j. Raptor Res. 36(4):315-319 ¸ 2002 The Raptor Research Foundation, Inc. PREY OF THE PEREGRINE FALCON (FALCO EREGRINUS AS57Ni) N SOUTHERN ARGENTINA AND CHILE USGS Patuxent WildliJb esearch ente•; C 1 Box 4420, Oracle, AZ 85623 U.S.A. BETH ANN Wildlife Forensics ervices, .O. Box 142613, Irving, TX 75014-2613 U.S.A. J^MES K. F^CK•ER 590 Davidson Road, Bow, WA 98232 U.S.A. BRL•N A. M•LLS^P Fish and Wildlife Conservationommission, 20 S. Me•dian Street, allahassee, L 32399 U.S.A. K•YWoRD$: Peregrine alcon; alco peregrinus; Argentina; Chile;, allid Falcon; rey. The Peregrine Falcon (Falco peregrinus assini) n Pata- gonia attracted wide in terest two decades ago (Anderson and Ellis 1981, McNutt 1984) when there was a focus on etermining the taxonomic position of the Pallid Falcon falcon; formerly named Falco kreyenborgi). n 1981, how- ever, the pallid falcon was confirmed to be a pale color morph of the peregrine (Ellis et al. 1981, Ellis and Peres 1983), and since that time, little work has been conduct- ed on this color morph. Continent-wideresearch has continued and has yielded a fair understanding of the breeding distribution of the Peregrine Falcon in South America (Anderson et al. 1988, McNutt et al. 1988, Rise- brough et al. 1990). Also, two pr eliminary fo od habits studies on the peregrine have been completed in Pata- gonia (McNutt 1981, Peres and Peres 1985). Together those papers provided a list of 23 species observedas prey, and McNutt (1981) listed another eight species seen pursued (but not captured) by peregrines. The purpose of this paper is to assemble all that has been published on peregrine food habits for Patagonia and Tierra del Fuego and to add to that list from our 1980 and 1981 expeditions. METItODS In November-December of 1980 and 1981, we traveled by motor vehicle searching for eyries n Chubut, Santa Cruz, and Rio Negro provinces of Argentina and in Ma- gallanes, Chile. Although we accessed 16 eyries, some were empty (prey remains sometimes scatter in the wind), so our totals included prey from only 11 eyries. We accessed yries (normally by rope) and recovered re- cent prey (feathers, feet, and bones with tendons at- E-mail address: [email protected]r dcellis@ theriver. corn tached) but discarded those bones that were so bleached that they may be attributed to former occupants of the eyrie. Most of the prey were identi fied from whole feath- ers. No pellets were used in this anaylsis. We included some feathers f?om the base of the eyrie cliff g, but ex- cluded those that were likely molted by other occupants of the cliff. For example, several of our eyries were in old Black-faced lbrmerly buff-necked) Ibis (Theristicus au- datus) nests within active ibis colonies. Although •b•s feathers were frequently found near these eyries and even though we occasionally observed peregrines pursu- ing ibis, we viewed these attacks near eyries as displace- ment activities. Only once did we include an ibis as prey and this was after findi ng four fresh •athers within an eyrie which was neither beneath an ibis roost nor near an ibis nest. McNutt (1981) observed peregrines kilhng nestling ibis. No food habits study based on prey remains is without bias (Marti 1987, Bielefeldt et al. 1992). For peregrin es, bias derives rom the fact that many prey individuals are missed because prey are normally plucked belbre arrival at the eyrie and many defieshed carcasses re removed by the adults and deposited elsewhere. Also, several cast- ings sometimes epresent a single prey item. Common prey are normally under represented n peregrine prey tallies, ncluding our sample, because of the difficulty of totaling individuals. Our method was to derive a mira- mum count from feet, bills, remiges, and rectrices. For example, a sample of 300 feathers and assorted other remains from one species, and probably representing dozens of individuals, may yield a much smaller mm•- mum count. Conversely, are prey are likely to be over estimated in most studies ncluding this one, because a single feather, b ill, or foot can document prey that was accrued only once. Prey were placed n plastic bags and air dried by open - ing the bags in a windless situation on sunlit days and fumigated pri or to identification at the U.S. National Mu- seum (USNM: Smithsonian Institute). At USNM, we as- sembled a synoptic series nclud ing all known and most of the likely prey species. Because USNM does not have examples for all plumages of all Patagonian birds, we could n ot determine species on nine individuals. 315
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
8/8/2019 Ellis 2002
http://slidepdf.com/reader/full/ellis-2002 1/5
j. RaptorRes.36(4):315-319
¸ 2002 The Raptor ResearchFoundation, Inc.
PREYOF THE PEREGRINEFALCON (FALCO EREGRINUSAS57Ni)NSOUTHERN ARGENTINA AND CHILE
DAVID H. ELLIS 1
USGSPatuxentWildliJb esearch ente•; C 1 Box 4420, Oracle,AZ 85623 U.S.A.
The Peregrine Falcon (Falcoperegrinus assini) n Pata-
gonia attracted wide interest two decadesago (Anderson
and Ellis 1981, McNutt 1984) when there was a focus on
determining the taxonomic position of the Pallid Falcon
(also called Kleinschmidt's alcon and Tierra del Fuego
falcon; formerly named Falcokreyenborgi).n 1981, how-
ever, the pallid falcon was confirmed to be a pale color
morph of the peregrine (Ellis et al. 1981, Ellis and Peres1983), and since that time, little work has been conduct-
ed on this color morph. Continent-wide research hascontinued and has yielded a fair understanding of the
breeding distribution of the Peregrine Falcon in SouthAmerica (Anderson et al. 1988, McNutt et al. 1988, Rise-
brough et al. 1990). Also, two preliminary food habits
studies on the peregrine have been completed in Pata-gonia (McNutt 1981, Peres and Peres 1985). Together
those papers provided a list of 23 speciesobserved asprey, and McNutt (1981) listed another eight species
seen pursued (but not captured) by peregrines.
The purpose of this paper is to assembleall that hasbeen published on peregrine food habits for Patagoniaand Tierra del Fuego and to add to that list from our
1980 and 1981 expeditions.
METItODS
In November-December of 1980 and 1981, we traveled
by motor vehicle searching for eyries n Chubut, SantaCruz, and Rio Negro provincesof Argentina and in Ma-gallanes, Chile. Although we accessed16 eyries, somewere empty (prey remains sometimes scatter in thewind), so our totals included prey from only 11 eyries.We accessed yries (normally by rope) and recovered re-
cent prey (feathers, feet, and bones with tendons at-
tached) but discarded those bones that were so bleached
that they may be attributed to former occupantsof theeyrie. Most of the prey were identified from whole feath-ers. No pellets were used in this anaylsis.We includedsome feathers f?om the base of the eyrie cliffg, but ex-cluded those that were likely molted by other occupantsof the cliff. For example, severalof our eyrieswere in oldBlack-faced lbrmerly buff-necked) Ibis (Theristicus au-datus) nests within active ibis colonies. Although •b•sfeathers were frequently found near these eyries andeven though we occasionallyobservedperegrines pursu-
ing ibis, we viewed these attacksnear eyries as displace-ment activities.Only once did we include an ibis as preyand this was after finding four fresh •athers within aneyrie which was neither beneath an ibis roost nor nearan ibis nest. McNutt (1981) observed peregrines kilhngnestling ibis.
No food habits studybased on prey remains is withoutbias (Marti 1987, Bielefeldt et al. 1992). For peregrines,bias derives rom the fact that many prey individualsaremissedbecauseprey are normally plucked belbre arrivalat the eyrie and many defieshed carcasses re removedby the adults and deposited elsewhere.Also, severalcast-ings sometimes epresent a single prey item. Common
prey are normally under represented n peregrine preytallies, ncluding our sample,becauseof the difficulty oftotaling individuals. Our method was to derive a mira-mum count from feet, bills, remiges, and rectrices. Forexample, a sample of 300 feathers and assorted otherremains from one species, and probably representingdozens of individuals, may yield a much smaller mm•-mum count. Conversely, are prey are likely to be overestimated in most studies ncluding this one, because asingle feather, bill, or foot can document prey that wasaccrued only once.
Prey were placed n plasticbagsand air dried by open-ing the bags in a windless situation on sunlit days andfumigated prior to identification at the U.S. National Mu-
seum (USNM: Smithsonian Institute). At USNM, we as-sembled a synopticseries ncluding all known and mostof the likely prey species.BecauseUSNM does not haveexamples for all plumages of all Patagonian birds, wecould not determine specieson nine individuals.
315
8/8/2019 Ellis 2002
http://slidepdf.com/reader/full/ellis-2002 2/5
316 SHORT COMMUNICATIONS VOL. 36, NO. 4
Table 1. Avian prey of the Peregrine Falcon in southern Patagoniaand Tierra del Fuego) 2 Numbers refer tominimum number of items represented n remains.A plus (+) indicates hat a taxa wasdocumented, but the number
of items was not reported. Nomenclature follows Sibley and Monroe (1990).
PERES AND
MCNUTT PERES THIS
FAMILY SCIENTIFIC NAME COMMON NAME 1981 s 19853 STUDY 3
Rheidae Rheapennata Lesser Rhea
Tlnamidae Eudromiaelegans Elegant Crested-Tinamou
Podicipedidae Podiceps ajor Great GrebeProcellariidae Halobaena caerulea Blue Petrel
Not listed s a Kelp Gull (Larus dominicanus)bserved s prey of a uvenile Pallid Falcon on 10 March 1979 (Ellis and Glinski 1980)
Nonavianprey nclude only a lizard (Liolaemusp.) m•d a smallrodent.An asterisk *) in thesecolumns dentifiesprey that had not achieved dult size.it is not certain that all 7 ibis were nestlingswhen taken.
We identified feathers by placing materials rom oneeyrie in a shallow white box and from prior experiencesorted the feathers nto piles tentativelyassigned o a like-ly taxon. A representative eather wasgraspedby forcepsthen compared to specimensof likely donor species.Once a good match for size, color, and pattern wasfound, the pile of featherswassorted to remove any thatdid not represent his species nd morph. Then the pro-cesswascommencedanew.After one of us completedan•dentification or featherswithout unique color patterns(and most passefine primaries do not have bold colorpatterns), a second person evaluated the feathers and
confirmed or rejected the identification. The most diffi-cult materials often required an evaluation extending anhour or more before a certain match was found. Occa-
stunally,a feather had to be washed and blow dried be-fore comparisons ould be made. All identified materialswere baggedseparately nd archived.
In comparing feathers, it was often necessary o fanthe wing or tail on the museum skin; to do so withouttearing the skin required holding the appendage inalignment with the body while deflecting the tip of thefeather with forceps.To aid in this process,we preparedflat skinswith tail and one wing fanned for about 50 spe-cieswhile in Argentina. For some other species,we mere-ly placedwings, ail, feet, beak, and feathers epresentingall body areas n a plasticbag. All specimenswere deliv-ered to the Argentine Museum of Natural Sciences,BuenosAires, Argentina, where the most valuablewereretained. The remainder were released for export andshipped to the U.S.A.
RESULTS
From this and the previous wo studies McNutt 1981,Peres and Peres 1985), we have documented a fair variety
of the prey taken by the peregrine in Patagonia.McNutt(1981) identified 13 prey speciesand two other genera.Peres and Peres (1985) noted 17 species,of which 10
were new (i.e., not previouslynoted by McNutt [1981])
The list from our study (Table 1) includes42 speciesofwhich 32 were not previously ecorded. In summary,atleast 55 prey species n 26 families are known to be taken
by peregrines in Patagonia. To this can be added theKelp Gull (Larus dominicanus)ecorded as prey of a ju-venile Pallid Falcon seen on 10 March 1979 (Ellis and
Glinski 1980).
DISCUSSION
Our list doesnot represent he full range of prey taken
by the Peregrine Falcon in South America, because irstof all, our study included only the southern fifth of the
distribution of this race. Second, other prey speciesareknown to be taken by this falcon in the Falkland Islands
(Cawkell and Hamilton 1961) and in more northerly re-
gions of South America (Hilgert 1988). Third, the lownumbers of individuals aken for common and likely prey
species e.g., only two Austral Thrushes [ Turdusfalcklan-
dii] and one Patagonian Mockingbird [Mimus patagon•-cus] suggest hat much more varietywill come from con-
8/8/2019 Ellis 2002
http://slidepdf.com/reader/full/ellis-2002 4/5
318 SHORT COMMUNICATIONS VOL. 36, NO. 4
unued sampling.The relationship between diversity i.e.,
the number of species etected) and samplesizecan becharacterized as beginning with a 1:1 relationship but
w•th the plot soon leveling off and finally approaching
an upper asymptote (the true maximum in the numberof species aken) only after severalhundred prey are tal-
hed (Heck et al. 1975, Marti 1987). At present, he totalfor all three studies is less than 200 individuals. Further,
the two most commonly taken species n Table I were
representedby only ca. 23 and 16 individuals;betbEe he
upper asymptote s reached, we expect that the numberof individualsof the most commonly-takenprey will ex-ceed 100.
The list of species aken (Table 1) suggestshat the
peregrine is prone to capture some prey on the ground.
The gosling was observedbeing taken on a gravel bar.
Surely, he young rheas,perhaps the tinamou, and likelysome of the other young birds in Table 1 were taken on
the ground. In addition to the avian prey tallied, we also
recorded one lizard (Liolaemus p.) and a sinall mammal
(Rodentia ca. 40 g); both of thesewould likely havebeen
taken on the ground (or kleptoparasitized). n SouthAmerica there is no competing large falcon that hunts
terrestrial prey (i.e., like the Prairie Falcon [F. mexicanus]in North America and the Saker Falcon [F. chefrug] n
Europe and Asia) that may constrain the Peregrine Fal-
con to an aerial foraging niche, so it was to be expected
that the peregrine in Patagoniawould take quarry on the
ground more frequently than do some other races.It is obvious rom the variety of oceanic specieson the
Peres ist (Peresand Peres 1985; Table 1) that their study
emphasizedcoastalareas.Their samplewas also kom an
area where the pallid morph is relatively common (G.
Peres pets. comm.). Their results, in comparison with
our list for inland eyries,where the pallid morph is rare,suggest hat pallid and dark peregrines hunt different
prey. To document this potential difference (i.e., to com-pare the foraging niches of two sympatriccolor morphs)
will surely be an interesting ecological study.Pallid and
normal birds appear very different in the field. Pallid
birds are less conspicuous nd gull-like when seen be-neath gray, overcastskies.We propose that the pallidmorph may have evolvedwhen conditions were right for
a population of pale peregrines o live in isolation rom
the population of normal peregrines further north onmainland South America.
RESUMEN.--A artiEde publicaciones revias, onocelllosmenos de 100 item presa que representan poco menos
de 25 especiesde avespara el halc6n peregrino de laPatagonia (Falcoperegrinus assini).Este estudio, incluye
sentando 42 especiesde aves (32 no reportadas previa-mente), un lagatto, y un mamifero pequefio.Aunque do-
cumentamosuna considerable ariedadde presaspara elhalc6n peregrino en esta egi6n, la frecuencia con la cual
nuevas presas ueron encontradas en cada nido visitado,
sugiere que la diversidadde aves omadas ue mucho mas
grande que la que se describeaquL Estaalta diversidad,en parte, resulta de variedades alidasy de color normal
que ocupan nichos de forrajeo un tanto ditbrentes.
[Traducci6nde C6sarMarquez]
ACKNOWLEDGMENTS
In 1980, the U.S. Air Force funded much of our travel
Our 1981 work was argely funded by the National Geo-graphic Society and an anonymousphilanthropist. Wethank Peter Simpson, manager of EstanciaChacabuco,Rio Negro, Argentina, for logisticalsupport. Phil Angleidentified the lizard. JamieJimenez, ClaytonWhite, andDavid Whiracre reviewedand improved he manuscriptOur thanks to staff at the USNM for allowing space orour synoptic series and patience during the extendedtime devoted o identifyingprey.
LITERATURE CITED
ANDERSON,.M. ANDD.H. ELLIS.1981. FalcokreyenborgJ--a current review. RaptorRes.15:33-41.
, t.L. M_AECHTLE, AND W.G. VASINA. 1988. The
southern breeding limit of the PeregrineFalcon.Pag-es 251-253 in T.J. Cade, J.H. Enderson, C.G. Thelan-
der, and C.M. White lEDS.], Peregrine Falcon popu-lations: their management and recovery. The