalll 1968; Pusey 1990) and primate species studies (baboons: Owens

1975; Cheney 1978; colobus monkey Colobus guereza: Oates 1977; lowland

gorillas: Brown 1988; Maestripieri and Ross 2004; rhesus monkeys: Symons 1978;

crab-eating macaques Macaca irus: Fady 1969), both in the wild and in captivity. In a

study performed by Cheney (1978) on baboons, infants of both sexes, and juvenile

and adolescent males, played more with same age-class/sex partners. In contrast,

juvenile and adolescent females played more with infants. In a study performed by

Fairbanks (1993) he noted that vervet monkeys chose play partners of similar

strength and size.

This can probably be explained by the fact that same age-class individuals are closer

in size and strength and may have more in common in preferences of play forms and

in force employed during play, thus may be able to take better advantage of some of

the functions of play, as explained by the motor-training and social-relationship

hypotheses on play (Altmann 1962; Poirier and Smith 1974; Fagen 1981; Fairbanks

1993).

Adolescents may not find playing with infants as challenging, since the latter have

limited physical capabilities. At the same time, for infants to play with older

individuals, mainly with adolescents, could be too challenging (Altmann 1962; Fady

1969; Poirier 1970).


44

When older individuals play with younger ones, for example, they must self-handicap

in order for the session to last longer or even occur (baboons: Owens 1975; Pereira

and Preisser 1998; bonobos: Enomoto 1990; chimpanzees: Loizos 1969; King et al.

1980; Hayaki 1985; Mendoza-Granados and Sommer 1995); thus play likely occurs

strictly for fun, and has no additional functions.

By playing with same age-class partners, individuals may be able to take advantage

of the functions of play: it may aid them in practicing and developing coordination of

fighting skills (Fagen 1981; human children Homo sapiens: Humphreys and Smith

1987; vervet monkey: Fairbanks 1993); in learning and demonstrating their strengths

to and learning the weaknesses of their peers (Poirier and Smith 1974;

chimpanzees: Paquette 1994); and in perfecting their locomotor and muscular

coordination (Fagen 1981; chimpanzees: van Lawick-Goodall 1968; vervet monkeys:

Fairbanks 1993).

4.1.3 Dyadic social play forms

It is normal to observe play movement patterns that are also involved in fights,

escapes and hunts (bird species: Diamond and Bond 2003; chimpanzees: van

Lawick-Goodall 1968; other primate species: Pellis and Pells 1997; spinner dolphins

Stenella longirostris: Silva-Jr et al. 2005). Symons (1978) hypothesised that these

play-fighting bouts aid in rehearsing for real fights later on in life.

While all age-classes presented forms of play that are often observed during real

fights, adolescents presented these forms in higher frequency and were the only to

present frequent bouts of ‘play-bite’ and ‘wrestle’, which are rougher in intensity

(Flack et al. 2004). The intensification of ‘rough-and-tumble’ play (Fry 2005) with age

has been observed in several primate species (Fagen 1981; chimpanzees: van

Lawick-Goodall 1968; rhesus macaques: Harlow and Harlow 1966), as well as for

males, in comparison to females (baboons: Owens 1975). Rougher forms of play

were not observed when adolescents played with infants, demonstrating they self-

handicapped (discussed in 4.1.2).


45

The observation that ‘play-bite’ and ‘wrestle’ frequently occurred only in adolescent-

adolescent play contrasts results in a study of spotted hyenas Crocuta crocuta (Drea

et al. 1996), who posses shorter developmental periods than chimpanzees. For

hyenas, these two forms were most predominant in infants. Nonetheless, the

intensification of ‘rough-and-tumble’ play also increased with age.

4.1.4 Success and aggression in play

Poirer and Smith (1974) believed that play aids both the sending and receiving

partners in getting acquainted with species-specific and community-specific

communication forms. In this study, metacommunication and social perception skills

were measured through play.

Social play sessions may become so rough that they may turn into real fights, where

one of the individuals would really get hurt (chimpanzees: van Lawick-Goodall 1968;

Hayaki 1985; rhesus monkeys: Symons 1978). Although 6 sDSP (4.05%) and 1 TSP

(3.85%) sessions ended in a negative manner (e.g., scream, flee), none turned into a

real fight during this study. In all these sessions, it was the younger individual who

either screamed or fled [also observed by Symons (1978) in a study on rhesus

monkeys]. Play sessions also included many non-play bouts, which may have aided

in calming down the escalation of roughness during the sessions. Negative

unsuccessful initiations in DSP accounted to only 8.6% of all PP. Positive results in

which a third player joined a DSP occurred more often than not. The overall rate of

success was 8% higher than that observed by Hayaki (1985) in wild chimpanzees.

In the wild, when play ended with one of the players screaming and hitting the other,

one of the mothers would threaten her infant’s playmate. If both mothers were high-

ranking it would sometimes elicit their attacking each other (van Lawick-Goodal

1968). Due to the fact that these chimpanzees were orphaned, I expected to see one

of the older group members intervene, but this never occurred during negative

terminations of play, but only during non-play aggression. The older chimpanzees

may have understood no serious actions were performed, and thus, that there was

no need for an intervention.


46

4.1.5 Dyadic social play initiation categories

Van Lawick-Goodall (1968) observed that play initiation techniques differed

depending on the age variation of the partners. Two year old infants would gently

‘approach’ younger playmates and then lightly ‘tickle’ them, while they would ‘run’ up

in ‘play walk’ or ‘gambol’ and ‘hit’, ‘kick’ or ‘play-bite’ their partner if the latter was of

the same age or older. Juveniles, adolescent females and young adolescent males

would usually initiate play with peers or with younger chimpanzees by simply

‘approaching’ and ‘tickling’. Older adolescent males and adult males would usually

use the ‘play walk’ when initiating play with younger individuals. In this study, results

were different. Infants used mostly ‘locomotion’ (e.g. ‘approach’, ‘run towards’, ‘swing

towards’); juveniles initiated mostly by ‘physical contact’ (e.g. ‘hit’, ‘tickle’), and

adolescents did not present preference between ‘locomotion’ or ‘physical contact’.

Locomotor preferences for infants are explained in subchapter 4.1.6. ‘Approach’ and

‘swing’ were the most frequently observed forms for ‘locomotion’, and ‘jump on’ and

‘grab’ were the most frequently observed forms for ‘physical contact’. Differences

may be due to what is termed ‘cultural variations’ between different chimpanzee

communities (Whiten et al. 2001). This term has been widely used to explain

variations and existence/non-existence of tool using behaviours between

chimpanzee communities.

4.1.6 Lone play categories

One of the theories on the importance of play states that play allows practicing

behaviours and skills that will be needed in adulthood (Loizos 1967; Dolhinow and

Bishop 1970; Lancaster 1971; Fagen 1981, 1993; Smith 1982; Martin and Caro

1985; Fairbanks 1993). Different skills must be mastered during different

developmental stages. Differences viewed between infants, juveniles and

adolescents can then be explained in developmental terms.

As also observed by van Lawick-Goodal (1968) during her study of wild

chimpanzees, in this study, infants’ preferred form of LP was ‘locomotion’. Van

Lawick-Goodall (1968) realized that during ‘locomotive’ play, chimpanzees repeat

their actions several times until the last try when the action is performed better. The


47

author suggested this might present one of the functions of play, in this case being

important in the development of muscular coordination and muscle building. The

author also observed a young chimpanzee dropping to the ground after swinging on

a brittle branch. After that this chimpanzee was more cautious and would test the

branches before swinging on them. This example demonstrates how play-behaviour

can aid a chimpanzee in becoming familiar with its environment and in learning

which branches are safe and which are not during locomotion. Spinner dolphins

have also been observed to use locomotive play in infancy (Martins Silva-Jr et al.

2005), in ways simulating different adult behaviours such as escape. Infants are still

practicing their locomotor skills, getting muscular coordination, and learning to

handle their environment (van Lawick-Goodall 1968; Poirier and Smith 1974; Špinka

et al. 2001).

Research by Schiller (1957) cited in Vanderberg (1978) demonstrated that during

play, younger chimpanzees are unable to perform certain tool-use behaviours.

Nonetheless, juveniles and adolescents must concentrate more on acquiring and

practicing tool-use forms, which is in great part learned through play (Schiller 1957

cited in Vanderberg 1978; van Lawick-Goodall 1967; Bruner 1972; Smith 1982;

western lowland gorillas: Maestripieri and Ross 2004). Individuals must be able to

foresee the possible constituents of objects in order to be able to use them in a

different way (Barsh 1972 cited in Bruner 1972). In this study, juveniles and

adolescents were observed in ‘object’ play more frequently than in other forms of

play, and more frequently than infants.

Chimpanzees build and use tools for a variety of purposes: hygiene, food

preparation and manipulation, and during positive and negative social encounters

(see list with references Appendix ix). The tools and/or the way those are built and

used vary among chimpanzee communities and are non-existent in others, proving

the existence of material culture in chimpanzees.

It is thus important for chimpanzees to explore and practice tool-use for different

ends, and what could be more fun than doing so during play, as observed in several

studies (van Lawick-Goodall 1968; McGrew 1977; Nishida and Wallauer 2003; Sanz

and Morgan 2007). Chimpanzees in this group were observed using tools during LP


48

in forms that could also be used in displays, for investigating frightening and hard to

reach areas, keeping flies away from the body, cleaning the body or other objects, as

comfortable furniture, as weapons, for nut cracking, termite fishing, termite mound

breaking and eating, ant fishing, and during fights (Appendix iv: Object).

Within this group of orphaned chimpanzees, two individuals in particular were

observed using tools more frequently than others, and in very imaginative ways, both

during play and other activities (see Appendices iv, x, xi and for observed use of

objects in non-play and play activities). During LP, Clandestine’s use of objects

accounted to 38.46% of all observed object use in individuals, and Pattex’s

accounted to 30.8%.

Clandestine was fascinated by killing young trees and plants, pushing and pulling at

them, and digging out their roots and trying to replant them. Digging around roots

fascinated Pattex. She would do so with one stick, two sticks held together, or with a

stick and a seed at its end.

Pattex presented great fascination for sound. She would frequently use sticks of

different lengths and diameters (processed accordingly) for ‘drumming’ on different

branches and tree trunks, with her left hand, right hand, foot, holding with both hands

at each end of the stick, and even by holding the stick in her mouth.

Clandestine was greatly fascinated by beetles. Each time she would spot one, she

would catch it, immediately take one wing off so it could not fly away, carry it around

between her thighs and belly, and resume playing with it later. She would then use it

as a ‘tickling instrument’, by allowing it to move around her chest and neck, and

inside her nose, ear, anus and genital regions. This unfortunate ‘tickling instrument’

would induce many ‘laughs’. Play with other animals has also been observed by

Hirata et al. (2001), where chimpanzees toyed with hyraxes.

4.2 Do the orphaned chimpanzees present stable relationships and bonds?

Goodall (1986) classified relationships into four categories: ‘friendly’, ‘unfriendly’,

‘sexual’ and ‘neutral’. ‘Friendly’ relationships are affiliative in nature; ‘unfriendly’ are


49

those of aggressive or avoidance nature; ‘neutral’ are relationships that cannot be

categorized within the former, where individuals rarely interact. Only ‘friendly’ and

‘unfriendly’ relationships are discussed below.

4.2.1 Bianieffe and Clandestine

Bianieffe and Clandestine have been together the longest of all other individuals in

the group (since 2004). Their sDSP was both of the longest average duration and

the most successful. They ranked number 4 in highest frequency of sDSP among all

other possible dyads, while both played more with each other than with any other

individual. Although Clandestine invited Mila to play with her the most, Bianieffe did

invite Clandestine more than any other individual.

During scan samples it was observed that Bianieffe maintained closest proximity to

Clandestine only during ‘feed/forage’. At this time competition over access to the part

of the tree with most fruit could be observed, though not between Bianieffe and

Clandestine. Although the two did not maintain the closest proximity during

movement, on many occasions when other individuals remained in one spot,

Clandestine would follow Bianieffe farther away into the forest, and would always be

the first to agree on following Bianieffe during long travel.

Clandestine would aggress any chimpanzee who would approach an observer or a

‘special’ food source. Nonetheless, she treated Bianieffe differently. She would only

grab Bianieff’s hand while holding a ‘play-face’, then start tickling her in invitation to

play. Only one instance was observed where a play session ended in a negative

form between the dyad. Bianieffe ‘play-bit’ Clandestine pretty hard, and as a result

Clandestine started ‘chasing’ her. Bianieffe responded by screaming and

Clandestine stopped the chase.

If Bianieffe would observe another chimpanzee harass Clandestine (try to steal a

precious fruit from her), she would come to the rescue. In fact, Clandestine was the

only chimpanzee Bianieffe was observed protecting. She would even sometimes

softly bite Mila, if Clandestine preferred playing with Mila over her. An instance of

empathy and altruism was observed when Bianieffe stole a precious fruit from


50

Clandestine during play. Bianieffe climbed up the tree while Clandestine remained

on the ground, crying, hitting the ground, and then throwing a huge tantrum.

Bianieffe stared at Clandestine for a few minutes, then climbed down and offered the

fruit back to Clandestine, who accepted it and invited Bianieffe to play.

Bianieffe and Clandestine’s relationship is ‘friendly’. It falls within the ‘friend’

subcategory, where affiliation is a two-way street. This relationship is the most

supportive and long lasting (Goodall 1986).

4.2.2 Clandestine and Mila

Alongside Clandestine and Bianieffe, Clandestine and Mila were also the most

successful dyad in DSP. Their sessions were of the second longest duration over all

other possible dyads. Clandestine invited Mila the most among all other possible

play partners, and maintained overall second closest proximity to Mila, while Mila

maintained closest proximity to Clandestine only during movement.

At times, when all group members would be waiting on the ground for Mila to climb

off the tree for long travel, Clandestine would ‘woo’ towards her and get closer to

invite her to join the procession. Although Clandestine would at times hit Mila with

her hand or a stick, she was the only one observed carrying her on her back, or lying

while Mila lay hugging on top of her. In most of this occasions Clandestine would be

the initiator of the affection, and sometimes would forcefully make it happen or

maintain it. The only chimpanzees the two would sometimes nest with at night were

each other.

A study performed by Russon and Galdikas (1995) showed that orangutans Pongo

pygmaeus would imitate more those who they had closer and more important

relationships with. Mila was observed imitating Bianieffe’s behaviours, but would

imitate more every behaviour Clandestine made, including agonistic and mischief

behaviours.

Clandestine and Mila’s relationship is ‘friendly’ and falls within the ‘caretaker’

subcategory, common between mother and her infant (Goodall 1986). An eye should


51

be kept open though, since it may be disadvantageous in the long run if Mila

chooses to perform agonistic and mischief behaviours learned from Clandestine.

This will result in danger to observers, group instability, and may even prove

detrimental when joining wild communities. It may also result in maternal abuse of

her offspring, as observed by Maestripieri (2005) in a longitudinal study of rhesus

macaques, and in a human Homo sapiens study (Carroll 1977).

4.2.3 Dolly and Pattex

During DSP, Dolly both played with and invited Pattex the most, although Pattex

invited Dolly the least. Dolly’s success rate in DSP with Pattex was second to that

with Bianieffe, which should not be weighted slightly since Dolly’s success rates with

other individuals were the lowest in the group. Pattex’s close proximity to Dolly

during ‘feed/forage’ was second only to Youbi, which demonstrates her feeling

comfortable with Dolly at times when a situation may become stressful. Overall, Dolly

maintained the farthest distance from Pattex, but in instances of need was the first

by her side. During ground travel Clandestine would always find opportunities to

harass and hit Pattex. Dolly would be the only chimpanzee to intervene in Pattex’s

favour. She would also always put Pattex’s arm over her back, after which they

would travel with Pattex clinging to Dolly’s back fur.

Dolly and Pattex’s relationship is that of ‘friendship’, and can be included under the

‘caretaker’ subcategory, since it is characterized mostly by assistance, protection

and association (Goodall 1986).

4.2.4 Dolly and Clandestine

After Pattex, Clandestine is the individual Dolly played the most with. They both

maintained the second greatest proximity from all other possible dyads, and

maintained closest proximity to each other during ‘rest’. Dolly also maintained

greater proximity to Clandestine during ‘other’. This could be explained in two forms:

1) Dolly would seek out Clandestine for support and reassurance when performing

her stereotypic behaviour; 2) Dolly would frequently seek out Clandestine when the

latter was resting.


52

Dolly is the chimpanzee that arrived in the worst psychological shape at H.E.L.P.

She arrived at an older age compared to the others, after spending several years

living with abusive humans. She had no fur, and would constantly rock while hitting

her chest with her hand and sucking on her lower lip. Today she still sucks on her

lower lip in times of excitement. During these times she searches for an individual

whose arm she can hold. Clandestine is the only chimpanzee who accepts her

approaches for support, and allows her to hold her arm while she calms down.

Although it may seem Dolly has a high need for Clandestine, she is also the only

chimpanzee to challenge her during the latter’s aggressive strikes towards Pattex.

Dolly and Clandestine’s relationship is that of ‘friendship’ but does not fall into any

particular subcategory described by Goodall (1986).

4.2.5 Clandestine and Pattex

Both maintained overall greater distance from each other, and were also the dyad

that maintained greatest distance over all other possible dyads. They both presented

least proximity to each other during ‘rest’ and ‘feed/forage’, and Pattex remained the

farthest from Clandestine also during ‘movement’. This can be explained by what

appeared to be a unilateral rivalry of Clandestine towards Pattex. Clandestine would

constantly harass Pattex during travel on the ground if Youbi was clinging to Pattex.

She would try to take Youbi away from Pattex, and would not stop hitting the latter

until Youbi would accept. Pattex is also the chimpanzee Clandestine would harass

the most during other occasions. In order not to be the subject of abuse, Pattex

probably preferred maintaining greater distances from Clandestine.

Their DSP was one of the least successful among all other dyads, but was third

longest in duration overall, and of longest duration between all possible dyads for

Pattex.

Clandestine and Pattex’s relationship is unilaterally ‘unfriendly’. It seems to fall

unilaterally into the ‘competitive’ subcategory, with Clandestine’s jealousy fits toward

Pattex’s relationship with Youbi (Goodall 1986). It also falls into the ‘hostile’


53

subcategory, for Clandestine’s aggression towards Pattex and Pattex’s avoidance of

Clandestine (Goodall 1986).

Relationships and proximity distances are associated in different ways. Distances

are used in societies in order to regulate interactions, for example, individuals who

are incompatible will prefer maintaining greater distances form each other.

Nonetheless, in some instances individuals may not have the choice and thus live in

close proximity despite their incompatibility, where relationships must then be

shaped accordingly (Kummer 1970). Kummer (1978) has demonstrated that one

individual may learn to predict another individuals’ behaviour under different

circumstances and may then react appropriately. In the case of Pattex, it seems she

preferred to maintain greater distances from Clandestine, who continuously

harassed her in different situations.

It has also been discussed that an individual may try to alter unfavourable

relationships (Kummer 1978), and that play may function to facilitate the integration

of animals into a group (Fagen 1981; Bekoff 1984). Mancini and Palagi (2009)

observed that gelada baboons Theropithecus gelada used play in order to increase

social affiliation and/or for social assessment purposes. If this is so, Pattex may be

trying to change their relationship into ‘friendship’ through play. Pattex invited

Clandestine much more than vice versa, and would move a great distance with the

objective of inviting Clandestine for play. This may have been her way of trying to

bond more positively with Clandestine, in a rather safe and ‘fun’ manner.

4.2.6 Pattex and Youbi

Out of all other dyad combinations, Pattex and Youbi’s sDSP was the second most

frequent. They invited each other an equal amount of times, although they both

invited Mila more, and they both held a second highest success rate when playing

with each other. Youbi was Pattex’s most frequent play partner, while Pattex was

Youbi’s second most frequent play partner. Nonetheless, Pattex’s sDSP with Youbi

was of her shortest average duration, but, in fact, most of Youbi’s sDSP sessions

were of very short duration.


54

Third overall closer proximity was observed between Pattex and Youbi, with Pattex

maintaining closest proximity to Youbi during most activities. During travel, Youbi

would not proceed unless Pattex waited for her. During ground travel, they would

always proceed with Youbi holding on to Pattex’s back fur in a half-hug position.

Pattex was the only individual Youbi would nest with at night, when not nesting on

her own.

Pattex and Youbi’s relationship is ‘friendly’, and falls both within the ‘caretaker’ and

‘friend’ category.

4.2.7 Pattex and Mila

Their sDSP sessions were the third most frequent among all other possible dyads.

During DSP, Mila was who Pattex invited the most and with whom she held the

highest success rate over all other partners. She was observed playing with Mila

only 2 times less than with Youbi. Mila invited Pattex more than Pattex invited Mila,

nonetheless, frequency of her invitations and sDSP with Pattex were second to

Youbi.

Although their DSP relationship was positive, Pattex is the one Mila held the farthest

distance to during ‘rest’ and ‘feed/forage’. Pattex would aid Mila in several occasions

for bridging during movement off the ground, but their relationship did not present

any more care-takering than that.

Pattex and Mila’s relationship is ‘friendly’, and falls within the ‘friend’ category,

although the bond is only observed during play.

4.2.8 Youbi and Mila

Their DSP frequency was highest, and its success rate was the second highest

among all possible dyads. Although Mila invited Youbi more than vice versa, they

both invited each other more often than any other individual, and played more as a

dyad than with any other individual. Youbi’s longest average sDSP duration was

when playing with Mila.


55

They both held closest proximity to each other among all other dyads, and also

maintained closest proximity to each other during ‘movement’, feed/forage’ and ‘rest’.

They are the youngest and closest in age, which may explain their bilateral

closeness in play and other activities. Nonetheless, every morning and every

afternoon, during feeding of milk and porridge, Mila would try to instigate Youbi over

receiving the drink first. Youbi would simply ignore Mila’s calls, and remain clam.

Youbi and Mila’s relationship is that of ‘friendship’. It falls within the ‘friend’ category,

which is both the strongest and lasts the longest (Goodall 1986).

4.3 Individual behaviours - Dolly

Two factors are responsible for an individual’s behaviour: the inherited (genetic) and

the environment in which an individual grows (Bateson 1976). Lorenz (1965)

separated the experiences into those acquired through learning, and those

necessary for normal behaviour, that when withheld, damage the individual.

A study by Haskett and Kistner (1991) showed that physically abused human Homo

sapiens children participated in and initiated less positive social interactions than

non-abused children, and that non-abused children did not respond to abused

children’s positive social interactions very frequently. Dolly presented the lowest

frequencies of participation in sDSP. She presented the second lowest frequency in

LP, and played much less than her juvenile companion Pattex and her older

companion Clandestine. It was observed that many times Dolly would initiate play

with younger individuals in a very abrupt manner, by hitting or jumping on them in a

hard and harsh manner. This appeared to frighten her companions, who would

scream and run away. Her success rate in dyadic social play was the lowest in the

group. She was also the least invited play partner.

Dolly presented the highest ‘non-active’ counts, and lowest ‘social’ and ‘non-social’

activity counts. In fact, her ‘non-active’ counts were higher than her ‘active’ counts


56

(see Appendix xii). She was also the only group member to present stereotypic

behaviours (view 4.2.4), and the only ‘human’ biter in the group.

Past studies have demonstrated how early experiences influence behaviours both in

the short- and long-term (Suomi 1997). It is known that Dolly’s life prior to arrival at

H.E.L.P. was that of severe abuse (Aliette Jamart and Noël Kiyindou, personal

communication). Studies on rhesus macaques and chimpanzees (Mason 1961;

Harlow and Harlow 1969; Rogers 1973) demonstrated that poor socialization

experiences in infancy result in deficits in social relationships later on in life, including

social play deficits and higher aggression. Human Homo sapiens studies have

proven physically abused and neglected children to be less social than non-

maltreated children, physically abused children to display more aggressive

behaviours and neglected children to be more solitary (Prino and Peyrot 1994).

Furthermore, a study in human children has also demonstrated abused individuals to

be less exploratory, venturous and eager to learn (Aber and Allen 1987), which

explains Dolly’s low levels of play behaviour in general, and low levels of activity. It

also explains Dolly’s reluctance to build day and night nests. Although observed to

be able to perform the task, she was never observed to build day nests and was

often observed sleeping in old nests built by her peers.

Nonetheless, studies by Harlow and Suomi (1971), Chamove (1978) and Novak

(1979) on rhesus macaques and baboon, have demonstrated that initial differences

from more socially adapted individuals do disappear after a long time of living and

interacting with more socially adapted individuals. In a study performed on abused

human children, both initiation and sociability levels increased in peer group

play/social settings (Strain et al. 1977; Fantuzzo et al. 1987). Keepers/observers who

have worked with Dolly since her arrival have observed this change as well. Upon

arrival Dolly not only presented much frequent and pronounced stereotypic

behaviours (view 4.2.4) but was also unable to relate to her peers. Her peers

appeared to be frightened of her, and she did not know how to initiate interactions.

When others were at play she would run over, bite or hit one of the players, and run

away (Noël Kiyindou, personal communication).


57

Dolly presented the highest levels of submissive and reassurance behaviours

towards observers, and would also avoid them more frequently. This has been

observed in abused children, where higher levels of insecurity, especially insecure-

avoidant relationships, were present even after being fostered (Lamb et al. 1985).

Although Dolly’s lone and social play behaviour is poor compared to her peers’, her

behaviour has notably improved over time both as an individual and socially (Noël

Kiyindou, personal communication), and given time, may improve even more.

Furthermore, her stereotypical behaviour does not include self-harming, which would

be indicative of not being able to experience feelings of sadness, anger and anxiety

(Simpson 2001).

A major determinant of release success should be measured in the future, that of

mother-infant relationship. A study on humans (Alessandri 1992) has indicated that

abused mothers were less involved and more negative with their offspring than non-

abused mothers. This was translated into the behaviour of the children. Children with

abused mothers displayed lower levels of cognitive play (more simple manipulative

forms of play rather than more constructive and symbolic play). They were also less

positive in their social behaviour and presented higher levels of aggression than

children with non-abused mothers.


58

Chapter 5. Conclusions and recommendations ___________________________________________________________________

5.1 Species-typical play behaviour

There did not appear to be any overall difference in play behaviour between the

orphaned chimpanzees and chimpanzees living in wild troops or in captive setting

where both mothers and adults are present. Although more specific differences may

have been found if measured by sex differences, these were not evaluated due to

lack of males in the group.

The chimpanzees in this group are likely using play for both short-term and long-term

benefits. Long-term benefits are likely in the forms of locomotive and object skills

acquisitions, and through relationship formations and social skills acquisitions. Short-

term benefits were observed at the individual level. As observed in various primate

studies (van Lawick-Goodall 1968; Lancaster 1971; Goodall 1986; Paquette 1994;

Palagi et al. 2004, 2006, 2007), it appeared that the individuals in this study used

play in order to reduce confrontation during stressful situations, for example:

o During ground travel in the morning and the afternoon, right before arrival at

the supplemental feeding spot, all individuals would begin playing with each

other and on their own, possibly to reduce tension associated with the onset

of feeding.

o While attempting to acquire an object or precious food item in possession of

another individual.

o In order to get the attention of an individual, when the latter paid attention to a

different individual.

5.2 Relationships

The orphaned chimpanzees live in a cohesive group, where altercations are

practically none existent. Most individuals maintain strong relationship bonds with all

of their peers, although differing in quality and form. Only one dyad presented an

unfriendly relationship, which may still change over time.


59

5.3 Individuals

Dolly’s need for reassurance while performing her stereotypical behaviour and in

general should be taken into account by the keepers/observers, who should allow

her to grab their arm when asked by her, and reassure her when she demands

reassurance from them. They should also try to distract Dolly when she begins

performing her stereotypical behaviour next to them, with tickles or groom. It seems

to aid in lessening the frequency of her abnormal behaviour and in significantly

reducing its duration (Halit Khoshen, personal observation). At this time only one

keeper/observer, Noël Kiyindou, is following these rules, while the others either

ignore or negatively react to these approaches.

5.4 Evaluation of methods

Overall, analysis of play behaviour has demonstrated the cohesiveness of the group

and the good metacommunication and social perception skills of the individuals

(Bateson 1955; Altmann 1962; Dolhinow and Bishop 1970; vervet monkeys

Cercopithecus aethiops: Fedigan 1972), as well as the ‘normal’ advances in skill

acquisition behaviours of the individuals. Play has also demonstrated to be a good

indicator of previous/current psychological issues in individuals and has proven

invaluable in evaluating relationships.

Proximity measurements for different activities were invaluable in analyzing

relationships between dyads and in signalling out individual psychological issues.

Nonetheless, relationship bonds would not have been well represented if not

analyzed by coupling proximity measurements with detailed play behaviours and

qualitative data.

Most studies conform to quantitative data, where behaviours and relationships are

represented in numbers, and communities are looked at as one lump. Although I do

not deny the importance of such, I believe that qualitative data, often referred to as

subjective data, are as valuable when performing relationship and individual

behavioural studies. In some instances, the quality of a specific behaviour may even

override its low/high quantity. In this study, where quantitative and qualitative


60

measures were used in conjunction, more complete and precise pictures on

relationships and individual behavioural issues were obtained.

5.5 Future research

I recommend following up every year with the methods used by this study. Changes

and/or strengthening in relationships may be observed over time, especially due to

age increase. Some of the relationship types may be due to age-class differences or

unavailability of more similar age-class members in the group. Over time all of the

orphans will be part of the same age-class, thus differences from present

relationships may be more pronounced.

Release initiatives should not conclude stereotypic and other abnormal behaviours to

be determinants of an individual not being suitable for release before opportunity and

time are available to the individual to change these behaviours. They should stress

and encourage positive social interaction with peers prior to release for a longer

period of time. Changes in behaviours should be closely monitored.

As welfare advocates maintain, each individual is valuable. This should also be

applied in the conservation field. As Bekoff (2010, pg. 25) put it: “we need to focus

on solutions that advocate the well-being of individual animals and not allow them to

be harmed or killed for the good of their own or other species”. Although the words

were written in a different context, these also apply to release. Pre-release

monitoring and selection of release candidates should be performed over a long

period of time (years), and evaluate each individual in context of self and its

relationship to other group members in order to make informed decisions on

necessary training, socialization and readiness for release. This way, casualties

post-release may be lower, and release success rate higher.

In order to view if play behaviour, relationships and individual personalities can lead

to conclusions over survival, interactions and success after full release, post-release

observations should be carried out. If a relationship will be found over survival,

altruism and partnership at that time, this method will allow release initiatives to be

able to predict more accurately future outcomes during pre-release monitoring, and


61

also react on time in order to modify specific unwanted behaviours. Post-release

monitoring must also evaluate success at the individual level, and strive to identify

the reasons why some individuals are not successful by evaluating their past

histories.


62

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Appendices ___________________________________________________________________

Appendix i: Play ethograms

Table 6. Dyadic social play initiation categories ethogram

Category Definition Examples Physical

contact Involves body contact Grab, pull, tickle, push

Gestures Involves the use of facial and/or bodily gestures

Extend hand towards, drum belly, move head up and down

Locomotive Involves the use of movement and gymnastics

Swing next to, somersault, run towards, approach

Object Involves the use of an object Hit with object, move liana, throw branch at

Combination The use of two or more of the above categories

Swing and grab, jump towards with play face

Table 7. Third-party intervention forms ethogram. The first 4 forms were based on Hayaki (1985), the fifth was observed for the first time during this study.

Form Definition Joining A third party joins the session Replacement A third party joins the session and one of the original players

leaves Interruption A third party’s arrival results in the end of the play session Continuation A third party joins and then leaves, while the original play

partners continue playing Invitation One of the DSP partners invited a third party to join


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Lone and social play categories and forms ethograms were adapted from Nishida et

al. (1999) and Goodall (1989).

Table 8. Lone play categories ethogram

Category Description Examples Locomotor play Involves movement and

gymnastics Somersault, jump, swing, pirouette

Nest play Involves playing in making or with sleeping nest

Object play Involves the use of an object Drum with stick, play with mud, play with termite mound

Imaginary play Involves an imaginary individual or object

Self play Involves playing with one’s own body without an object

Tickle self, drum on belly

Table 9. Social play forms ethogram

Form Description Catch hand One individual offers its hand the second tries to seize it

Catch object

An individual offers a stick/branch/liana or hits with it next to its play partner, while the other tries to grab it

Chase Two or more individuals pursue one another while running Climb on An individual mounts on the body of its play partner Drag Pull along the ground another individual Fencing The use of branches/sticks in the as if practicing a fight through

fencing as human primates do Grab Seize another individual’s body part Grapple Both individuals’ arms and/or feet are locked, and sometimes roll

together on the ground. Hand in mouth

Place fingers or whole hand in the mouth of play partner

Hit Strike a partner with hand(s) or/and feet, or with an object (eg. liana, branch)

Hit ground Strike the ground with hands or sticks Hold hand Grasp the hand of playmate while the latter performs another activity

or while holding play-face Hug Embrace, usually front-to-front Jump on The use of four limbs to jump on the body of playmate Jump over The use of four limbs to jump over the body of a playmate Place exchange

One individual jumps up higher on the branches, while the other jumps lower on the branches, while both take each others’ spot


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Play with object

Play with an object, such as a termite mound, together

Play-bite Gentle biting resulting in tickling Pull Tug play partner’s body part while holding it Push Push body of play partner with hands or feet Run Quick bipedal or quadrupedal locomotion Slap hands together

An individual uses her/his palm to slap partner’s palm

Somersault Rolling head over heals. Swing Dangle together, one next to the other, or alternating (when one

swings up the other swings down) Tickle Putting one or both hands on a body part, usually in the groin or

between the neck and shoulders, and making tickling movements with the fingers.

Touch Reach out with fingers or hand and hold them pressing on playmate’s body

Wrestle Mutual grabbing hold and tickling, play-biting, jumping on… while maintaining body contact, may also involve rolling


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Appendix ii: Unsuccessful initiation forms (para-play)

Dyad Initiation form Outcome Y2M Mila is swinging. Youbi invites Mila by

trying to catch her on the swing After catching Mila, Youbi starts swinging in Mila's place

Y2B Youbi offers Bianieffe her foot for grab/pull

Bianieffe remains next to Youbi. Both rest in nest

P2C Pattex approaches Clandestine with a branch in her hand and play-face

Clandestine accepts but Pattex changes her mind and leaves

P2C Pattex invites Clandestine by swinging over her

Clandestine gets mad, throws her arms up towards Pattex in order to scare her away. Pattex gets scared and runs away. Clandestine shakes branches on which Pattex is moving in order to make her loose balance and fall

B2C Bianieffe is interested in the alablanquia fruit Clandestine is holding. She performs a mini display inviting Clandestine to play with her. That way she has better chances of stealing the alablanquia

Clandestine performs a play display back at Bianieffe and then moves away

M2C Mila jumps on Clandestine Clandestine pushes Mila away M2D Mila swings towards/into Dolly's face Dolly grabs Mila and places her next

to her All Ignore C2B Clandestine somersaults back and

forth, grabs branch and hits Bianieffe while holding play-face

Leave

D2C Dolly hits a liana against tree trunk next to Clandestine

Leave

M2Y Swing next to Leave P2M Grab Leave P2M Hit gently Leave P2B Shake liana where Bianieffe is sitting Leave P2M Run towards Leave Y2M Reach for arm Leave Y2P Extend hand towards Leave Y2P Behind upwards while moving branch

in one hand and grabbing/pulling with the other hand

Leave

C2M Clandestine jumps forwards and backward in a small display while holding a play-face

Leave


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C2M Clandestine throws a branch at Mila Mila whimpers and asks to be carried. Clandestine hugs Mila and puts her on her back

D2P Dolly hits Pattex very hard Pattex follows Dolly but stops C2P Clandestine invites Pattex for play

through hitting a tree trunk and scrubbing her back on it

Pattex accepts and starts running in order to play chase. Clandestine does not want to play chase and does not follow

D2P Dolly initiates by hitting Pattex very hard

Pattex yells angrily at Dolly

D2P Dolly jumps on Pattex in a rough manner

Pattex yells at Dolly and chases her away. Dolly runs away

Y2M Youbi approaches and grabs Mila's hand

Youbi changes her mind and leaves

Y2B Youbi approaches Bianieffe with play-face

Youbi changes her mind and leaves

D2Y Dolly pulls Youbi hard Youbi screams C2Y Clandestine jumps forwards and

backward in a small display while holding a play-face

Youbi starts grooming Clandestine

Legend: B=Bianieffe, C=Clandestine, D=Dolly, P=Pattex, Y=Youbi, M=Mila, 2=invites


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Appendix iii: Negative endings in dyadic social play

Dyad Description Clandestine and Pattex

Clandestine gently hits Pattex from behind. The action scares Pattex who jumps and leaves

Clandestine and Pattex

Clandestine hits Pattex too hard, Pattex leaves

Clandestine and Pattex

Clandestine begins playing too roughly, Pattex screams and climbs higher away from Clandestine

Bianieffe and Clandestine

Bianieffe play bites Clandestine too hard, Clandestine chases her. Bianieffe believes Clandestine is going to retaliate and screams. Clandestine stops chasing Bianieffe

Youbi and Mila Mila screams, Youbi stops playing Pattex and Mila Pattex hits Mila, Mila screams, Pattex stops


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Appendix iv: Lone play forms

Description Players Combination

Swing while eating breakfast fruit Dolly Head between legs, standing bipedally, grabs a branch and moves it from side to side

Mila

Jump up and down collecting branches Mila Move foot up and down hitting tree trunk. At the same time arm swings up and down while holding a branch with leaves and hitting tree trunk with it

Mila

Swing with piece of dead tree trunk in hand while hitting tree trunk with it Mila Swing held by one hand, holding a branch in the mouth and another in the other hand. The branch in the hand is used to touch and move other branches

Mila

Swing while moving branch with leaves in hand Mila Common sequence: Swing, jump down, climb up, head between legs while standing bipedally, jump down, swing, jump down and run, hang upside down and let body fall down, swing, jump down, pirouet while running from one side to the other, locomote from liana to liana 'tarzan' style, jump down, grab liana with foot and move from side to side, grab liana with hand, pull and push, run on lianas, swing

Pattex

Swing with one hand while softly touching and hitting plants Pattex Swing up and down while hitting tree trunk Pattex Swing with branch in hand Youbi Touch and grab branches bellow her while swinging Youbi Move hands from side to side, touching and moving branches and leaves found on the way

Youbi

Swing while catching and moving plants from side to side Youbi Swing while moving branches with leaves from one side to the other Youbi

Self Move finger inside her anus in a tickling fashion Clandestine Play with own foot in her hand Pattex

Self Play at making a nest out of lianas Clandestine Play at building a nest with very short and small branches Mila Roll in nest Mila Tap foot on ground of nest Mila

Locomotor Somersaults on lianas Clandestine Swing and jump from one liana to another, using one hand Clandestine Jump down Clandestine Swing from one broken tree to another Clandestine Swing 'tarzan style' on liana, head and stomach up, holding on with both hands and feet

Clandestine


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Swing 'tarzan' style while holding liana with one hand Clandestine Swing, fall and climb again Clandestine Somersaults on the ground Clandestine,

Mila Jump from one liana to the next, climb down and up, jump down and up Dolly Swing from side to side and up and down Dolly,

Pattex, Youbi, Mila

Move arms and hands from side to side Dolly, Youbi Move from one liana to the next 'tarzan' style Mila Swing and stamp feet on tree trunk Mila Swing while hanging with one hand Mila Swing while rolling around Mila Alternating swinging with jumping down, climbing up and then swinging again

Pattex

Jump from one branch/tree trunk to the next Pattex Swing back and forth while holding with both arms and legs, 'tarzan' style Pattex Swing head down, held by feet Pattex Swing side to side and up and down while sitting on liana ('human swing' style). Prompted by holding hand on a stable branch

Pattex

Swing upside-down Pattex Roll around tree trunk from side to side Youbi Hang upside down moving from side to side Youbi Jump up and down on a tree Youbi Swing up and down, being prompted by branches bellow and above her Youbi, Mila

Object Tangle hand in thin liana, which would produce strong laughter (tickle) Bianieffe Ant play: Hit with hand where ants hide inside a fallen tree trunk, squash ants that come out. Stick manufactured branches in holes, move from side to side and in circling motion, take branches out, look for ants, smell branches

Clandestine

Beetle game: Catch beetle, immediately take one wing off so it could not fly away, and then carry it around between her thighs and belly until she felt like playing with it. She would then use it as a tickling device, by allowing it to move around her chest and neck, and inside her nose, ear, anus and genital regions. This poor tickling instrument would produce many laughs.

Clandestine

Break branch and drag over a liana Clandestine Break plans and put in mouth (no eating), clean behind with plant parts, look at it and throw on ground

Clandestine

Clean with hand, stick and by blowing on, a fallen dead tree trunk Clandestine Collect, move, assemble and reassemble thick branches in X position Clandestine Cut and crush leaves Clandestine Cut leaves and put pieces in and out of her nose Clandestine


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Cut leaves, chew and spit out Clandestine Dig holes in ground with hand Clandestine Dig out treasures from underneath the ground (eg. seeds, insects) Clandestine Dig out, pull out and try to replant young trees and plants Clandestine Dig young tree out of ground, move from side to side and shake harshly to loosen

Clandestine

Explore what to do with objects found on the ground Clandestine Grab branches with leaves, touch, destroy and throw away Clandestine Hit ground Clandestine Hold poga fruit in hand, and let fall into mouth over and over again while laying on her back

Clandestine

Jump up and down while holding play-face, hitting with hands and feet inside a recently opened (by her) hole

Clandestine

Move liana from side to side, from hand to hand Clandestine Move objects on the ground Clandestine Move plants from side to side Clandestine Open holes in ground using her foot Clandestine Play around with roots pulled from under trees Clandestine Play with dry termite mound: Try to squash with feet, throw down as a ball on different surfaces, manufacture and stick branches of different lengths into it, push it as a football on the ground (using hands and feet)

Clandestine

Play with poga fruit as a jumping ball and in burying it in the ground Clandestine Pull out a young tree from its roots Clandestine Push sticks into holes of dry termite mound Clandestine Put and remove a seed from a leaf over and over again Clandestine Remove tree bark from fallen tree trunk with ants inside, put a stick through a hole, remove, look at it, remove dirt from tree trunk with a leaf, grab another stick and look for a hole to put it through, try to insert in different sized holes, hit ground and tree trunk with hands trying to smash ants, dig with fingers in the ground, hold a leaf tightly on the tree trunk, remove and look to see what stuck on the leaf, crush and break leaf into peaces, grab another stick and put through holes, remove and put stick in mouth (but it had no ants on it), repetitive insert and pull out stick from holes while turning the stick around inside the holes, discard stick and pick up another one, try to put in hole but it is too thick so tries with force

Clandestine

Replant small trees and plants Clandestine Shake branches from one side to the other Clandestine Soil play: Dig in ground, hit soil that comes out of the hole Clandestine Squash seeds against tree trunks Clandestine Squash seeds with branch Clandestine Squash, move and put big seeds in mouth Clandestine Squashing seeds against tree trunk Clandestine


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Termite mound play: Hit termite mound with seed. Squash against ground with foot. Grab and throw as a ball from one hand to the other. Throw on the ground like a ball, recover and throw again. Sit on the termite mound. Kicks termite mound backwards supported by hands and one foot on the ground. Grab termite mound, throw and squash against ground, kick again. Throw against ground again. Take a branch and try to fit it in termite mound's holes. Throw against ground. Put foot over termite mound with pressure in order to break it. Grab and throw on the ground. Put termite mound against her eyes to see if anything is inside the holes. Climb on termite mound. Sit on it and try to squash it by pressuring with her behind on it. Remain sitting on termite mound. Lay face down and with arms behind her throws termite mound on top of her. Throws it against the ground again. Holds it with feet, puts sand over it and cleans with hand. Throws it against fallen tree trunk where it finally breaks. Cleans termite mound soil from fallen tree trunk. Grabs remaining termite mounds and tries to insert sticks into it and to crash it while sitting on top of it

Clandestine

Try to tie up a show made out of roots Clandestine Use alablanquia fruit as a ball, throwing it up and down with hands Clandestine Use stick to open holes in fallen dead tree trunk Clandestine Use stick to open holes in the ground Clandestine Clean tree trunk with branches Clandestine,

Pattex Cut a branch into small pieces with hand Dolly Cuts branches into small peaces with foot Dolly Hit tree trunk with a piece of wood Dolly Use branch to dig hole in ground Dolly Move lianas or branches from side to side while touching or hitting branches and leaves with stick, leaves or tree trunk with it

Dolly, Pattex

Use stick to move mud around in swampy waters Dolly, Pattex, Youbi

Move liana or branch: back and forth, below and above body, and from side to side, with feet or hands

Dolly, Pattex, Youbi, Mila

Drumming with hands, feet or branches on tree trunks, branches and lianas

Dolly, Youbi, Mila

Nail branch into the ground Dolly Hit branches bellow her Mila Hit tree trunk with one foot 'display' style Mila Stand quadrupedally and hit branch held in hand Mila Use branch held in hand to hit other tree branches Mila Cut off plants from underneath her while hanging upside-down Pattex Dig around young trees, searching for treasures. Dig with hands, branches, two branches held together, a branch and a seed at its end, etc…

Pattex

Dig out tree roots Pattex


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Drumming: Use sticks of different lengths and diameters (she would process them accordingly) for drumming on different branches and tree trunks, with her left hand, right hand, by holding with both hands at each end of the stick, with her foot, and even while holding the stick in her mouth.

Pattex

Fan over her face and body with an old branch with dry leaves Pattex Hanging upside down, grabbing plants from below her and moving leaves with her hand

Pattex

Hit sides of tree trunk with alternating or/and both hands Pattex Hit tree trunk with hands Pattex Move and bend liana branch Pattex Move hand from side to side while touching and grabbing leaves Pattex Move tree trunk from one side to the other Pattex Scrape branch with leaves against tree trunk Pattex Scrape tree trunk Pattex Stick catch game: Holds a thin liana in her hand, moves it from side to side, grabs it with her foot, takes it away from her foot with her hand, grabs it with her foot again, takes it away from her foot with her hand.

Pattex

Taps with hand on branches above her and on tree trunk Pattex Touch and move leaves Pattex Try to stick a branch inside holes found on a tree Pattex While sitting on top of a dead tree trunk (which is still standing), scrapes off pieces of the tree trunk and its shells

Pattex

Collect and move leaves Youbi Cut and grab a bunch of branches with leaves, cut off leaf by leaf Youbi Hit tree trunk with a branch Youbi Hold liana in hand and move from side to side, while hitting branches with it

Youbi

Move branch with leaves from one side to the other, hitting own back Youbi Move tree bark from side to side Youbi

Pull and push liana and branches Youbi Touch and grab branches and leaves Youbi, Mila


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Appendix v: Initiation forms

Description Dyads Combination

Approach with branch in hand P2C Behind upwards while moving branch in one hand and grabbing/pulling with the other hand

Y2P

Jump towards offering foot for grab/pull M2P Jump up and down with play-face C2P, C2M Move branch and hit D2P Move branch while looking at possible play partner Y2B, M2P Run towards, hit, and run away inviting chase B2C Swing above offering feet for grab M2P Swing and grab Y2P, T2M, P2C Swing and hit below with feet Y2D Swing and touch B2P, Y2P, Y2M

Gestures Drum belly Y2P Extend hand towards Y2P, M2P, M2B, Y2P,

Y2C Flirt M2D Head under body, head between legs M2P, P2M, M2Y Look at possible play partner from above M2P Move head up and down P2Y Offer foot for grab/pull B2Y, Y2B Play display, jumping back and forth C2Y, C2M Present body part for grab M2P Reach for body part Y2P, Y2M

Locomotive Approach B2C, B2P, B2M, C2M,

C2D, D2M, D2P, M2P, Y2P, M2Y, Y2M, P2C, P2M, P2Y, Y2D, Y2B

Chase P2C, D2P Escape in invitation for chase B2C Jump towards D2B, P2Y Run towards B2C, P2M Slide towards Y2P, Y2B Somersault towards C2B Swing down to reach possible play partner without touching

M2Y, M2D

Swing next to, over, or above Y2M, P2M, M2Y, M2P, P2C, M2D


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Object Extend branch to possible play partner P2Y Grab branch where possible play partner swings Y2M Hit gently with branch or liana Y2B, D2P, Y2P Hit ground next to possible play partner B2C Hit lightly with branch Y2P Hit tree trunk and scrub back against it C2P Hit tree trunk or thick liana with hand C2P, C2M, D2C, P2Y Hit tree trunk with liana or branch near possible play partner

C2D

Hit with branch in direction of possible play partner P2D, P2Y Hit with branch or liana in the air, close to where play partner is located

P2Y

Hit with liana and extend it for possible play partner to grab

D2P, D2M

Move branches next to M2C, P2B Move lianas on which possible play partner is sitting P2B Shake tree trunk where possible play partner is located C2M Stamp on ground next to B2C Throw branch at C2P

Physical contact Grab body part B2Y, Y2M, P2Y, C2P,

P2M, Y2M, M2Y, Y2M Grab/pull P2M Hit gently with hand P2M, D2M, M2Y, P2Y,

Y2M, P2B, P2B, D2C, M2P

Hit hard with hand D2P Hug whole body (with arms and legs) and gently play-bite on shoulder

C2D

Jump on B2C, C2M, M2C, M2P, P2Y, Y2M, Y2P, Y2B, B2P, P2C, M2C, D2P

Jump on and gently touch and pull D2P, D2M Jump on and hug B2C Pull and tickle C2B Pull body part P2Y, Y2B, D2M, Y2P,

D2Y Push gently C2P Tickle C2M, Y2P Touch C2Y, M2P, D2B, M2D,

P2Y, B2C, D2C

B=Bianieffe, C=Clandestine, D=Dolly, P=Pattex, Y=Youbi, M=Mila, 2=invites


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Appendix vi: Number of sDSP bout forms within a session

Total AA (n=1) AJ (n=4) AI (n=4) JJ (n=1) JI (n=4) II (n=1) Number

of bout forms F Mean

% F Mean % F Mean

% F Mean % F Mean

% F Mean % F Mean

%

1 26 19.26 1 10 4 18.18 4 21.05 3 100 10 19.23 4 13.79 2 34 25.19 1 10 5 22.73 6 31.58 17 32.69 5 17.24 3 19 14.07 1 10 2 9.09 3 15.79 8 15.38 5 17.24 4 6 4.44 2 3.85 4 13.79 5 17 12.59 1 10 3 13.64 1 5.26 8 15.38 4 13.79 6 13 9.63 2 20 4 18.18 2 10.53 2 3.85 3 10.34 7 7 5.19 2 20 2 3.85 3 10.34 8 6 4.44 2 20 2 9.09 1 5.26 1 1.92 9 6 4.44 1 4.55 2 10.53 2 3.85 1 3.45 10 1 0.74 1 4.55

Number of different bout forms in a session were calculated only when complete

sessions were recorded: AA=Adolescent+adolescent dyad, AJ=adolescent+juvenile

dyad, AI=adolescent+infant dyad, JJ=juvenile+juvenile dyads, JI=juvenile+infant

dyads, II=infant+infant dyads; N= represents the number of possible dyads for the

age-class combination; F=frequency.


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Appendix vii: Play forms in triadic social play

Triad Grab Pull Tickle Touch hit Chase Swing Hug Push Wrestle Kick Jump on Grapple Play-

bite B+D+Y 1 1 2 1 1 B+P+Y 1 B+P+M 1 1 1 1 1 1 1 B+Y+M 2 2 2 1 3 3 1 C+D+P 1 1 1 C+P+M 1 1 1 C+Y+M 1 1 1 D+P+Y 1 1 1 D+P+M 1 1 1 1 1 1 D+Y+M 1 1 1 P+Y+M 7 6 3 4 1 2 2 1 2 1 Total 15 14 11 8 7 5 5 4 3 2 1 1 1 1

Percentage out of total 19.23 17.95 14.10 10.26 8.97 6.41 6.41 5.13 3.85 2.56 1.28 1.28 1.28 1.28

B=Bianieffe, C=Clandestine, D=Dolly, P=Pattex, Y=Youbi, M=Mila


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Appendix viii: Triadic social play interactions

TSP dyad F Mean

percentage Original

dyad Joined

by F Observations

B+D+Y 2 7.69 B+Y D 2 B+P+M 1 3.85 B+M P 1 B+P+Y 1 3.85 Y+B P 1

M+Y B 2 B+Y+M 4 15.38 B+M Y 2

C+D+P 2 7.69 P+C D 2 C+P+M 1 3.85 C+M P 1 C+Y+M 1 3.85 C+M Y 1 C invited Y to join the play

session D+P+Y 1 3.85 P+Y D 1 D+P+M 1 3.85 D+M P 1 D+Y+M 1 3.85 Y+D M 1

Y+P M 3 Y+M P 1 P+M Y 5

P+Y+M 11 42.31

n/a n/a 2

B=Bianieffe, C=Clandestine, D=Dolly, P=Pattex, Y=Youbi, M=Mila; F=frequency.


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Appendix ix: Object use in wild chimpanzees

Object use References Hygiene, health and comfort

Cleaning of body Boesch and Boesch 1990; van Lawick-Goodall 1968, 1973; Sanz and Morgan 2007

Grooming van Lawick-Goodall 1973 Self-medication Wrangham and Nishida 1983; Huffman 1997; Huffman

and Hirata 2004 Keeping flies away from the body

Sugiyama 1969; Sanz and Morgan 2007

Comfortable furniture

Alp 1997; Hirata et al. 1998

Agonistic and non-agonistic social activities To get the attention of others

McGrew 1992

Courtship Whiten et al. 2001 During play (social and lone)

van Lawick-Goodall 1968; McGrew 1977; Nishida and Wallauer 2003; Sanz and Morgan 2007; Hirata et al. 2001

As weapons van Lawick-Goodall 1968; Sugiyama 1969 Pounding and displaying

van Lawick-Goodall 1968; Sugiyama 1969; Boesch and Boesch 1990

Reaching and processing food Ant dipping van Lawick-Goodall 1968; Boesch and Boesch 1990;

Humle and Matsuzawa 2002; Sanz and Morgan 2007 Nut cracking and emptying

Boesch and Boesch 1982, 1990; Boesch-Achermann and Boesch 1993; Matsuzawa 1994

Drinking water van Lawick-Goodall 1968, 1973; Matsusaka et al. 2006; Sanz and Morgan 2007

Honey extraction and bee killing

Boesch and Boesch 1990; Stanford et al. 2000; Sanz and Morgan 2007; Boesch et al. 2009

Termite fishing van Lawick-Goodall 1968; Suzuki et al. 1995; Sanz et al. 2004; Sanz and Morgan 2007

Hunting Pruetz and Bertolani 2007 Other

Investigating scary and hard to reach areas

van Lawick-Goodall 1968, 1973; Sanz and Morgan 2007


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Appendix x: Object use in non-play activities by the orphaned chimpanzees

Description Who used it Anger management

Hit tree trunk with hands and feet, cut a bunch of leaves and chew in a rough manner

Dolly

Cleaning Remove debris and soil from tree trunks with the use of hands, leaves or sticks

Clandestine

Communication Tap ground with thick branches to call others during travel Clandestine Tap on ground with hands and feet to call others Bianieffe, Pattex,

Clandestine, Dolly Move branch up and down to call others during travel Pattex Display Drum on tree trunk with hands and feet while alternating with jumping up and down

Clandestine

Balance on liana, reach tree trunk, hit tree trunk with alternating hands

Dolly

Hit ground with thick branches next to other individuals Clandestine Exploration Explore dead beetle Bianieffe,

Clandestine Furniture and comfort Collect thick branches, put in X position, and use as a chair Clandestine Use soft branches with leaves as cover sheet when resting Pattex and Youbi Hygiene, cleaning and beauty Use small branch with leaves to remove rain water from body Dolly Use leaves to clean inside nose Clandestine Use stick to find buggers in nose (and eat them) Clandestine Use leaves to clean inside eyes Clandestine Use leaves to wipe off faeces of own body and peer's body Clandestine Try to tie hair in back of head with a stem Clandestine Use leaf to hold tight a moving tooth wile trying to get it to loosen more

Clandestine

Make nest Collect nest material, travel with nest material, redo old nests, make new nests

All

Other Move branches Bianieffe Move branches Bianieffe


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Dig and find antibiotic roots, offer to observers Clandestine Hit left and right of own back with long tree bark piece Clandestine Collect leaves and other plant parts and offer observer as a 'permission' present

Bianieffe, Clandestine

Bite on plant, but not eat Mila Move branches around a live termite mound Youbi Cut branches Youbi Do something with branches Youbi Other agonistic / Mischief Throw branches and tree trunks on observers Clandestine Throw faeces on observers Clandestine Hit peers with branches and tree trunks Clandestine Shake tree trunk or branch where peer is sitting or climbing Clandestine


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Appendix xi: Object use in dyadic social play sessions by the orphaned chimpanzees

Description Playing dyad Fencing with branches Bianieffe and Youbi

Hit play partner with liana Clandestine and Dolly Grab branch or liana where play partner swings, or move it in swinging motion (swinging play partner)

Clandestine and Pattex, Youbi and Mila

Offer or hit next to partner with branch, partner tries to grab it

Dolly and Pattex, Pattex and Youbi

Play together with termite mound, searching inside, trying to break it, using as a ball

Youbi and Mila


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Appendix xii: Activity budgets

Within and between age-classes (Tables 10 and 11):

‘Activity’ counts were higher than ‘non-activity’ counts in total (χ2=44.653, df=1,

p≤0.001), for juveniles (χ2=4.052, df=1, p≤0.01), infants (χ2=54.872, df=1, p≤0.001),

and adolescents (χ2=4.651, df=1, p=0.05). ‘Non-social’ activity counts where

significantly higher than ‘social activity’ counts in total (χ2=405.313, 1, p≤0.001), for

adolescents (χ2=181.355, df=1, p≤0.001), juveniles (χ2=184.889, df=1, p≤0.001),

and infants (χ2=66.122, df=1, p≤0.001).

Significant differences were observed between age-classes for ‘non-activity’

(χ2=10.958, df=2, p≤0.01), ‘activity’ (χ2=8.289, df=2, p≤0.05) and ‘social’ activities

(χ2=49.003, df=2, p≤0.001). Infant’s ‘non-activity’ counts were significantly lower

than those of juveniles (χ2=8.748, df=1, p≤0.01), and adolescents (χ2=8.314, df=1, p

≤0.01); while their ‘activity’ counts were significantly higher than those of juveniles

(χ2=6.215, df=1, p≤0.05) and adolescents (χ2=5.875, df=1, p≤0.05), as well as their

‘social’ activity counts (higher than juveniles, χ2=33.018, df=1, p≤0.001; higher than

adolescents χ2=31.221, df=1, p≤0.001). No significance was found for counts

between juveniles and adolescents for ‘non-activity’ (χ2=0.006, df=1, p=0.940),

‘activity’ (χ2=0.005, df=1, p=0.945) or ‘social’ activities (χ2=0.029, df=1, p=0.866).

No significant different was found between counts of ‘feed/forage’ between the age-

classes (χ2=3.817, df=2, p=1.48), although for both juveniles and adolescents,

‘feed/forage’ was observed more, while for infants ‘feed/forage’ was the second most

observed activity.

Significant differences were observed between age-classes for ‘movement’

(χ2=12.000, df=2, p≤0.01). Infants’ ‘movement’ was counted more than juveniles’,

although no significant difference was found (χ2=2.118, df=1, p=0.146). Adolescents’

‘movement’ counts were lower than those of infants (χ2=12.050, df=1, p≤0.01) and

juveniles (χ2=4.128, df=1, p≤0.05).


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Table 10. Activity budgets overall and per age-class. ‘Active’ represents the sum of social and non-social activities, and non-active represents rest.

Active Non active

Proportional

count Mean

percent Proportional

count Mean

percent Infants 489.91 63.3 284.1 36.7 Juveniles 415.26 53.65 358.76 46.35 Adolescents 417.17 53.9 356.82 46.1 Total 1322.34 56.92 999.68 43.05

Table 11. ‘Active’ activity budgets overall and per age-class.

Non social Feed / forage Movement Other Social

Proportional

count Mean


count Mean


count Mean


count Mean

percent Infants 122.72 15.86 148.13 19.14 63.88 8.25 155.18 20.05 Juveniles 151.51 19.57 123.62 15.97 71.1 9.19 69.03 8.92 Adolescents 150.56 19.45 93.6 12.09 101.86 13.16 71.15 9.19 Total 424.78 18.29 365.35 15.73 236.83 10.2 295.36 12.72


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Activity budgets within and between individuals (Tables 12 and 13):

Clandestine, Pattex, Youbi and Mila presented higher ‘active’ than ‘non-active’

levels. Bianieffe’s ‘active’ counts were higher than her ‘non-active’ counts, but not

much different, while Dolly presented more ‘non-activity’ counts than ‘active’ counts.

The lowest counts for ‘movement’ were presented by Clandestine and Dolly. Dolly

also presented the lowest counts for ‘social’ and ‘non-social’ activity. On the other

hand, Mila presented the lowest counts of ‘non-active’ and highest counts of both

‘active’ and ‘social’ activity. Bianieffe presented the highest counts of ‘feed/forage’,

while Youbi the lowest. Pattex presented the highest counts for ‘movement’.

Overall, ‘social play’ was the most commonly counted ‘social’ activity (Bianieffe

94.44%; Clandestine 82.35%; Dolly 76%; Pattex 92.86%; Youbi 93.15%; Mila

97.5%). ‘Grooming’ accounted for very low counts among ‘social’ activities (Bianieffe:

2.78% groom; Clandestine: 2.94% mutual groom, 2.94% being groomed; Dolly: 4%

groom, 12% being groomed; Pattex 4.76% groom, 2.38% being groomed; Youbi

1.37% mutual groom; 4.11% being groomed). ‘Hug’ was counted only for certain

individuals (Dolly 4%; Youbi 1.37%; Mila 2.5%).

For ‘non-social’ activities, 2 counts of ‘urofragy’ were taken for Clandestine, and 16

counts of ‘stereotypical behaviour’ for Dolly. Dolly was also observed to build nests

the least out of all other individuals (1/33, 3.03% of all nest building counts). Pattex

(10 out of 33 = 30.3% of nest building counts) and Bianieffe (9/33, 27.27% of nest

building observations) were observed to build more nests than all other individuals.


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Table 12. Activity budgets by individual. ‘Active’ represents the sum of social and non-social activities, and non-active represents rest.

Active Non active

Proportional

count Mean


count Mean

percent Bianieffe 199.17 51.47 187.82 48.53 Clandestine 218 56.33 169 43.67 Dolly 171.32 44.27 215.69 55.73 Pattex 243.94 63.03 143.07 36.97 Youbi 237.29 61.32 149.71 38.68 Mila 252.62 65.28 134.39 34.73

Table 13. ‘Active’ activity budgets by individual

Non social Feed / forage Movement Other Social

Proportional

count Mean


count Mean


count Mean


count Mean

percent Bianieffe 82.56 21.33 51.6 13.33 27.86 7.2 37.15 9.6 Clandestine 68 17.57 42 10.85 74 19.12 34 8.79 Doly 76.37 19.73 40.25 10.4 28.9 7.47 25.8 6.67 Pattex 75.14 19.41 83.37 21.54 42.2 10.9 43.23 11.17 Youbi 58.05 15 77.4 20 27.5 7.11 74.34 19.21 Mila 64.67 16.71 70.73 18.28 36.38 9.4 80.84 20.89

Pre-release monitoring of play behaviour and relationships in a group of orphaned chimpanzees (Pan troglodytes troglodytes) at the H.E.L.P. Congo sanctuary and release site

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