Anna's Hummingbirds with Hymenoptera Impaled on Bills

NOTES

ANNA'S HUMMINGBIRDS WITH HYMENOPTERA IMPALED ON BILLS

MICHAEL C. LONG, Eaton Canyon Nature Center, 1750 N. Altadena Dr., Pasa- dena, California 91107

In November1989, NancyFraser, Eaton Canyon Nature Center staff,observed at her feederin Altadena,Los Angeles County, California, a maleAnna's Hummingbird (Calypte anna) in an apparentlyweakened condition and with a dark "lump" on its bill. The bird was observedfor more than a week, perchingat the feederfor periods of up to severalhours. On 19 Novemberthe hummingbirdwas increasingly lethargic and harassedby other hummingbirdswhen it attemptedto feed. I suggestedthat Fraserattempt to capturethe bird to provideaid and examinethe bill. She was able to removethe birdfrom itsperch by hand,but it expiredwithin minutes. Examination of the lump on the bill revealedthe intact head of yellowjacketwasp (Vespula per•sylvanica),pierced from front to backdirectly between the compoundeyes. The wasp head lay toward the distal end of the bill, approximately4 mm from the tip (Figure 1). In early 1990, RussAnderson brought to Eaton Canyon Nature Center a dead male Anna's Hummingbirdwith a dark, roundedmass impaled about halfwaydown the bill. The bird had been founddead in spring 1989 (precisedate not noted)in a yard at 324 FoothillAvenue, Sierra Madre, Los AngelesCounty. The hummingbird was mummified,still clingingwith both feet to a branchof an acacia(?) tree. Roy Snelling(Section of Entomology,Los AngelesCounty Natural History Museum) examinedthe mass,determining it to be the thorax of a bumblebee(Bombus sp.) (Figure2).

Figure1. Headof a yellowjacketwasp (Vespula pensylvanica) impaled on the billof a male Anna's Hummingbird. Photo by Dede Gilman Western Birds 24:267-269, 1993 267 NOTES

Body fluidsfrom the insectsand perhapsdried sugarsolution from the feeder (notedby Fraser)apparently "glued" the headsto the billsand the birdswere unable to removethem. Both hummingbirdsprobably died becauseof an inabilityto feed properly with the mandiblesheld tightly togetherby the insects'hard, chitinous exoskeletons.Both specimenshave been depositedat the Los Angeles County Natural History Museum(107527 and 107528). A literaturesearch revealed no mentionof insectsor insectparts being found on hummingbirdbills. Hummingbirds are well knownto supplementtheir diet of flower nectarwith smallinsects and other arthropodssuch as aphids,gnats, and spiders. Bees and waspsare not generallyappropriate hummingbird prey itemsbecause of their large sizeand difficultyof handlingrelative to the hummingbird'sbill size and shape.Hummingbirds do, however,"zealously guard" their feedingterritories, driv- ing off hawk moths, butterflies,other hummingbirds,and even bees that might competefor nectar (Carpenteret al. 1983). Miller and Gass(1985) summarizedthe relativelyfew knownpredators of hummingbirds,listing among insects only praying mantids(two instances)and referringto Grant's (1959) descriptionof attackson hummingbirdsby wasps. Bent (1940:382-383) discussedhummingbird and bee interactionsand relatedhis observationsof an Anna's Hummingbirdseen to "thrust its bill through a stragglingmass of the insects"to reach sugar syrup. He also "watchedone attackbees flying around an agavestalk, darting at one after another with open bill as if trying to bite them." Interestingly,Luis Baptista(pers. comm.) describeda femaleAnna's Hummingbirdthat died of starvationimpaled on a rose leaf. He surmisedthat the birdimpaled itself on the leafduring an aggressivechase of an enemy.

Figure2. Thoraxof a bumblebee(Bombus sp.) impaled on the bill of a maleAnna's Hummingbird. Photo by Dede Gilman

268 NOTES

An antagonisticencounter is one explanationfor these bee and wasp parts impaledon hummingbirdbills. It wouldseem that to generatethe forcenecessary for its billto piercea bee or waspthe hummingbirdwould have to havepinned the insect againsta hard surface.If struckin flight, whetherintentionally or by accidental collision,the insectpresumably would be deflectedrather than impaled. Alterna- tively,a hummingbirdmight accidentally pierce a hymenopteranby insertingits beak into a flowercorolla or feedertube containingthe insect. I thank NancyFraser and RussAnderson for carefulobservations and submitting the hummingbirdspecimens. I gratefullyacknowledge the insectidentifications by Roy Snellingand the carefulreview of the manuscriptand helpfulcomments of Kimball Garrett, Tim Manolis, and Luis Baptista. Dede Gilman, photographer extraordinaire,kindly photographed the specimens.

LITERATURE CITED

Bent, A. C. 1940. Life historiesof North Americancuckoos, goatsuckers, hummingbirds,and their allies. U.S. Natl. Mus. Bull. 176. Carpenter,F. L., Paton,D.C., and Hixon, M. A. 1983. Weightgain and adjustment of feedingterritory size in migranthummingbirds. Proc. Natl. Acad.Sci. U.S.A. 80:7259-7263. Grant, J. 1959. Hummingbirdsattacked by wasps.Can. Field-Nat.73:174. Miller, R. S., and Gass, C. L. 1985. Survivorshipin hummingbirds:Is predation important?Auk 102:175-178. Accepted 9 March 1993

81MONIHLIJOURNALONFIELDORNITHOLOGY

[] Excellentpapees on identification,distribution, occurrence, movements and behav•x•r of Palearctic birds [• Regularcomrlbufions on Asian-Pacific birds [] Latestnews en rareand interesti• birds• the NetherlamJsand the Western Paleardlc [] Well producedwith numeroushigh quality colour pholographs [] Yearlyreport on rarebirds in the Netherlands [3 In Englishor with extensiveEnglish summaries

For informalion or a free sample issue,write to' Dulch B•rding,Poslbus 7561 I, 1070 AP Amsterdam,Netherlands

Subscribersto DutchB•rdm g canclaim 25% offa BritishB•rds subscription 269