Short Communications Wilson Bulletin 117(2);194—196, 2005 First Record of Bronzed Cowbird Parasitism on the Great-tailed Crackle Brian D. Peer,*-'*'* Stephen I. Rothstein,’ and James W. Rivers* — ABSTRACT. We reportthe firstrecordofBronzed body size of a particular cowbird species Cowbird (Molothnis aeneiis) parasitism on the Great- (Rothstein et al. 2002). tailed Crackle (Quiscaliis mexicamis), which repre- The Bronzed Cowbird is one of the least sents the 96th known host for this cowbird species. studied cowbird species (but see Carter 1986, TfrhoemrSeicnoarldoai,s Mbeaxsiedcoo,ninatphaeracsoiltliezcetdiocnluattcht,hecWolelsetcetrend Peer and Sealy 1999b, Chace 2004) and new Foundation of Vertebrate Zoology. The clutch con- data on its host use are especially valuable and tained four grackle eggs and one Bronzed Cowbird could lead to tests of the hypothesis that egg. This record is unusual because the Great-tailed Bronzed Cowbirds are more specialized in ar- Grackle is extremely intolerant offoreign eggs, eject- eas where they are sympatric with Brown- ing them from their nests almost immediately. As the headed Cowbirds (Peer and Sealy 1999b). gBrreoantzereddeCpothw,bimrodreexhpoasntsdswiiltls ruanndgoeubatneddliysbseturdeiceodrdi-n Here, we report the first record of Bronzed ed. Received 22 July 2004, accepted 19 March 2005. Cowbird parasitism on the Great-tailed Grack- le {Quiscaliis mexicamis), representing the 96th recorded host of this cowbird species. The five species ofbrood parasitic cowbirds The Great-tailed Grackle, like other grackle {Molothnis spp.) differ greatly in the numbers species, is rarely parasitized by cowbirds ofhosts they use. Brown-headed (M. ater) and (Rothstein 1975, Peer and Bollinger 1997, Shiny (M. bonariensis) cowbirds are known Peer et al. 2001, Peer and Sealy 2004b), and to have parasitized more than 200 hosts, while our record represents the first recorded obser- the Giant {M. oryzivorus) and Screaming (M. vation of cowbird parasitism on the Great- riifoa.xiHaris) cowbirds parasitize 10 host spe- tailed Grackle, despite the fact that it is sym- cies or less (Ortega 1998). The Bronzed Cow- patric with four parasitic cowbird species. bird (M. cieneiis) uses an intermediate number There is also no evidence ofconspecific brood ofhosts, with a total of95 known host species parasitism in Great-tailed Crackles (Johnson (Lowther 1995, Sealy et al. 1997, Lowther and Peer 2001). 2004). Lanyon (1992) and Rothstein et al. On 16 April 2003, we discovered the par- (2002) have discussed alternative evolution- asitized clutch in the collection ofthe Western ary scenarios for the evolution ofhost use and Foundation of Vertebrate Zoology in Cama- the relationship between the number of hosts rillo, California. The clutch, which had been used by each cowbird species and its branch- collected on 16 May 1882 by A. Forrer in ing order in the phylogeny of cowbirds. Ad- Presidio, Sinaloa, Mexico, contained four ditional data on host use are needed to resolve Great-tailed Grackle eggs and one Bronzed these issues, especially for the Neotropical Cowbird egg. The clutch was set mark 169,12, cowbird species, in part because the number and catalog number 167555-1+4. The de- of recorded hosts is influenced by various bi- scription stated that incubation was “fresh” ases, such as research effort, range, and even and identity “sure.” The number of known hosts for the ' Dept, ofEcology, Evolution, and Marine Biology, Bronzed Cowbird has increased 500% since Univ. ofCalifornia, Santa Barbara, CA 93106, USA. Friedmann’s (1929) seminal study ofthe cow- -Genetics Program, National Museum of Natural birds. Our discovery of the Great-tailed History, Smithsonian Institution, 3001 Connecticut Grackle as a host will likely be followed by Ave., Washington, DC 20008, USA. additional host records as research is con- Current address: Dept, of Biology, Simpson Col- lege, 701 N. C St., Indianola, lA 50125, USA. ducted in the little-studied southern portion of *Corresponding author; e-mail: this cowbird’s range. In addition, the grackle [email protected] is expanding its range in response to habitat 194 SHORT COMMUNICATIONS 195 modification; thus, the species is encountering dicating that the grackle is a suitable host spe- new hosts (Sealy et al. 1997). Nonetheless, the cies (Peer and Sealy 2004b). Bronzed Cowbird appears to be more restrict- This observation supports Peer and Sealy’s ed with respect to its host species than the (2004b) hypothesis that Bronzed Cowbird par- Brown-headed Cowbird. Brown-headed Cow- asitism may have exerted selection pressure birds parasitize more than two times as many on the egg-ejection behavior demonstrated by hosts as Bronzed Cowbirds in areas where the Great-tailed Grackles. On the other hand, it species occur in equal numbers (Peer and Sea- may be more likely that this ejection behavior ly 1999b). evolved in response to parasitism by the Giant Bronzed Cowbirds were once thought to Cowbird, the eggs of which closely resemble parasitize mostly orioles {Icterus spp.; Fried- grackle eggs, and which also specializes on mann 1963), but this view has changed as parasitizing large, colonial members ofthe Ic- more hosts have been discovered. Only 10 of teridae (Peer and Sealy 2004b). the 96 Bronzed Cowbird hosts are Icterus spe- ACKNOWLEDGMENTS cies, and (including our discovery) only 15% of recorded hosts are members of Icteridae. We would like to thank R. Corado and L. Hall for Host use appears to be influenced by com- allowing us to examine the Western Foundation of munity composition. For example. Peer and Vertebrate Zoology collection. This research was sup- Sealy (1999b) found that the most commonly ported by NSF grant 0078139. parasitized host in southern Texas was the LITERATURE CITED Northern Cardinal {Cardinalis cardinalis), which was much more abundant there than Carter, M. D. 1986. The parasitic behavior of the orioles. Bronzed Cowbird in south Texas. Condor 88:11- : ' asiTthiissm isontheGfrierastt-rteaciolreddedCroabcskerlveast—iopnroobfapbalry- Chac2e5,. J. F. 2004. Habitat selection by sympatric I brood parasites in southeastern Arizona: the influ- i due to the species’ anti-parasite behaviors. ence of landscape, vegetation, and species rich- I The Great-tailed Crackle is 1 of only 30 spe- ness. Southwestern Naturalist 49:24-32. cies in North America known to regularly Friedmann, H. 1929. The cowbirds: a study in the bi- ; eject cowbird eggs (Peer and Sealy 2004a) ology ofsocial parasitism. C. C. Thomas, Spring- ' and they are extremely intolerant of foreign field, Illinois. I eggs. Not only do they reject 100% of exper- Friecdomwabninr,ds.H.U.19S63.NaHtoisontalrelMatuisonesumofBtuhleletpianr,asintoi.c imental Bronzed and Brown-headed cowbird : 233. Washington, D.C. eggs (typically within hours), they also reject Johnson, K. and B. D. Peer. 2001. Great-tailedGrack- conspecific eggs that closely resemble their le {Qiiisccilus mexicanus). The Birds of North own (Peer and Sealy 2()0(), Peer and Sealy America, no. 576. 2()04b). Thus, cowbird parasitism may go Lanyon, S. M. 1992. Interspecific brood parasitism in largely undetected because the cowbird eggs blackbirds (Icterinae): a phylogenetic perspective. 1 Science 255:77-79. ! are ejected before researchers ever see them. Lowther, P. E. 1995. Bronzed Cowbird (Molothrus However, Peer and Sealy (1999b, 2()04b) aencHs). The Birds of Ntirth America, no. 144. I monitored 798 nests daily, beginning just be- Lowther, P. H. 2004. Lists of victims and hosts fore sunrise when Bronzed Cowbirds lay their of the parasitic cowbirds (Molothrus). http://fml. eggs (Peer and Sealy 1999a), and found no fieldmuseum.org/aa/Files/lov\ther/CBList.pdf (ac- evidence of parasitism, suggesting that cow- cessed 4 February 2005). I birds avoid parasitizing grackles because their ()Kn;oA. C’. P. 1998. Cowbirds and other brot>d para- sites. University of Arizona Press, Tucson. j^ eggTshewolualcdk boefepjaerctaesdi.tism is not due to the Pi iK.toBr.thIe).ianfnrdec|Liu.enKt.cBoowibi1riNdCiipaRr.as1i9t9i7s.mloinxpCla'noamtmioonns grackle’s larger size. Similar to Shiny and Gi- Grackles. C'ondor 99:151-161. ;• ant cowbirds. Bronzed Cowbirds parasitize PiiK, B. [).. 11. .1. Homan, and S. G. Seai v. 2001. hosts larger than themselves more ofteti tlum Inlretiuent cowbird parasitismon C’ommonGrack- do Brown-headed Cowbirds. Despite havifig les revisitetl: new records from the NorthernGreat ohantlcyhl5i7ng%s,ofcrtohses-mfaosstseroefdGrBeraotn-tzaeidledCoCwrbaicrkdlse PiFK.tPhleaBi.nBsIr.).oWnaiznledsdon.CS.'oBGwu.lblier.Stdii.anmW1i1.l3s1:o99n909-aB9.u3l.lLeatyiinng11t1i:m1e37of can Hedge from Great-tailed Crackle nests, in- 139. 196 THE WILSON BULLETIN • Vol. 117, No. 2, June 2005 Peer, B. D. and S. G. Sealy. 1999b. Parasitism and parasitism: implications for long-term parasite- egg puncture behavior by Bronzed and Brown- host coevolution. Auk 121:1172-1186. headed cowbirds in sympatry. Studies in Avian Rothstein, S. I. 1975. An experimental and teleonom- Biology 18:235-240. ic investigation ofavian brood parasitism. Condor 77:250-271. Peer, B. D. and S. G. Sealy. 2000. Conspecific brood parasitismandeggrejection inGreat-tailedGrack- Rothstein, S. I., M. A. Patten, and R. C. Pleischer. 2002. Phylogeny, specialization, and brood-para- les. Journal of Avian Biology 31:271-277. site coevolution: some possible pitfalls of parsi- Peer, B. D. and S. G. Sealy. 2004a. Correlatesofegg mony. Behavioral Ecology 13:1-10. rejection in hosts of the Brown-headed Cowbird. Sealy, S. G., J. E. Sanchez, R. G. Campos, and M. Condor 106:580-599. Marin. 1997. Bronzed Cowbird hosts: new re- Peer, B. D. and S. G. Sealy. 2004b. Pate of grackle cords, trends in host use, and cost of parasitism. {Quiscalus spp.) defenses in the absence ofbrood Ornitologia Neotropical 8:175-184. Wilson Bulletin 117(2):196-198, 2005 A Cause of Mortality for Aerial Insect!vores? Muir D. Eaton'’2 and Daniel L. Hernandez*^ — ABSTRACT. A male Eastern Phoebe (Sayornis from streams, individuals often forage low phoebe) was found dead on 15 April 2004, hanging over the water by hawking (MDE pers. obs.). from a piece of monofilament fishing line over the Eastern Phoebes also have been observed Kinnikinic River near River Falls, Wisconsin (Pierce County). The individual was hooked through the catching fish, sometimes hovering over the tongue by a fly-fishing lure. Although fishing tackle water for several seconds before taking the has been reported as a cause of mortality for several prey (Binford 1957). aquatic bird species, further research is needed to de- On 15 April 2004, a male Eastern Phoebe termine whether abandoned trout-fishing lures repre- (sex was subsequently determined by inspec- sent a significantthreatto aerial insectivores.Received 13 September 2004, accepted 28 February 2005. tion of gonads) wmas found dead, hanging ap- proximately 0.5 below a tree branch that was 2 m above a small river (Fig. 1). We The Eastern Phoebe {Sayornis phoebe) is a found the bird —0.8 km downstream from the suboscine flycateher (Tyrannidae) that breeds River Falls dam on the Kinnikinic River near throughout the eastern United States and River Falls, Wisconsin (Pierce County). Clos- southern Canada. It is one of the earliest mi- er inspection revealed that the Eastern Phoebe grants to return in the spring (Weeks 1994). was hanging from the end ofa piece ofmono- Eastern Phoebes are primarily aerial insecti- filament fishing line. We recovered the bird on vores, but they also glean insects from a va- 16 April and deposited it at the Bell Museum riety of substrates (Via 1979). They feed pri- of Natural History at the University of Min- marily in edge habitats (Weeks 1994), includ- nesota (catalogue #MDE-065). ing along stream banks where they fly out The phoebe was hooked through the tongue over the water to capture prey. Flying insects by a fishing lure used for fly-fishing. Presum- compose the majority of the Eastern Phoebe’s ably the line was broken off once it and the diet (Weeks 1994). During hatches of insects lure became entangled in the tree. The lure was a bead-head pheasant-tail nymph, which ' Dept, of Ecology, Evolution, and Behavior, Univ. generically mimics the larval stage of mayfly ofMinnesota, 100 Ecology Bldg., 1987 UpperBuford species (Ephemeroptera). These larvae are Cr., St. Paul, MN 55108, USA. aquatic, thus, this lure does not mimic the nor- 2Current address: Museum of Natural History, mal aerial insects that typically compose the ULnaiwvr.enocfe,KaKnSsa6s6,04D5y-c7h5e61,HalUlS,A.1345 Jayhawk Blvd., Eastern Phoebe’s diet. We hypothesize that the ^Correspondingauthor; e-mail: [email protected] lure was bouncing around at the end of the