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LITERATURECITED OSGOOD,W.H. 1914. Mammals of anexpedition across northern Peru. Series Field MuseumNatural BRIDGES,W.L. 1948. Wildanimals of theworld. GardenCity Zoology History Publication10:143-185. PublishersCompany, Garden City, New York,USA. B. 1980. distributionand food habitsof CLEVENGER,A.P., M.A. CAMPOS, AND A. HARTASAMCHEZ.1994. PEYTON, Ecology, Tremarctos in Peru. Journalof Brownbear, Ursusarctos, predation on livestockin the spectacledbears, oratus, 61:639-652. Cantabrianmountains, Spain. ActaTheriologica 39:267- Mammalogy 278. SUAREZ,E. 1988. Seasonaldistribution and food habitsof Tremarctos in the of GOLDSTEIN,I. 1991b. Arespectacled bear's tree nests feeding spectacledbears, oratus, highlands Ecuador.Studies on Faunaand Environment platformsor restingplaces? Mammalia 55:433-434. Neotropical 23:133-136. 1991a.Spectacled bear predation and feeding behavior G.H. 1931. Randomobservations on habitatsof South on livestockin Venezuela.Studies on NeotropicalFauna TATE, andEnvironment 26:231-235 Americanmammals. Journal of Mammalogy12:248-256. MONDOLFI,E. 1989. Notes on the distribution,habitat, food habits, status and conservationof the spectacledbear (Tremarctosoratus) in Venezuela.Mammalia 53:525-544. Received: 28 May 2001. MYSTERUD,I. 1973. Behaviorof brownbears (Ursus arctos) at Accepted: 29 March2002. moosekills. NorwegianJournal of Zoology21:267-272. Associate Editor: Immell.

PROBABLE GRIZZLYBEAR PREDATIONON AN AMERICAN BLACK BEAR IN

YELLOWSTONEi a a a IIl ~ ' I Ia NATIONALIaII ! I aI % I _Ii i I PARKi,_ II_a ,. climbing trees (Herrero1985). KERRYA. GUNTHER,Bear ManagementOffice, P.O. Box 168, Due to theirlarger body size, grizzly bearshave a com- YellowstoneNational Park, WY 82190, USA, email: petitive advantageover black bears in large non-forested [email protected] areas (Herrero 1977). Although displacementof black MARKJ. BIEL,Bear ManagementOffice, P.O. Box 168, bears bears from habitathas been YellowstoneNational Park, WY 82190, USA, email: by grizzly high quality mark_biel nps.gov documented(Shaffer 1971, Kendall 1984, Aune 1994), NEILANDERSON, Montana Fish Wildlife and Parks,1400 South interspecific killing of black bears by grizzly bears has 19th,Bozeman, MT59715, USA, email: [email protected] only occasionallybeen reported(Arnold 1930, Jonkeland LISETTE of Fish and WildlifeResources, WAITS,Department Cowan 1971, Murie 1981, Ross et al. 1988, Mattsonet al. Universityof Idaho,Moscow, ID 83844-1136, USA, email: [email protected] 1992). We documentedprobable grizzly bear predationon an Ursus 13:372-374(2002) adult male black bear in Hayden Valley, in centralYNP. HaydenValley is a large (>8,500 ha) non-forestedvalley surrounded the forested CentralPlateau. Flora in the Key words: Americanblack bear,grizzly bear,interspecific killing, pre- by dation, Ursus americanus, Ursus arctos, Yellowstone National Park valley is dominatedby sagebrush(Artemesia spp.) and a variety of forbs, grasses, and sedges (Meagher 1973). Numerousgraminoid-dominated wetlands are presentin the (Pinus contorta)forest Both grizzly bears (Ursus arctos) and Americanblack valley. Lodgepole pine types thatoccur on infertile soils dominatethe forested bears (U. americanus)live in YellowstoneNational Park rhyolite 1990). (YNP), which is located primarilyin Wyoming,USA. In plateau surrounding Hayden Valley (Despain (Picea (Abies stands areas where grizzly bears and black bears are sympatric, Spruce engelmannii)-fir lasiocarpa) are the lodgepole pine zone in temporalisolation and behavioraldifferences likely re- interspersedthroughout areas of more favorable moisture such as duce directcompetition between the species (Aune 1994). regimes pond north and 1978). In the GreaterYellowstone Ecosystem (GYE), grizzly margins, slopes, drainages (Graham bears are active in both the forested and non-for- bears are generallymost active duringnocturnal and cre- Grizzly ested areasof Valley throughoutthe non-denning pusculartimes (Schleyer1983, Holm et al. 1999), whereas Hayden season et al. 1995). Black bearsare mostly ob- black bears are mostly diurnal(Barnes and Bray 1967, (Gunther served within and nearthe of the forestedportions Holm et al. 1999). Grizzly bearsevolved to exploit non- edges of the and far from forest cover in the non- forested habitats,whereas black bears are primarilyfor- valley rarely forested areas (Guntheret al. 1995). est adapted(Herrero 1978). Grizzlies are also generally On 2 1998 we received a reportof a dead black largerthan black bears and much more aggressive in de- August bear on the northeastside of the Yellowstone River in fending themselves and theiroffspring from conspecifics across from the Overlook inter- and other predators(Herrero 1978), whereasblack bears Hayden Valley, Grizzly the Grand road. We investigated typically escape predatorsby runninginto forest cover or pretivesign along Loop SHORTCOMMUNICATIONS 373 the reportand found a dead adult male black bear in tall mm, n = 33) in wolves, and 29 to 41 mm (x = 35 mm, SD sedges on the bankof the river, 174 metersfrom the road. = 4 mm, n = 56) in mountainlions. Predationby wolves Field inspectionof the carcassrevealed that the deadblack can be furtherruled out because in 1998, wolves had only bearhad canine puncturewounds to the head and nose as recentlybeen reintroducedto YNP andno wolves had yet well as a crushed skull and left eye orbital. The penis, establishedterritories in HaydenValley (Smith et al. 1999). baculumbone, andtesticles were bittenoff andfound next Predationby a mountainlion is not likely either. In YNP, to the carcass. There were canine markson the scrotum, mountainlions typicallyinhabit Douglas-fir (Pseudotsuga and the left hind quarterwas partially consumed. The menziesii) and spruce-fir forest types containingnumer- carcass had not been buried. Two fresh scats containing ous rocky canyons and outcrops (T. Ruth, Hornocker vegetationwere observednext to the carcassand near (<3 WildlifeInstitute, Gardiner, Montana, USA, personalcom- meters) the partiallyconsumed hind quarter.The preda- munication,2001). The kill site was located in a large, tor that scavenged and likely killed the black bear prob- non-forested valley bottom without these features, not ably defecated these scats while feeding on the carcass. typical of mountainlion habitatin YNP. Based on canine We collected the black bearcarcass for necropsyto deter- widths alone, we cannotcompletely rule out predationby mine cause of deathand to obtainevidence as to the spe- a black bear because it is possible that an exceptionally cies of predatorthat killed it. We collected the scats found large, old adultmale black bear in YNP might have a 59- next to the dead black bear for DNA analysis to confirm mm lower canine width. However, the identificationof the species of the predator. the predatorybear as a grizzly based on canine widths Laboratorynecropsy indicated the dead black bearhad was also supportedthrough laboratory analysis of DNA been in fair to good physiologic conditiongiven the time extractedfrom the bearscats collected at the kill site. DNA of year (kidneyfat index measured24%), and no evidence extractionand species identificationusing mitochondrial of disease was observed. The carcass (minus the eaten DNA fragmentanalyses (Murphyet al. 2000) unambigu- tissue) weighed 77.6 kg. Based on body size and condi- ously identifiedthe scats collected next to the dead black tion, we estimatedthat the black bear probablyweighed bear as being from a grizzly bear. approximately91 kg prior to being partiallyconsumed. The availabilityof trees as a means of escape through The hide and musculatureof the left side of the head were climbingor hiding was an importantselective force in the tor away, exposing a portionof the skull. The left zygo- evolution of black bears (Herrero1977, 1978, 1985). In matic arch was shatteredand bone fragmentswere miss- this incident, no trackswere left in the lush grass to en- ing. A puncturewound had penetratedthe skull ventral able us to determinethe events that led to the black bear and posteriorto the orbitalprocess. Numerouspuncture being killed. Therefore,we do not know if the black bear wounds were observed in the hide surroundingthe head, was stalked, ambushed,or chased to the kill site. There but no damage was noted to the neck. Although several were no ungulate carcasses nearby that would have at- ribs on the left side of the thoracic cavity were broken, tractedmultiple large carnivores to the area. To reachthe the lack of hematoma and tissue damage to that region potential security of a climbable tree to escape from the indicatedthat the damage occurredpost-mortem. Much kill site, the black bearhad 3 options. The nearestclimb- of the tissue surroundingthe left hind quarterand a por- able tree was a dead snag 72 meters west of the kill site, tion of the large intestine had been eaten. The cause of on a small island (0.21 ha) in the YellowstoneRiver. The death was determinedto be traumato the head. black bear would have had to swim and run throughthe The large numberof puncturewounds inflicted to the river for 68 meters and run 4 meters on land to reach the bear's head made it difficult to locate a matchingpair of snag. The nearest climbable, live trees were in a small canine puncturemarks. However, one set of marks be- (1.2 ha) stand, 129 meters to the southwest, and on the lieved to be caused by the lower canines was observed shore opposite from where the black bear was killed. To near the right mandible. The center-to-centerdistance of reach these trees the black bear would have had to swim these canine puncturemarks was 59 mm, typical of aver- and run throughthe river for approximately118 meters age size, adult male grizzly bearsin the GYE. In grizzly and run 11 meters on land. The nearest climbable trees lower = bears, canine widths range from 35 to 66 mm (x that could be reached without swimming were approxi- = = 53 mm, SD 6 mm, n 35). Based on measurements mately 900 metersnortheast and uphill from the kill site. taken from reference skulls, a lower canine width of 59 These trees were also the nearestcontiguous forest large mm is too to have been large inflicted by even a large enough to potentially have provided escape or hiding black bear, wolf (Canis lupus), or mountainlion (Felis cover. from the GYE. concolor) The distance between lower In areas where grizzly bears and black bears are sym- canines from 37 to 55 mm = = range (x 45 mm, SD 4 mm, patric,differences in morphology,behavior, food prefer- n = in black to = 31) bears, 35 48 mm (x= 40 mm, SD 3 ences, andhabitat selection (Herrero 1978) generallyallow 374 Ursus 13:2002

each species to exploit different subniches and coexist predators,ecology andconservation in a changinglandscape. within common geographicareas (Aune 1994). Holm et Proceedingsof the ThirdBiennial Conference on the Greater al. (1999) reportedoverlap in home ranges of black and Yellowstone Ecosystem. NorthernRockies Conservation and grizzly bears in the GYE. In that study, black bears in- Cooperative,Jackson, Wyoming Yellowstone National Park,Mammoth, Wyoming, USA. cluded more forested habitatswithin their home ranges, HERRERO,S.M. 1977. Black bears: the grizzly's replacement? whereasgrizzly bears selected more nonforestedhabitats The black bear in modem North America. Pages 179-195 (Holm et al. 1999). Guntheret al. over- (1995) reported in D. Burke, editor. Proceedings of the workshop on the lap in areasof activityof grizzly and black bearsthrough- management biology of North American black bear, out mostof YNP,but reported that black bears were seldom Kalispell, Montana,USA. observedfar from forest cover in largenon-forested areas 1978. A comparisonof some features of evolution, such as Pelican (Gunther 1991) and Hayden Valleys. ecology, andbehavior of black and grizzly bears. Carnivore Black bearsmay underutilizelarge non-forested areas due 1:7-17. .1985. Bear attacks-their causes and avoidance. to habitatand food preferences(Aune 1994) or to avoid Winchester Press, New Century Publishers, potentially aggressive interactions with grizzly bears, Incorporated, Piscataway,New Jersey,USA. wolves, and latrans;Herrero Ourob- coyotes (C. 1985). HOLM, G.W., F.G. LINDZEY,AND D.S. MOODY.1999. Interactions servationof into interspecifickilling gives insight (1) po- of sympatricblack and grizzly bears in northwestWyoming. tential selective pressures that may influence the Ursus 11:99-108. distributionof black bears, and (2) subniche separation JONKEL,C, ANDI.M. COWAN. 1971. The black bear in the spruce- between black bears and grizzly bears in YNP. fir forest. Wildlife Monograph27. KENDALL,K.C. 1984. Grizzly bear populationtrend studies, ApgarMountains, Glacier National Park-1983 Progress ACKNOWLEDGMENTS Report.U.S. Departmentof the Interior,National Park We thankG. Holm andan anonymousreviewer, as well Service,Glacier National Park, Montana, USA. as EditorR. Harrisfor commentsthat improved this manu- MATTSON, D.J., R.R. KNIGHT, AND B.M. BLANCHARD. 1992. Cannibalismand on black bears script. D. Smith and K. Murphyprovided additional car- predation by grizzly bears in the Yellowstone 1975-1990. Journal of nivorereference skulls. D. Ireland,T. Ruth,and T. Schock Ecosystem, 73:422-425. assisted with measurementsof canine widths from refer- Mammalogy MEAGHER,M.M. 1973.The bison of YellowstoneNational Park. ence skulls. U.S. Departmentof the Interior,National Park Service, Scientific Monograph Series, No. 1, U.S. Government LITERATURECITED PrintingOffice, WashingtonD.C., USA. MURIE, A. 1981. The grizzliesof MountMcKinley. U.S. ARNOLD, B. 1930. Cannibalbear. Yellowstone Nature Notes Departmentof the Interior,National Park Service, Scientific 7(8):54. MonographSeries, No. 14. U.S. GovernmentPrinting Office, AUNE,K.E. 1994. of blackand grizzly Comparativeecology Washington,D.C., USA. bearson the Rocky MountainFront, Montana. International MURPHY, M.A., L.P. WAITS, AND K.C. KENDALL. 2000. Conference on Bear Research and Management9(1):365- Quantitativeevaluation of fecal drying methods for brown 374. bearDNA analysis.Wildlife Society Bulletin 28:951-957. BARNES, V.G.,AND O.E. BRAY.1967. characteristics Population Ross, P.I.,G.E. HORNBECK, ANDB.L. HOREJSI.1988. Latedenning and activities of black bears in Yellowstone National Park. blackbears killed by grizzlybear. Journal of Mammalogy, Colorado Wildlife Research Colorado Final Report, Unit, 69:818-820. State Fort Collins, Colorado,USA. University, SCHLEYER,B.O. 1983. Activity patternsof grizzly bears in the D. 1990. Yellowstone's of DESPAIN, vegetation: consequences Yellowstoneecosystem and theirreproductive behavior, and environment. Roberts Rinehart,Incorporated history predation,and the use of carrion.Master's Thesis, Montana USA. Publishers,Boulder, Colorado, StateUniversity, Bozeman, Montana, USA. D.C. 1978. beardistribution, use of habitats, GRAHAM, Grizzly SHAFFER,S.C. 1971. Some ecological relationshipsof grizzly food habits, and habitat characterizationin Pelican and bears and black bears of the Apgar Mountains in Glacier Yellowstone National Park. Master's Hayden Valleys, National Park, Montana. Master's Thesis, University of MontanaState USA. Thesis, University,Bozeman, Montana, Montana,Missoula, Montana,USA. K.A. 1991. bear andhuman-induced GUNTHER, Grizzly activity SMITH,D.W., K.M. MURPHY,AND D.S. GUERNSEY. 1999. in Pelican YellowstoneNational Park. modifications Valley, YellowstoneWolf Project: Annual Report, 1998. YCR-NR- Master's Thesis, Montana State University, Bozeman, 99-1, National Park Service, Yellowstone Center for USA. Montana, Resources, YellowstoneNational Park,Wyoming, USA. , M.J. BIEL, K.A. CHURCHILL,AND R.L. DANFORTH.1995. in Yellowstone bear 23 Changing problems management, Received: 30 2001. after the 85-110 in A.P. Curlee, A.M. July years dumps. Pages 21 2002. Gillesberg, and D. Casey, editors. Greater Yellowstone Accepted: February Associate Editor: Harris.