Western Kentucky University TopSCHOLAR® Honors College Capstone Experience/esis Projects Honors College at WKU 9-1-2016 e Effects of Drought on Diets of Apex Predators in the South African Lowveld Inferred by Fecal Hair Analysis Shelby Wade Western Kentucky University, [email protected]Follow this and additional works at: hp://digitalcommons.wku.edu/stu_hon_theses Part of the Animal Sciences Commons , Biology Commons , and the Desert Ecology Commons is esis is brought to you for free and open access by TopSCHOLAR®. It has been accepted for inclusion in Honors College Capstone Experience/ esis Projects by an authorized administrator of TopSCHOLAR®. For more information, please contact [email protected]. Recommended Citation Wade, Shelby, "e Effects of Drought on Diets of Apex Predators in the South African Lowveld Inferred by Fecal Hair Analysis" (2016). Honors College Capstone Experience/esis Projects. Paper 669. hp://digitalcommons.wku.edu/stu_hon_theses/669
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Western Kentucky UniversityTopSCHOLAR®Honors College Capstone Experience/ThesisProjects Honors College at WKU
9-1-2016
The Effects of Drought on Diets of Apex Predatorsin the South African Lowveld Inferred by FecalHair AnalysisShelby WadeWestern Kentucky University, [email protected]
Follow this and additional works at: http://digitalcommons.wku.edu/stu_hon_theses
Part of the Animal Sciences Commons, Biology Commons, and the Desert Ecology Commons
This Thesis is brought to you for free and open access by TopSCHOLAR®. It has been accepted for inclusion in Honors College Capstone Experience/Thesis Projects by an authorized administrator of TopSCHOLAR®. For more information, please contact [email protected].
Recommended CitationWade, Shelby, "The Effects of Drought on Diets of Apex Predators in the South African Lowveld Inferred by Fecal Hair Analysis"(2016). Honors College Capstone Experience/Thesis Projects. Paper 669.http://digitalcommons.wku.edu/stu_hon_theses/669
cheetah (Acinonyx jubatus), and wild dog (Lycaon pictus). This study seeks to determine
the diet compositions of two of these apex predators in Balule Nature Reserve, South
Africa: the lion and spotted hyaena.
When hunting, apex predators demonstrate both preference and avoidance of
different species. Selective feeding takes place if a predator consumes equally common
species at different rates (Jacobs 1974). Preferences in diets occur when species are
consumed more than expected based on their relative abundance within an area (Hayward
and Kerley 2005, 2008). When a species is avoided as prey by a predator, the species is
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consumed less than expected based on its relative abundance (Hayward and Kerley 2005,
2008). The diets of apex predators are largely dependent upon the mass of prey, relative
abundance, herd size, and evolutionary adaptations that render a species more or less
susceptible to predators (Hayward and Kerley 2005, Hayward 2006, Rapson and Bernard
2007, Mbizah 2012, Clements et al 2014).
Lions prefer prey species that fall between the range of 92 kg and 632 kg and
avoid species that are < 32 kg and > 632 kg (Clements et al 2014). Both lions and
hyaenas have rich, diverse diets, and have a large dietary overlap (Hayward and Kerley
2008). They both fulfill the upper niche of Africa’s predatory guild, and hyaenas are also
often seen scavenging at lion kill sites (Hayward and Kerley 2008).
Spotted hyaenas prefer prey species between 91 kg and 139 kg and avoid species
< 15 kg. Spotted hyaenas are the only apex predators that do not have a tendency to avoid
prey above a certain mass (Hayward 2006, Clements et al 2014). This is most likely
because hyaenas are often scavengers (Breuer 2005, Hayward 2006, Trinkel 2010,
Clements et al 2014), so prey that they do not kill will also appear in their scat. It could
also be due to their ability to hunt in both group and solo fashions (Breuer 2005,
Hayward 2006).
On average, the Balule Nature Reserve receives 243.4 mm of rainfall between the
months of January and June (Olifants West 2015). In 2014, the area received 317.4 mm
of precipitation within the same amount of time (Olifants West 2015). In the first six
months of 2015, the Balule Nature Reserve experienced a drought, with only 127.6 mm
of rainfall (Olifants West 2015). I compared the diets of lions and spotted hyaenas to a
similar study conducted in 2014 to observe changes in diets of these species within a
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drought period. Prey species have been shown to adjust their behavior by increasing herd
size and vigilance while at waterholes during times of drought, when the risk of
encountering predators is increased (Valiex et al 2009). Therefore, it can be reasonably
hypothesized that the diets of lions and spotted hyaenas will change significantly during
this period of drought, due to changes in behavior of both predators and prey. The results
of this study will also contribute to a long-term study of predator/prey relationships
within the Balule Nature Reserve’s ecosystem.
Study Area
This study took place in Balule Nature Reserve, which is 60 km southwest of
Phalaborwa and 17 km north of Hoedspruit in the Limpopo Province of South Africa
(Olifants 2013). The nature reserve covers 40,000 hectares and makes up the western
boundary of the Greater Kruger National Park, as well as the Association of Private
Nature Reserves (APNR) (Olifants 2013). There are nine administrative units within the
Balule Nature Reserve: Grietjie, Mohlabetsi River (MRNR), Mohlabetsi South, Olifants
East (OREC), Olifants North (ON), Olifants South (OS), Olifants West (OW), Parsons,
and York. Over the past 30 years, Balule has received an average annual rainfall of a little
over 415 mm, which places it within the category of a “semi-arid savannah biome”
(Olifants 2010, page 5; Olifants 2011, page 3). While the landscape and topography
within and between the regions of Balule can fluctuate, Tupsuvihniö (Aristida congesta)
and Curly Leaf (Eragrostis rigidior) have the highest frequency of occurrence among
grass species (Olifants 2014, page 23). Trees dominating the landscape consist of
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Knobthorn (Acacia nigrescens), Raisin Bush (Grewia spp.), Red Bushwillow
(Combretum apiculatum), and Corkwood (Commiphora spp.) (Olifants 2014a).
Figure 1 Map of Balule Nature Reserve and corresponding management districts; image from http://www.olifantsreserve.co.za/documents/Balule%20Management%20Regions.jpg
Methodology
Fecal Collection In 2014, the Balule Nature Reserve adopted a systematic method for
collecting fecal samples, created by Audrey N. Sohikian (Olifants 2014b, page 46-68), in
which 30 plots were chosen within the reserve, and three transects were walked within
each plot. This year, 16 of those plots were sampled, each measuring one square
kilometer. Three one-kilometer transects were walked in every plot. Transects were
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separated by 500 meters. Plots were hiked between June 8, 2015, and August 6, 2015.
Anywhere from two to five observers walked along the different transects, scanning the
ground for predator feces. Apex predator feces are easily distinguished from other scat by
their size, white appearance, and presence of hair. When scat was found, it was placed in
a plastic sealable bag, labeled, and the GPS coordinates were recorded. Scats were
identified with the assistance of field guides, as well as a scat identification book (Murray
2011).
Figure 2 Plots sampled in 2014 (Olifants 2014b)
Figure 3 Plots sampled in 2015
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Fecal Analysis To analyze all fecal samples without bias, it was necessary to develop a
sampling method to randomly select hairs for identification. Similar to Eagle and Pelton
(1983), Hellgren (1993), Marker et al (2003), Ott et al (2006), and Martins et al (2011), a
grid was created on a wooden board with 24 columns and 12 rows, totaling 288 cells with
an area of 9 cm2 each. Fecal samples were crumbled by hand, and evenly spread out
along to grid. Using a random number generator (random.org), five cells were chosen,
and all hairs were collected from these cells.
Figure 4 Grid used for subsampling method
After collecting hairs from the grid, they were distributed evenly in a petri dish
with 25 labeled points on the bottom. The hair closest to each point was chosen for
identification. If the sample contained fewer than 25 hairs, all hairs were identified. Hairs
were placed in distilled water for one hour and then moved to 91% isopropyl alcohol for
a few minutes for cleaning (Sahajpal and Goyal 2009). After completing 24 samples, it
was determined that no more than 18 hairs were necessary for identifying all species
within a sample.
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Figure 5 Petri dish with 18 points, used for hair selection
After cleaning, hairs were placed on a microscope slide with a drop of distilled
water, and a cover slip was placed on top. They were viewed under a WILD M20-90715
microscope to observe the medulla and cortex. Cuticular scale imprints were made for
each hair by spreading a thin layer of Henkel NB Multi-Purpose Cement (part #1589347)
on a microscope slide and pressing the unknown hair overtop. The glue was allowed to
dry, hairs were pulled off using a pair of thin-point tweezers, and the scale impressions
were viewed under the microscope. Medullary characteristics and scale patterns were
compared to reference materials (Keogh 1983, Backwell et al 2009, Seiler 2010, Taru and
Backwell 2013, Taru and Backwell 2014). A catalog of reference hairs from Limpopo
Taxidermy, the Louisville Zoo (Kentucky, USA), and the Thomas M. Baker Collection
(Kentucky, USA) were also used. These microscopic characteristics, along with some
macroscopic characteristics, were used to identify hairs to the species level when
possible. If more than one item from the same species was found in a scat sample, it was
considered to be from the same individual animal.
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Species Studied Only hairs from game species in the Balule Nature Reserve were
identified. Classifications follow Wilson and Reeder (2005):
Scientific Name Common Name
Aepyceros melampus—Lichtenstein 1812 impala
Connochaetes taurinus—Burchell 1824 blue wildebeest
Kobus ellipsiprymnus—Ogilby 1833 waterbuck
Oreotragus oreotragus—Zimmerman 1783 klipspringer
Raphicerus campestris—Thunberg 1811 steenbok
Sylvicapra grimmia—Linnaeus 1758 bush duiker
Syncerus caffer—Sparrman 1779 African buffalo
Tragelaphus angasii—Angas 1849 nyala
Tragelaphus scriptus—Pallas 1766 bushbuck
Tragelaphus strepsiceros—Pallas 1766 greater kudu
Giraffa camelopardalis—Linnaeus 1758 giraffe
Phacochoerus africanus—Gmelin 1788 warthog
Panthera leo—Linnaeus 1758 lion
Panthera pardus—Linnaeus 1758 leopard
Crocuta crocuta—Erxleben 1777 spotted hyaena
Equus burchellii—Gray 1824 Burchell’s zebra
Table 1 Species whose hair was gathered for reference and characterized
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Statistical Analysis Several different tests were used to analyze the diet compositions
of both apex predators. First, the proportions for all species found in scat samples were
determined by dividing the number of occurrences of one species found in all samples by
the total occurrences of all species. These proportions were compared with the species
availability determined by aerial game counts, as well as with the results from the study
completed in 2014 (Olifants 2014b, page 46-68), using the Jacob’s Index (Jacobs 1974)
and the g-test goodness-of-fit (Rohlf and Sokal 1981, Sokal and Rohlf 1981).
The Jacob’s Index was applied to each species found in scat samples to determine
selected and non-selected prey species of both apex predators. The Jacob’s Index is as
follows:
𝐷 =𝑟 − 𝑝
𝑟 + 𝑝 − 2𝑟𝑝
where r is equal to the proportion of a species found in scat samples, and p is equal to the
proportion of a species found in game counts (Jacobs 1974). D values range from -1 to
+1, with values less than zero indicating a species was consumed less than expected
based on its relative abundance, zero indicating prey was consumed equal to its relative
abundance, and values greater than zero indicating prey was consumed more than
expected based on its relative abundance.
The g-tests determined whether there were any significant differences in the total
diet composition of either predator when comparing it to both the game counts and the
results from 2014. The formula is as follows:
𝑔 = 2∑𝑂𝑖 × ln𝑂𝑖𝐸𝑖
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where Oi represents the number of a certain prey species observed in all samples, and Ei
represents the number of times that same species would be expected to appear in the
same number of samples based on the proportions from aerial game counts or 2014’s
observations (Rohlf and Sokal 1981, Sokal and Rohlf 1981). This test was conducted
twice for each predator—once to compare with the expected results coming from aerial
game counts, and once to compare with the expected results coming from 2014’s results.
If any species was not detected in the fecal samples, they were omitted from the
g-test. Therefore, when comparing the proportions of prey species found in lion scat in
2014 to proportions of prey species found in lion scat in 2015, steenbok, warthog, and
wildebeest were omitted from the g-test equation. Wildebeest was not detected in any of
the fecal samples found in 2014, and steenbok and warthog were not detected in any of
the fecal samples tested in 2015. Because steenbok and warthog were not detected in any
of the fecal samples in 2015, they were also omitted from the g-test when comparing the
proportions of prey species found in lion scat in 2015 to the proportions of prey species
found during aerial game counts. Nyala was not detected in hyaena scat in 2014, so it was
omitted from the g-test when comparing proportions of prey species found in hyaena scat
in 2014 to the proportions of prey species found in hyaena scat in 2015.
Results
In total, 87 fecal samples were collected between June 8, 2015, and August 6,
2015. Of the 87 samples collected, 68 scats contained hair that was able to be identified.
Hairs in exceptionally old, deteriorated samples were damaged past the point of
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identification. Therefore, it should be noted that it is not of use to collect scat samples
which have been exposed to much weathering and degradation (Breuer 2005, Yihune and
Bekele 2014).
Most scat samples were collected from the regions of Olifants South, Olifants
West, Jejane, and York. No scat samples were found within transects in the regions of
Parsons, Olifants North, and Greitjie. While some scat samples were spotted in these
plots, they were not located within transects, and thus could not be collected. It would be
wise to allow opportunistic scat collection while walking between different transects, to
allow more opportunity for scat collection.
Figure 6 Distribution of all 87 predator scat samples collected in 2015
Of the 68 scat samples that could be identified, 34 scat samples were identified as
hyaena scat and 34 were identified as lion scat. Tables 2 and 3 display the number of
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scats containing hairs of each prey species consumed by each predator, and in which
regions the fecal samples containing those prey hairs were located.
Lion prey consumption across all regions of Balule Nature Reserve
Jejane MRNR OS OW OREC York
bushbuck 1 0 0 0 0 0
duiker 0 0 1 0 0 2
giraffe 2 0 1 0 0 0
impala 4 2 3 1 0 11
kudu 0 1 0 1 1 2
nyala 1 1 1 0 0 1
steenbok 0 0 0 0 0 1
warthog 0 0 0 0 0 0
waterbuck 0 0 0 0 0 1
wildebeest 1 0 0 0 0 0
zebra 0 0 0 0 0 8
Table 2 Number of scats containing hairs of each prey species by region consumed by
lion
Hyaena prey consumption across all regions of Balule Nature Reserve
Jejane MRNR OS OW OREC York
bushbuck 0 3 0 0 0 0
duiker 1 1 0 0 0 0
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giraffe 0 2 0 0 0 0
impala 4 8 0 2 0 6
kudu 1 2 0 0 0 3
nyala 0 1 1 0 0 2
steenbok 0 0 1 0 0 0
warthog 0 0 1 0 0 0
waterbuck 3 0 0 1 0 3
wildebeest 0 1 0 2 0 0
zebra 1 0 0 0 0 9
Table 3 Number of scats containing hairs of each prey species by region consumed by
hyaena
When comparing proportions of species consumed found in lion scat, impala and
zebra made up the greatest proportions. Steenbok and warthog were totally absent. These
proportions were compared with the proportions of species found during aerial game
counts, as well as the results found in the 2014 study.
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Figure 7 Bar graph comparing proportions of species found in lion fecal samples in 2014,
2015, and aerial game counts
Proportions of prey species found in hyaena fecal samples were also compared to
proportions found during aerial game counts and results from the study conducted in
2014. Similar to the lion, impala and zebra also made up the largest proportion of species
found in hyaena diets for 2015.
Figure 8 Bar graph comparing proportions of species found in hyaena fecal samples in
2014, 2015, and in aerial game counts
0
0.5
1
1 2 3 4 5 6 7 8 9 10 11
Pro
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f Sp
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Proportions of prey species found in lion fecal samples in 2014 and 2015 and in aerial game counts
Proportion of species found in lion fecal samples in 2014
Proportion of species found in lion fecal samples in 2015
Proportion of species found during aerial game counts
0
0.2
0.4
0.6
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Pro
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Proportions of prey species found in hyaena fecal samples in 2014 and 2015 and in aerial game counts
Proportion of species found in hyaena fecal samples in 2014
Proportion of species found in hyaena fecal samples in 2015
Proportion of species found during aerial game counts
47
These proportions were used when calculating the Jacob’s Index for each species
consumed by each predator. The Jacob’s Index is shown here for both 2014 and 2015 for
an easy comparison between studies.
Figure 9 Jacob's Index values for all species in lion and hyaena diets in 2014
Figure 10 Jacob's Index values for all species in lion and hyaena diets in 2015
-1
-0.5
0
0.5
1
Jaco
b's
Ind
ex V
alu
es f
or
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Spec
ies
Axis Title
Comparison of Jacob's Index Values Between Lion and Hyaena in 2014
Lion Hyaena
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
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Jaco
b's
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or
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ies
Comparison of Jacob's Index Values Between Lion and Hyaena in 2015
Lion Hyaena
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These proportions were also used to calculate g-values to compare proportions of
different prey species in the scat of each predator species to both aerial game counts and
the results from the 2014 study. The results are shown in Tables 4 and 5.