SUMMER 1986 SHORT COMMUNICATIONS 75

Bald EaglePursues and Injures SnowGoose in Flight

RICHARDS. BENNETT,JR., ANDERWIN E. KLAAS

The Bald Eagle (Haliaeetusleucocephalus) employs sev- birdsfell andseparated just beforehitting the groundand eral huntingmethods in capturingavian prey. They have glidedinto a corn stubblefield about 1 km from the road. beenobserved capturing waterfowl (Parris et al. 1980)and As we approachedthe area on foot, we saw an adult ptarmigan(Shetrod et al. 1977) on land by approaching Bald Eagle and an adult SnowGoose standing in alert closeto the ground,and eaglesalso have been seen flying posturesabout 10 m apart. The eagleflushed about 0.5 lowbetween ocean swells, (White 1974)diving from a high km from us, while the goosestood motionlessuntil we altitude,(Meinertzhagen 1959; Shetrod et al. 1977) or were 10 m away.It then flew alongthe ground for about returning to the surfacefrom an underwater dive (Bent 0.5 km. As it flew, we sawblood over much of the rump 1937;Munro 1938)to takesitting birds. All thesemethods area,especially posterior to the left wing.After relocating dependon surpriseand require little or no aerial pursuit. the goose,we again approached. It flushedat about10-15 Brewster (1880) reported Bald Eaglescapturing water- m and flew stronglytoward the refuge lake about 4 km fowl,including wild geesein flight, by swoopingunder the away.We believethe eaglewould have eventuallykilled prey, turning upsidedown, and graspingthe breastof the the gooseon the ground, if we had not intervened. prey with its talons. Although we have been conductingfield studiesof Griffin et al. (1982) during 3 seasonsof field work saw Snow Geese in the fall since 1976, in the middle Missouri many attemptsby Bald Eaglesto kill apparently healthy River valley, this was our first observationof such an waterfowl. Only 5 attempts were successfulof which 1 extendedpursuit of geeseby an eagle.While SnowGoose capture was a Snow Goose(Chen caerulescens caerulescens). flockson wateror land will invariablyflush when an eagle The authorsgive no detailsexcept to say the goosewas flies overhead,the Canada Goose(Branta canadensis) and forceddown into a field and fed upon. ducksrarely do. We have occasionallyobserved-eagles On 21 January 1983, we observedan adult Bald Eagle pursuingindividual SnowGeese for short distancesafter pursue and injure a Snow Goosenear DeSoto National flushingfeeding flocks from cropfields. In eachinstance, Wildlife Refuge locatedin Harrison County, Iowa, and the gooseescaped by diving into tall vegetationor out- Washington County, Nebraska. The weathcr was clear, maneuveringthe eaglein flight. On the basisof the in- witha temperatureof about2 ø C, a slightnorth wind, and tenseresponse of SnowGeese to flying eagles,predation the ground partly coveredby snow. may occur more often than our observationsindicate. At 1621 H, a flock of about 500 Snow Geese was flushed from the ice by a Bald Eaglenear an open-waterarea on DeSotoLake. The flock circledbriefly and flew eastward Journal paper No. J- 11016 of the Iowa Agriculture and from the refugefor severalkilometers, evidently .to feed Home Economics Experiment Station, Ames, Iowa, m surrounding croplands.The geeseflew in a typical ProjectNo. 2427. searchingpattern characterizedby wide wavy lines,low altitude,and circlingover prospectivefields. About 1650 LITERATURE CITED H, a Bald Eagle wasobserved following several hundred meters behind the flock at the same altitude. The flock BENT, A.C. 1937. Life histories of North American birds then gainedaltitude and flew northwestalong a nearly of prey.Part I. U.S.Natl. Mus.Bull. 167:1-409. straightcourse at groundspeeds in excessof 50 kph, as BREWSTER,W. 1880. Prowess of the Bald Eagle measuredon our vehicle'sspeedometer. (Haliaeetusleucocephalus). Bull. Nuttall Ornithol.Club The eaglecontinued to pursueand slowly gained on the 5(1):57-58. flockfor about5 km. At about1700 H, the eagleflew into GRIFFIN, C.R., T.S. BASKETT AND R.W. SPARROWE. the middleof the flockcausing it to suddenlysplit into 2 1983. Ecologyof bald eagleswintering near a water- groups.The lead group continuedflying north while the fowl concentration.U.S. Dept. of Interior, Fish and trailing group briefly circled, as if confused,and then Wildlife Service, Spec. Sci. Report-Wildlife No. continuednorthward. At this point, the eaglepursued a 247:1-12. singlegoose from the flock. On 3 occasions,the goose MEINERTZHAGEN,R. 1959. Piratesand predators.Oliver tried to divebelow the eagle,but eachtime the eaglewould and Boyd, Edinburgh. also dive until it was below the gooseand they would MUNRO,J.A. 1038. The northern Bald Eagle in British' briefly fly horizontally.Finally the goosedove toward a Columbia. WisonBull. 50( 1): 28-35. woodedfencerow; however, the eagle dove and caught PARRIS,S.D., E.E. KLAASAND R.A. WILSON.1980. Coyote the gooseduring the verticaldescent. Although it could steals snow goose from bald eagles. Raptor Res. not be determinedhow the eaglegrasped the goose,both 14(3):88-89. 76 SI-IORTCOMMUmCAT•ONS VOL. 20, No. 2

SI-IERROD,S.K., C.M. WroTE ASD F.S.C. W•LL•AMSOS. Departmentof Animal Ecology,Iowa StateUniversity, Ames, 1977. Biologyof the bald eagleon AmchitkaIsland, Iowa 50011. Present address of first author: Corvallis En- Alaska.Living Bird 15:143-182. vironmental Research Lab, USEPA, 200 S.W. 35th St., Cor- vallis, Oregon 97330. Address of second author: Iowa WroTE, C.M. 1974. Studieson peregrine falconsin the CooperativeWildlife ResearchUnit, Iowa StateUniversity, Aleutian Islands.Raptor Res. Rep. 3:33-49. Ames, Iowa 50011.

Received20 May 1985; Accepted 1 May 1986

OspreyCaptures Gray Squirrel

PETER TAYLOR

At approximately0800 H on 6 February1982, I sawan been a regular feature of its hunting routine. These cir- Osprey(Pandion haliaetus) capture an EasternGray Squir- cumstancessupport the suggestionthat some Ospreys rel (Sciuruscarolinensis) at Blue SpringsState Recreation take prey other than fish in an opportunisticmanner, Area, near Orange City, Florida. Severalsquirrels were withoutthe pressureof poorfishing conditions, inexperi- foragingon the ground,in and arounda picnicsite in a ence, or other constraintson more typical hunting be- partly clearedarea of live oak (Quercusvirginiana) and havior. unidentified palms adjoining the St. Johns River. Using 7x binoculars,I watchedthe Ospreyglide in a shallowdive LITERATURE CITED for about 100 m alonga curvingflight-path. It flew from the river over the clearing,snatched the squirrelfrom the CASTRALE,J.S. ANnJ. McCALL. 1983. Osprey captures ground without pausing,then flew back over the river, mammalat edgeof soybeanfield. Raptor Res. 17:92. where it was lost to view behind trees. KERN,P.R. 1976. Ospreywith muskrat.BlueJay 34:55. The capture occurred about 100 m away; unfortu- LA¾I-IER,W.H. 1984. Osprey preys on Canada Goose nately,my viewof the momentof capturewas obscured by gosling.Wilson Bull. 93:469-470. shrubbery,so I wasunable to observethe reactionsof the PROCTOR,N.S. 1977. Ospreycatches vole. WilsonBull victim,or other squirrels,to the attack.The squirrelwas 89:625. graspedfirmly in the Osprey'stalons, and was immobile; I WILEY,J.W. ANDF.E. LOI-IRER.1973. Additionalrecords did not record whether it was carried in one or both feet. of non-fish prey taken by Ospreys.Wilson Bull. Wiley and Lohrer (1973) reviewedrecords of non-fish 85:468-470. prey takenby Ospreys.These included mammals as large as ground squirrelsand rabbits,as well as a variety of P.O. Box 597, Pinawa, Manitoba, ROE IL0, Canada. birds,reptiles, amphibians and invertebrates.More recent instancesof atypicalprey have been reported by Castrale and McCall (1983), Kern (1976), Layher (1984) and Received8 October 1985; Accepted31 March 1986 Proctor(1977). This is apparentlythe first record of an Ospreytaking a tree squirrel(albeit from the ground), and is one of rather few observations of the actual attack. It is unfortunatethat the ultimateuse of the squirrelcould not be observed. Wiley and Lohrer (1973) recordedat least9 non-fish prey,mainly cotton rats (Sigmodon hispidus), taken by a pair of Ospreysnear Tampa, Florida, in 1972.They suggested that someinland-nesting Ospreys might exploit an abun- dant alternativefood source,since they are presentedwith more opportunitiesfor non-fish prey while travelling between the nest and scattered bodies of water than are coastal-nestingOspreys. The incident describedhere took place alongsidea large, clear river in mild, calm weather under a light overcastsky. The long,stealthy approach and adeptcap- ture by the Osprey suggeststhat this incident.may have