Ellis 2002

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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.

BETH ANN

WildlifeForensicservices,.O. Box 142613, Irving, TX 75014-2613 U.S.A.

J^MESK. F^CK•ER590 Davidson Road, Bow, WA 98232 U.S.A.

BRL•N A. M•LLS^P

Fish and WildlifeConservation ommission,20 S. Me•dian Street, allahassee,L 32399 U.S.A.

K•YWoRD$: Peregrinealcon; alco peregrinus;Argentina;

Chile;, allidFalcon; rey.

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-

E-mail address: [email protected] dcellis@theriver. corn

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.

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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

Pachyptila elcheri Slender-billed Prion

Pelecanoididae Pelecanoidesagellani Magellanic Diving-Petrel

Pelecanoidesp. 3

Ardeidae Nycticorax ycticorax Black-crownedNight-Heron

Threskiornithidae Theristicus caudatus Buff-necked Ibis 7 *4

Anatidae CMoephagaicta Upland Goose

A nas sp.

Anas lavirostris Speckled Teal 2

Anasplatalea Red Shoveler

Falconidae Falcosparverius American Kestrel

Phasianidae Gallusgallusdomesticus Domestic Chicken

Rallidae Fulica leucoptera White-winged Coot

Charadriidae Vanellus hilensis Southern Lapwing 1

Charadriusalklandicus Two-banded PloverCharadrius modestus Rufous-chested Plover

Oreopholusuficollis Tawny-throatedDotterel 1

Scolopacidae Limosahaemastica Hudsonian Godwit

Gallinago tricklandii Fuegian Snipe

Thlnocoridae Thinocorus rbignyianus Gray-breastedSeedsnipe 2

Thinocorusumicovorus Least Seedsnipe 17

Larldae Sternasp. 2Sterna hirundinacea South American Tern

Columbidae Zenaida auriculata Eared Dove

Metriopeliamelanoptera Black-wingedGround-doveColumba livia Rock Dove +

Pslttacidae Cyanoliseusatagonus BurrowingParakcetEnicognathusferrugineus Austral Parakeet 4

Caprimulgidae Caprimulgusongirostris Band-wingedNightjarFurnariidae Geositta cunicularia Common Miner

Upucerthia umetaria Scale-throatedEarthcreeper

Eremobiushoenicurus Band-tailed Earthcreeper

Cinclodesitscus Bar-wingedCin clodes 1

Cinclodesatagonicus Dark-bellied Cinclodes 4

Leptasthenuraegithaloides Plain-mantled Tit-Spinetail

Tyrannidac Neoxolmisufiventris Chocolate-ventedTyrant 1

Muscisaxicola acloviana Dark-faced Ground-Tyrant

Lessoniaufa Patagonian Negrito

Hirundinidae 7achycineta eyeni Chilean Swallow

Notiochelidonyanoleuca Blue-and-white Swallow

Troglodytidae Troglodytesusculus Tropical House-WrenSturnidae Mimuspatagonicus PatagonianMockingbirdMuscicapidac Turdusfalcklandii Austral Thrush 2

+

+

+

+

+

+

+

+

+

+

+

1

1

1'

1

1

2

1'

1

3&2'

7&1'

1

4

5

16

1

2

1

1

3

2

2

1

2

1

1

2

2

1

2

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DECEMBER 2002 SHORT COMMUNICATIONS 317

Table 1. Continued.

PERES AND

MCNUTT PERES THIS

FAMILY SCIENTIFIC NAME COMMON NAME 1981 s 1985 s STUDY 3

Montacillidae

Fringillidae

Anthuscorrendera Correndera Pipit 1

Agelaius hilius Yellow-wingedBlackbird 1Sturnellamilitaris Pampas Meadowlark +

Sturnellaoyca Long-tailed Meadowlark 1Molothrusbonariensis Shiny Cowbird 1

Phyrgilus ayi Grey-hooded Sierra-Finch 1

Phyrgilusfruticeti Mourning Sierra-Finch 3

Phrygilus nicolor PlumbeousSierra-Finch 1

Melanoderamelanodera Canary-winged inch 1Diuca diuca Common Diuca-Finch 3

Sicalis luteola Grassland Yellow-Finch 3Carduelis barbata Black-chinned Siskin 1

Unknown 8 0 9

Total individuals 53+ unknown 102

Total identified

individuals 45 unknown

Minimum no. species 13 17

93

42

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-

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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

presasde 11 nidos, ariade 93 presas dentificadas epre-

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

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, 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

Peregrine Fund, Boise, ID U.S.A.

BIELEFELDT,., R.N. ROSENFIELD,ND .M. PAPP. 992. Un-

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C^WKE[L,E.M. ANDJ.E. HAMraTON.1961. The birds ofthe Falkland Islands. Ibis 103:1-27.

ELLIS, D.H. AND R.L. GLINS•a. 1980. Some unusual re-

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--AND C. PERES. 983. The Pallid Falcon Falcokrey-

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kreyenborgi:ore pieces or the puzzle. RaptorRes.15.42-45.

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Received7 January 2001; accepted 10 July 2002

Ellis 2002

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