HABITAT-CAPABILITYMODEL FOR BROWN BEAR IN SOUTHEASTALASKA JOHNW. SCHOEN,Alaska Departmentof Fish and Game, 333 RaspberryRoad, Anchorage, AK 99518 RODNEYW. FLYNN,Alaska Departmentof Fish and Game, P.O. Box 20, Douglas, AK 99824 LOWELLH. SURING,1Alaska Region, U.S. Departmentof AgricultureForest Service, P.O. Box 21628, Juneau, AK 99802 KIMBERLYTITUS, Alaska Departmentof Fish and Game, P.O. Box 20, Douglas, AK 99824 LAVERNR. BEIER,Alaska Departmentof Fish and Game, P.O. Box 20, Douglas, AK 99824 Abstract: Habitat-capabilitymodels are necessary for evaluating the effects of forest management on the management of indicator species (including brown bears [Ursus arctos]) of the Tongass National Forest. Habitat-usedata from 95 radio-collaredbrown bears on Admiralty and Chichagof Islands were used to develop this habitat-capabilitymodel. Each of 20 habitatswas assigned a habitat-capabilityvalue based on bear habitatpreference or best professionaljudgment. The effects of human activity and resourcedevelopment on brown bears were estimated, based on best professional judgment, as reductions in habitatcapability within zones of human influence. Int. Conf. Bear Res. and Manage.9(1):327-337 Once widely distributedacross western North the last 2 decades(see review in Zager and Jonkel America,brown/grizzly bears (Ursus arctos horribilis) 1983, Contrerasand Evans 1986), and several currentlyrange over a significantlyreduced portion of investigationshave recently been completed in the the continent. In 1975, they were declaredthreatened coastalforests of BritishColumbia and Alaska (e.g., in the UnitedStates south of Canada. Loss of habitat Hamilton1987, Schoenand Beier 1990). The brown to humanencroachment is a seriousproblem for bear bear has been selected as a managementindicator managementin the contiguous48 statesand elsewhere species(MIS) in therevised Tongass Land Management (Mattson1990, McLellan1990, Schoen1990, Servheen Plan(U.S. Dep. of Agric. For. Serv. 1991). Habitat- 1990). Throughoutthe world,the futureof manybear capabilitymodels are needed for each MIS on the populations,including brown bears, is inextricably TongassForest. Thesemodels will be used for project- linkedwith forestmanagement (Schoen 1991). level planning and are necessary for providing In North Americatoday, the largestpopulation of informationto evaluatethe cumulativeeffects of forest brownbears occurs in Alaska(Peek et al. 1987) with managementon wildlife habitats and populations. an estimated30,000-40,000 bears (Alaska Department Cumulativeeffects analysis is a relativelynew but of Fish andGame 1978). Brownbears are indigenous importantcomponent of forest planning(Christensen to SoutheastAlaska where they occur throughoutthe 1986,Weaver et al. 1986)and provides an approachfor mainlandcoast and on the islandsnorth of Frederick predictingthe long-termeffects of land-management Sound. Admiralty,Baranof, and ChichagofIslands activitieson brownbear habitat and populations. The have some of the highestbrown bear densities(e.g., modelto be describedevaluates quality of habitatfor 2.6 bears/km2on northernAdmiralty Island) in the brownbears, which is assumedto be relatedto long- world(Schoen and Beier 1990). term carryingcapacity. Habitatsare rated, using Brownbears are one of the specialfeatures of the habitat-preferencedata from Schoenand Beier(1990), Tongass NationalForest. Admiralty,Baranof, and on the basisof theirvalue to bearsduring late summer ChichagofIslands are one of the mostimportant brown when hyperphagicbears are most concentratedand bearhunting regions in Alaska. Tourismand outdoor vulnerableto humanactivities. recreationare also growing industriesin this area. Thisproject was fundedby the AlaskaDepartment of Visitorsto SoutheastAlaska as well as manyresidents Fish and Game and Alaska FederalAid in Wildlife are interestedin an opportunityto observethe brown RestorationProject W-22-7. Additionalsupport for the bear, a symbolof the Americanwilderness. projectwas providedby the Forest Service and the The declinein the rangeand numbers of brownbears GreensCreek Mine. D. Anderson,S. Herrero,B. duringthe past centuryin the contiguous48 stateshas McLellan, and 2 anonymous referees provided heightenedmanagement concern for the species and constructivecriticism and editorial review of the prompted an increase in brown bear research, manuscript, and L. McManus provided technical particularlyhabitat-related studies. Most researchon editing. bear-forestryrelationships has been conductedwithin 1 Present Address: Chugach National Forest, 3301 C St., #300, Anchorage, AK 99503. 328 Int. Conf.Bear Res. and Manage.9(1) 1994 HABITATRELATIONSHIPS avalancheslopes. During early summer (mid-Jun Odum(1971:234) described habitat as theorganism's throughmid-Jul), most bearsmove to forestedslopes "address"or the place it inhabitsin fulfillingits life and alpine/subalpinemeadows where they forage on needs (e.g., food, cover, water). Harrisand Kangas newlyemergent vegetation. (1988) proposedthat the definitionof primaryhabitat Bearsconcentrate along low-elevation coastal salmon explicitlyextends beyond the individualto includean streams from mid-July through early September. area of sufficientsize or configurationto supporta During this late summerseason, 54% of all bear populationover time. We considerthat an effective relocationsoccurred in riparianforest habitat vegetated definitionof bear habitatmust also incorporatethe by a spruce-devils club (Picea sitchensis-Oplopanax influenceof humanactivities (Schoen 1990). horridus)community (Schoen and Beier 1990). During Thehabitat relationships of brown/grizzlybears vary this sameperiod, 66% of all bearrelocations occurred considerablyacross the diverse array of ecosystems withina 160-mband on eitherside of anadromousfish they inhabitfrom the easternRockies, through coastal streams(Schoen and Beier 1990). Althoughthis zone rainforests, and to the Arctic. The AlaskaDepartment includeda varietyof habitats,it was dominatedby the of Fish and Gamebegan brown bear investigations in riparianspruce-devils club community. Bears used this SoutheastAlaska in 1981 with particularemphasis on habitatfor fishingalong river banks, for foragingon habitatrelationships and the influenceof logging and succulentvegetation and berries,and for securityand mining activitieson bear populations. From 1981 thermalcover. through1988, 68 brownbears were radiocollaredon Althoughmost bears (>85%) are associatedwith northern Admiralty Island and 3,020 relocations anadromousfish streamsin late summer,some bears collected(Schoen and Beier 1990). Habitatuse by (primarilyfemales) do not use coastal fish streams radio-collaredbrown bears varied seasonally(P < (Schoenet al. 1986). Those bears (termed"interior" 0.01) (Table1) andis considereda responseto seasonal bears) remain in interior regions of the island differencesin food availabilityand quality. throughoutthe year, foragingprimarily on vegetation Most brown bears emerge from high-elevation and berriesin subalpineand avalancheslope habitat. (>300 m) dens betweenApril and May. After den By mid-September,most bears move to upperelevation emergence,many bears move to low-elevationold- (>300 m) forests, avalancheslopes, and subalpine growthforests, coastal sedge meadows, or south-facing meadowswhere they feed on currant(Ribes spp.) and devilsclub berries before denning. Table 1. Seasonal habitat use by 68 radio-collared brown Winterdenning begins in Octoberand November. bearsa on Admiralty Island, Southeast Alaska, 1982-88.b Mean elevationand slope of 121 den sites of radio- collaredbears from Admiraltyand ChichagofIslands Percentageof habitatuse were 640 m and 35? (Schoen et al. 1987). Fifty-two Summer percentof those dens occurredin old-growthforest on Habitattype Spring Early Late Fall Annual habitat. Althoughcave denning was common AdmiraltyIsland, many dens were excavatedunder Old-growth forest large-diameterold-growth trees or into the bases of Upland forest 55.9 28.2 24.5 30.6 28.4 largesnags (Schoen et al. 1987). Riparianforest 8.7 11.0 53.6 18.8 33.3 The seasonalfood habitsof Admiraltybrown bears were described Beach fringe 6.8 4.9 2.0 1.5 3.1 by McCarthy(1989). Duringspring, the diet of brownbears is dominatedby sedges(Carex forest 3.7 14.0 5.2 10.3 8.4 Subalpine spp.), other green vegetation, roots, and deer Nonforest (Odocoileus sitkensis). Sedges and salmon Avalanche slopes 12.4 15.7 5.5 23.2 11.3 (Oncorhynchusspp.) are the major foods consumed skunk 3.7 18.9 2.8 7.6 8.4 duringsummer, although cabbage(Lysichiton Alpine americanum),devils club berries, and other plants, Estuary 3.8 4.5 5.3 0.6 4.3 berries,and rootsare also used. Duringfall, salmon, Other 5.0 2.8 1.1 7.4 2.8 devilsclub berries, skunk cabbage, sedge, beach lovage dominatethe n relocations 161 772 1,285 340 2,558 roots(Ligusticum spp.), andcurrants diet. The distributionof bears correspondedclosely to the a Interiorbears were not included. seasonalabundance and quality of the food itemslisted b Schoen and Beier (1990). above. Because bears have relatively inefficient ALASKABROwNBROWN BEAR HABITAT MODEL *? Schoen et al. 329 carnivore digestive systems (Bunnell and Hamilton influence. Nine majorhabitat categories were identified 1983) and are active for only part of the year, they for use in this model: old-growth forest, beach-fringe must exploit the most productivefeeding sites available. old growth, subalpine forest, second-growth forest, This often brings bears into conflict with humansusing clearcuts, avalanche slopes, alpine, estuary,