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112 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 118, No. 1, March 2006 LITERATURE CITED Lowen, J. C., L. Bartrina, T. M. Brooks, R. P. Clay, Anonymous. 2002. A new population of the White- abinrdd sJ.urTvoebyisasa.nd19c9o6n.sePrrvoajteicotnYprAioCriUtTieIsNinGeAast’e9r5:n winged Nightjar. World Birdwatch 24:5. Paraguay. Cotinga 5:14-19. Brace, R. C. 2000. The avifauna ofthe Beni Biolog- Marris, E. 2005. The forgotten ecosystem. Nature ical Station: records to 1999. Estacion Biologica 437:943-944. Bracdee,lRB.enCi.,, BJ.olHivoiran.buckle, and J. W. Pearce-Hig- Parke1r9,96T..EAc.o,lIolgl,icDa.lFa.nSdtodtizs,traibnudtiJo.naWl.dFaittazbpaastersicfko.r gSitnast.ion1,99B7o.liTvihae. aBviirfdauCnoansoefrvtahetioBneniIntBeironlaotgiiocnaall Neotropical birds. Pages 118-407 in Neotropical 7:117-159. birds: ecology and conservation (D. F. Stotz,J. W. ClayB,urRf.ieRl,d,D.E.R.Z.CEaspqpueirv,elJ.,MR.azFaarrinBaa,rnCe.ttP.,KIe.nJ-. Fitist)z.paUtnriivcekr,siT.tyA.ofPaCrhkeirc,agIIoI,Parensds,D.ChKi.caMgoos,koIlvli-- nois. nedy, M. Perrens,andR. G. Pople. 1998. White- Pople, R. G. 2003. The ecology and conservation of wingedNightjars Caprimulguscandicansandcer- the White-winged Nightjar Caprimulgus candi- rado conservation: the key findings of Project Aguara Nu 1997. Cotinga 9:52-56. cans. Ph.D. dissertation,UniversityofCambridge, United Kingdom. Cleere, N. 1999. Family Caprimulgidae (nightjars). Pages 302-386 in Handbook of the birds of the Pople, R. G. 2004. White-winged NightjarEleothrep- world, vol. 5: barn-owls to hummingbirds (J. del tus candicans. In Threatened birds of the world Hoyo, A. Elliott, and J. Sargatal, Eds.). Lynx Ed- 2004. CD-ROM. BirdLife International, Cam- icions, Barcelona, Spain. bridge, United Kingdom. Cleere, N. 2002. A review ofthe taxonomy and sys- Rodrigues, F. H. G., A. Hass, O. J. Marini-Filho, M. tematics of the Sickle-winged and White-winged M. GuimarAes, and M. A. Bagno. 1999. A new nightjars (Caprimulgidae). The Bulletin of the record of White-winged Nightjar Caprimulgus British Ornithologists’ Club 122:168-179. candicans in Emas National Park, Goias, Brazil. Davis, S. E. and E. Flores. 1994. First record of Cotinga 11:83-85. White-winged Nightjar Caprimulgus candicans Sclater, P. L. 1866. Additional notes on the Capri- for Bolivia. The Bulletin of the British Ornithol- mulgidae. Proceedings of the Zoological Society ogists’ Club 114:127-128. ofLondon 1866:581-590. The Wilson Journal ofOrnithology 1 18(1):112-113, 2006 Predation of Eared Grebe by Great Blue Heron James W. Rivers' 2 and Michael J. Kuehn1 — ABSTRACT. Great Blue Herons (Ardea herodias) On the morning of 14 November 2004, we typically prey upon fish and other aquatic organisms, witnessed an adult Great Blue Heron {Ardea Wltaiense)md.pottTbhhsteeoeyrchovoecercndaossnauimowGenaraeslaalntuynEBatalabrukleeeedstHGmoerarelsolbwneamla(altPomtowamdciaktc,lheeskpisglalr,nnedibagenr,bidicraodanlstd-.- haFenlraoEcdoairaeLsda)kGaerttea(bc3ek5,°{k0Pi0oll'd,iNac,nepds1a2tn0it°germ3i0pc'tolWtloi)sc)oianntsOuSsmaoen it abandoned the carcass after approximately 30 min. Luis Obispo County, California. The incident An examination of the carcass showed that the grebe occurred shortly after the heron landed near lacked obvious physical deformities. Our observation, the grebe and began foraging in shallow (~30 coupled with a similarone nearby, indicates that Great cm deep) water. At approximately 11:25 PST, Blue Herons attack and kill birds larger than reported the heron caught the grebe with a stabbing previously. Received 11 January 2005, accepted 19 September 2005. motion as the grebe swam underwater. The heron then proceeded to subdue the grebe by grasping its neck, shaking it, and submerging Uni1vD.epotf,CoalfiEfocronlioag,y,SaEnvtoaluBtairobna,raa,ndCAMar93i1n0e6.BioUlSoAg.y, titheingtrerembiettaenptpleya.reAdftteor baeppdreoaxdi.maAtteltyhis15pomiinnt,, 2Corresponding author; e-mail: the heron briefly released the grebe to deliver [email protected] several sharp blows to its head and chest area. SHORT COMMUNICATIONS 13 1 The heron attempted several times to swal- Butler pers. comm.). Thus, it is possible that low the grebe, but it had difficulty maneuver- the herons may have targeted the grebes as ing the grebe into its mouth. During one at- potential prey items, but were unable to suc- tempt, it was able to maneuverthe carcass into cessfully consume them because of their size. position, but the grebe’s diameter, its limp Alternative explanations are (1) that the her- wings, or both prevented the heron from swal- ons mistook the grebes for fish or (2) that the lowing it. After attempting to swallow the herons were acting to defend a foraging area. grebe for approximately 15 min, the heron Indeed, an observer at Lake Cachuma report- abandoned the carcass, preened briefly, and ed seeing a foraging heron attack and kill an then flew off. The grebe weighed 255 g American Coot (Fulica americana) with no (weighed after the grebe was frozen and then attempt to eat it (L. R. Mason pers. comm.). thawed), and although that is low body weight The heron we observed, however, expended a for this species (Cullen et al. 1999), it is typ- substantial amount of effort subduing and at- ical of grebes arriving on a wintering area af- tempting to consume the grebe, indicating a ter a migratory flight (Jehl 1997; J. R. Jehl, deliberate act of predation. Evidently, small Jr. pers. comm.). When we examined the grebes are potential prey items for Great Blue grebe, we found no deformities or obvious in- Herons, and herons may attack and kill large dications of poor condition (e.g., loss of pec- birds more commonly than is recognized. toral muscle). On the day previous to our observation (13 ACKNOWLEDGMENTS November 2004), H. R. Pedersen (pers. comm.) observed a Great Blue Heron at Lake We thank K. E. Jirik, the students ofthe Terrestrial Vertebrate Ecology Laboratory course at the Univer- Cachuma in Santa Barbara County, California sity of California-Santa Barbara, and members of the (—130 km southeast ofLake Oso Flaco), cap- Pomona Valley and Golden Gate Audubon Societies ture an Eared Grebe. The heron was foraging for their assistance with observations. H. R. Pedersen and caught the grebe in shallow water, grasped and L. R. Mason kindly shared their observations of it by the neck in the same manner we wit- foraging herons; R. W. Butlerprovided helpful discus- nessed, and submerged it several times. After msiooun;sarnedviJe.weR.r Jperholv,iNd.edV.vaMlcuaCbalnechc,omamnedntasn aonnontyh-e a brief struggle, the grebe escaped and ap- manuscript. peared unharmed (H. R. Pedersen pers. comm.). LITERATURE CITED We know of no previous reports of Great Blue Herons capturing, killing, and attempting Butler, R. W. 1992. Great Blue Heron {Ardea hero- to consume Eared Grebes, or any other bird dias). The Birds ofNorth America, no. 25. species of that size; however, McCanch Cullen, S. A., J. R. Jehl, Jr., and G. L. Nuechter- lein. 1999. Eared Grebe {Podiceps nigricollis). (2003) reported a Grey Heron (Ardea cinerea) The Birds ofNorth America, no. 433. that had choked to death while attempting to Jehl, J. R., Jr. 1997. Cyclical changes in body com- ingest a Little Grebe (Tachybaptus ruficollis). position in the annual cycle and migration ofthe Great Blue Herons have a diverse diet that Eared Grebe Podiceps nigricollis. Journal ofAvi- includes songbirds and mammals of various an Biology 28:132-142. McCanch, N. 2003. Grey Heron choking on Little sizes (Peifer 1979. Butler 1992), and they Grebe. British Birds 96:86. have been observed abandoning large prey Peifer, R. W. 1979. Great Blue Herons foraging for items that they were unable to swallow (R. W. small mammals. Wilson Bulletin 91:630-631.