SUMMER 1989 SHORT COMMUNICATIONS

County Audubon Societyand Boulder County Nature of British Columbia. British Columbia Prov. Mus. Occas. Associationhelped me locate nests.The City of Boulder Pap. No. 17. 163 pp. Open Spaceand Mountain Park Rangers, and G. Craig ERRINGTON,P. L. ANDW. J. BRECKENRIDGE.1938. Food of the Colorado Division of Wildlife, provided helpful habits of buteo hawks in north-central United States. information. R. Weiser and the Getroans allowed me ac- Wilson Bull. 50:113-121. cessto their land and Red-tailed Hawk nests. R. Adams, JONES,J. K., JR., D. C. CARTER,H. H. GENOWAYS,R. B. Gilbert, S. Pederson,and J. Strauch helped identify S. HOFFMANN AND D. W. RICE. 1982. Revised check- pellet contents.D. M. Armstrong, D. L. Evans, B. Jakob, M. R. Lein, R. K. Murphy, and J. R. Parrish helped list of North American mammals north of Mexico, •mproveprevious versions of this paper. I was supported 1982. TexasTech Univ. Occas.Papers No. 80. 22 pp. by a UCD Graduate Fellowshipduring manuscriptprep- KINGERY, H. E. AND W. D. GRAUL. 1978. Colorado aration. bird distribution latilong study. Colorado Div. Wildl. LITERATURE CITED 58 pp. MARR, J.W. 1964. The vegetationof the Boulder area. ADAMCIK, R. S., A. W. TODD AND L. B. KEITH. 1979. Pages34-42. In H. G. Rodeck,ED. Natural history Demographic and dietary responsesof Red-tailed of the Boulder area. Univ. of ColoradoMus. Leaflet No. Hawks during a snowshoehare fluctuation.Can. Field- 13. 100 pp. Nat. 93:16-27. AMERICAN ORNITHOLOGISTS' UNION. 1983. Check-list Department of Environmental, Population, and Or- of North American birds, sixth ed. American Orni- ganismicBiology, University of Colorado, Boulder, thologists'Union. 877 pp. CO 80309. Present address: Animal Behavior Grad- ARMSTRONG, D. M. 1972. Distribution of mammals in uate Group, % Department of Zoology, University Colorado.Univ. KansasMus. Nat. Hist. Monogr.No. 3. of California, Davis, CA 95616. 415 pp. BEEBE,F. L. 1974. Field studies of the Falconiformes Received 18 October 1987; accepted6 March 1989

J. RaptorRes. 23(2):55-56 ¸ 1989The RaptorResearch Foundation, Inc.

Bald Eagle Kills Sharp-shinnedHawk

Jay R. George

Klem (WilsonBull. 97:230-231, 1985) describedseveral The smallaccipiter, judged to b.ea Sharp-shinnedHawk instancesof diurnal raptors killing other diurnal raptor (Accipite,'striatus) based on size and flight characteristics, species.I witnesseda similar incident during raptor mi- made 3 passesat the eagle. Each passwas within centi- gration in the fall of 1985. metersof the bigger bird, causingit to turn quickly from At 1005 H on 28 September1985 two raptors were side to side. Considerable distance from the observer to observedflying toward North Lookoutat Hawk Mountain the birds made preciseobservation difficult, and the ac- Sanctuary, Berks County (40ø35'N, 75ø55'W), in east- cipiter was unobservedfor perhaps3 s. The small raptor central Pennsylvania.The birds were first observedat a was next observedapproximately 20 m below and in front distanceof approximately1000 m andwere approximately of the eagle.The eagle dived but missedthe smaller bird, 50 m apart moving parallel to the ridge in a generally which no longermoved with its previousspeed and agility. WSW direction.The larger of the 2 birds was identified The larger bird made3 unsuccessfulattempts at capturing as an eagle,the secondbird as an accipiter.Less than 10 the accipiter, but each time the smaller raptor pitched s after the initial sightingsa third raptor, a smalleraccip- forward and downward with movements that indicated iter, approachedthe pair from behindand aboveand began possiblewing damage.On the fourth try the eagle suc- harassingthe eagleby divingrepeatedly. At this pointthe cessfullygrasped the small accipiter in its talons. larger accipiter(believed to be a Northern Goshawk[Ac- The eagle, now clearly seen to be an immature Bald czpitergentilis] but identificationwas not certain), turned Eagle (Haliaeetusleucocephalus) carried its catch as it con- to the NW and passedthe observationpoint on the north tinuedits flight parallel to the ridge.The eaglepassed my s•deof the ridge without further interactionwith either of observationsite approximately200 m to the southand 50 the other two raptors. m above.As it did it loweredits head,struck its prey with 56 SHORTCOMMUNICATIONS VOL. 23, NO. 2 its mandible and passedbehind me. The eagle circled ACKNOWLEDGMENTS back briefly and droppedthe small raptor to the ground, I would like to thank Stanley E. Senner and Laurie apparentlydead. The eaglethen resumedits flight to the Goodrichfor reviewingan earlierdraft of thismanuscript WSW. and Daniel Klem, Jr. and Laurie Goodrich for encour- Klem (1985) suggestedthat the causesfor interspecific aging me to write it. killing of raptorsby raptorsinclude: competition for food, competitionfor territoryor breedingsites, and annoyance RD6, Manheim, Pennsylvania 17545. or defense.In the incidentI observed,the Sharp-shinned Hawk repeatedlyharassed the eagle,and the eagledid not Received13 October 1988; accepted6 March 1989 eat the Sharp-shinafter killing it. Thesebehaviors suggest that annoyancewas the cause.