HABITAT AND SPATIAL RELATIONSHIPS OF BLACK BEARS IN BOREAL MIXEDWOOD FOREST OF ALBERTA

Transcription

1 HABITAT AND SPATIAL RELATIONSHIPS OF BLACK BEARS IN BOREAL MIXEDWOOD FOREST OF ALBERTA BRIAN. PELCHAT,1 Department f Wildlife Eclgy, University f Wiscnsin, Madisn, WI 5376 ROBERT L. RUFF, Department f Wildlife Eclgy, University f Wiscnsin, Madisn, WI 5376 Abstract: Habitat and spatial relatinships f 47 radi-cllared black bears (Ursus americanus) were studied in 1975 and 1976 n 218 km2 f breal mixedwd frest in east-central Alberta. Mean sizes f areas ccupied by bears were larger (P <.5) in 1976 when fd was scarce than in 1975 when fd was abundant; 12 km2 and 39 km2 in 1976 cmpared t 65 km2 and 19 km2 in 1975 fr males and females, respectively. Bears engaged in 2 types f excursinary mvements away frm areas in which they were usually lcated. Shrt-range excursins ccurred thrughut the nn-denning perid, typically did nt exceed 1 km in distance and 4 days in duratin, and resulted in an expansin f areas ccupied by bears when natural fds were scarce. Lng-range excursins ccurred during late summer and fall each year, averaged 23 km in distance and 47 days in duratin, and were apparently a respnse t annual changes in the distributin f preferred fds. Hme ranges f females, exclusive f shrt-range excursins, were generally stable in size and lcatin each year regardless f fd abundance. Scat analyses indicated the mst imprtant fd-bearing plants were vetchling (Lathyrus sp.), wild sarsaparilla (Aralia nudicaulis), bearberry (Arctstaphyls uva-ursi), blueberry (Vaccinium myrtillides) and hazelnut (Crylus crnuta). Aspen (Ppulus tremulides) stands were the mst abundant and imprtant fd-prducing cver type because it cntained fds eaten by bears during all seasns, whereas muskeg was the prest fd-prducing cver type. Adult females selected aspen (P <.5) and avided muskeg (P <.5) when natural fds were scarce; use f cver types reflected availability when natural fds were abundant. N differences were evident in the use f cver types by females with cubs and thse withut cubs. Adult males selected aspen (P <.5) and avided muskeg (P <.5) each year regardless f fd availability, and avided jack pine (Pinus banksiana, P <.5) when blueberries were scarce there. Int. Cnf. Bear Res. and Manage. 6:81-92 The distributin and abundance f preferred fds are imprtant factrs in the daily lives f black bears. Bears adjust fraging strategies when natural fds are in shrt supply (Hatler 1967, Rgers 1976) and the sizes f bear hme ranges, especially thse f females, may reflect fd availability (Amstrup and Beecham 1976, Garshelis and Peltn 1981). Mrever, Rgers (1976) intimated that bears are nt always able t secure adequate fd and that bears in pr physical cnditin are cmmnly bserved during years when natural fds are scarce. Indeed, Hatler (1967) reprted numerus emaciated bears in Alaska during a year when blueberries (Vaccinium uliginsum) were scarce. Few studies, hwever, have described habitat availability and use amng black bears and nne has fcused n the breal mixedwd frest (Rwe 1959) f Canada. Furthermre, bear-habitat relatinships usually have been determined indirectly thrugh scat analysis (Tisch 1961, Hatler 1967, Beeman and Peltn 198). This study directly examines the relatinships between bears and their habitat in the breal mixedwd frest and incrprates scat analysis and raditelemetry. In this paper we describe the spatial relatinships f bears in respnse t changes in fd distributin and abundance, seasnal habitat use by different age and sex grups, and habitat use in relatin t fds eaten by black bears. 'Present address: Yukn Department f Renewable Resurces, Whitehrse, Yukn Y1A 2C6 Canada. This study is part f a lng-term prject initiated in 1968 by the Alberta Dep. f Energy and Nat. Resur. and cntinued frm 1974 thrugh spring 1978 under the auspices f the Dep. f Wildl. Eclgy, Univ. f Wiscnsin-Madisn. We gratefully acknwledge the field assistance prvided by B. Yung, W. Tietje, T. Kemp, C. Ballweg, G. Kemp, J. Pelchat, and Fish and Wildlife Officers frm the Alberta Dep. f Energy and Nat. Resur. Financial supprt was prvided by the Alberta Dep. f Energy and Nat. Resur. (Fish and Wildl. Div.), the Natl. Sci. Fund. (Grant BMSS ), the Res. Cmm. f the Grad. Schl, Univ. f Wiscnsin-Madisn, Gulf Canada Resurces, Inc., and the Alberta Oil Sands Envirn. Res. Prg. STUDY AREA Field studies were cnducted n 218 km2 f breal mixedwd frest 24 km nrtheast f Edmntn, Alberta. The study area is n the nrth and west shres f Cld Lake and is brdered t the nrth by the Cld Lake Air Weapns Range and t the suth by the Cld Lake Indian Reserve. The suthern bundary als abuts agricultural land which is used primarily fr beef cattle ranching and small-grain farming. The western bundary is the Medley River and the eastern bundary is the Martineau River and the Alberta-Saskatchewan brder (Fig. 1). With the exceptin f river valleys and a 15 m hill n the nrthern bundary, terrain is flat with a mean elevatin f 58 m. Mean temperature fr July is 17 C

2 82 BEARS-THEIR BIOLOGY AND MANAGEMENT grund. Open sphagnum bgs fringed by tamarack (Larix laricina) prevail in the wettest areas. Tw small pen-pit garbage dumps are lcated in the area. The nrthern dump is used year-rund basis by military persnnel, and the suthern dump is used seasnally by campers and cttage wners. The study area is further described by Yung and Ruff (1982), and Tietje and Ruff (198, 1983). Fig. 1. Cld Lake study area (hatched line) shwing majr lakes and rivers, il develpment sites (squares) and garbage dumps (stars). and -19 C fr January. Mean annual precipitatin is 46 cm. Uplands cmprise 76% f the area's land surface. Aspen dminates 53% f the uplands with an understry f aspen, willw (Salix sp.), and rse (Rsa sp.). Grass, blueberry, vetchling, sarsaparilla, and bearberry are cmmn grund plants. Mixed frests f aspen, white spruce (Picea glauca) and jack pine cver 37% f the uplands. The understry is mstly birch (Betula papyrifera), cranberry (Viburnum sp.) and saskatn (Amelanchier alniflia) while cmmn grund plants are bearberry, blueberry, and bg cranberry (Vaccinium vitis-idaea). The remaining uplands are cvered by white spruce (6%) and pine (2%). Species cmmn in the spruce understry are alder (Alnus sp.), white spruce, and rse, whereas birch, cranberry, and saskatn are cmmn in pine understries. Grund cver includes mss, dgwd (Crnus canadensis) and bg cranberry in spruce stands; bearberry, blueberry and bg cranberry are cmmn in pine stands. Muskeg lwlands cmprise the remaining 24% f the area's land surface f which 9% is cvered with a dense frest f scrubby black spruce. Swamp birch (Betula pumila), willw, and black spruce dminate the understry while sphagnum mss (Sphagnum sp.) and Labradr tea (Ledum grenlandicum) mat the METHODS Bears were captured frm May thrugh September each year using Aldrich ft snares and culvert traps. After immbilizatin with phencyclidine hydrchlride (Sernalyn), bears were clr-marked with numbered plastic ear tags and tatted. A premlar was extracted and sectined t determine the age f each bear (Stneberg and Jnkel 1966). Radicllars were placed n 14 female bears in 1975 and n 17 male and 16 female bears in A mbile telemetry system cnsisting f dual yagi antennas and a peak/null switch was used in daily attempts t lcate radi-cllared bears. Each radilcatin was frmed by the intercept f 2 r 3 cmpass bearings frm knwn lcatins. Bears that mved beynd the 5 km range f the mbile telemetry system were lcated frm fixed-wing aircraft. A cver map (1:31,68) f the study area and surrunding terrain was prepared by the Alberta Fr. Serv. frm 1974 aerial phts. All cntinuus blcks f cver in excess f 4 ha, and all streams, rads, trails, and buildings were mapped. The cver map represented verstry vegetatin and classified ptentially merchantable tree species. We used a pint methd t determine the grund cver within each verstry cver type. We sampled 47 sites: 8 in aspen, 4 in pine, 8 in spruce, 16 in mixed frest, 9 in muskeg and 2 in land previusly cleared f timber. All were chsen randmly within areas representative f each cver type. At each site, 3 lines each f 3 paces in length, were marked at?, 12?, and 24? frm true nrth. At each pace, the species f plant less than 1 m in height and whse base was clsest t the te f the bt was recrded. The cver map was used t plt all radilcatins fr hme range determinatin and t measure cver available t and used by bears. Radilcatins were recrded t the nearest 1 m using the Universal Transverse Mercatr (U.T.M.) Grid System. Plts f 3 cmpass bearings ften prduced errr triangles f varius sizes. The radilcatin was taken t be the mean f the crdinates f the vertices.

3 BLACK BEAR HABITAT IN ALBERTA * Pelchat and Ruff 83 Areas ccupied by bears were delineated by the minimum area methd (Mhr 1947). In cases where bears ccupied 2 separate ranges at different times f the year, the ttal area ccupied was taken t be the cmbined area f bth ranges. We als fllwed Burt's (1943:351) definitin f hme range as that area traversed by an animal in its nrmal activities f fd gathering, mating, and caring fr yung. Occupied areas included all radilcatins f bears, whereas hme ranges excluded up t 5% f the lcatins which were mst distant frm lcatin clusters. T delineate cver available t bears, the cver map was partitined using a scaled grid f 2 m2. This grid prduced 4 ha cells that were cded with lcatin and dminant cver type. Summatin f the area and cver cmpsitin within these cells was cnsidered as cver available within each bear's annual and seasnal hme range. This recgnizes that scial, physical, and tpgraphical factrs play a rle in the size and lcatin f hme ranges and, therefre, cver availability (Rgers 1977, Garshelis and Peltn 1981). Only radilcatins fr bears that were independent f each ther were used t determine the cver type utilized by bears. T determine the time perid required fr independence, we pltted the distance against time between 2 cnsecutive lcatins fr a number f bears. After a 24-hur time perid, each bear was frequently mving distances greater than the radius f its hme range. Cnsequently, after 24 hurs we were unable t predict prtins f the hme range that the bear might traverse and hence, this time perid was used as the minimum required fr independence between lcatins. Nt all radilcatins were sufficiently accurate t fix individual bears in a single cver type. Instead, the errr triangle within which the bear was presumably lcated smetimes encmpassed mre than 1 cver type. In 1975, 27% f all radilcatins fell in this categry, as did 14% in Exclusin f these lcatins frm ur analysis wuld have greatly reduced sample sizes. Therefre, we devised a methd based upn prbabilities t allw use f virtually all radilcatins. Fr example, if the cver within an errr triangle was 6% aspen and 4% pine, the prbability that the bear was in aspen r pine was.6 r.4, respectively. Errr triangles cmpsed f a single cver type, as was usually the case, had a prbability f 1. assigned t that cver type. Fr an individual bear, the sum f the prbabilities was equal t the number f radilcatins, and the sum f the prbabilities fr a cver type prvided a relative index f time spent in that cver type. This methd increased the prprtin f usable lcatins t 98%. T evaluate preference r avidance f a given cver type we emplyed the Bnferrni z statistic in cnjunctin with chi-square analysis (Neu et al. 1974). Fresh bear scats were cllected alng radsides, seismic lines and trails, and incidental t trapping and radi-lcating bears. Scats were washed in graduated mesh screens (sizes 4, 7, and 1) t remve small unidentifiable fd items. The remaining items were identified, dried, and weighed t the nearest decigram. Scats that culd nt be analyzed immediately after cllectin were preserved in a 1% frmalin slutin. Thirty-seven permanent 1-m2 plts were established t measure blueberry bimass each year. Eighteen plts were enclsed in wire cages with a 2.5 cm mesh. These were designed t measure blueberry prductin because they excluded birds and small mammals. The remaining 19 plts were enclsed by 15- cm-mesh cages that allwed passage f birds and small mammals and hence measured the availability f blueberries t bears. RESULTS Spatial relatinships amng bears were determined frm telemetric bservatins f 12 females in 1975 and 14 females and 14 males in 1976 (Table 1). Radilcatins indicated that bears made excursins away frm areas in which they were usually lcated. Shrt-range excursins typically did nt exceed 1 km in length r 4 days in duratin, whereas lngrange excursins averaged 47 (range 28-62) days and 23 (range 14-35) km. Mst bears engaged in shrt-range excursins whereas nly a few individuals engaged in lng-range excursins. Bth types f excursins were much mre cmmn in 1976 than in Bears engaged in shrt-range excursins thrughut the entire nn-denning perid. The mean date fr shrt excursins was 1 July (range 7 May-3 Sep, N = 1 bears) fr females in 1975 and 8 July (range 13 Apr-3 Oct, N = 13 bears) and 24 July (range 23 Apr-26 Oct, N = 8 bears) fr females and males, respectively, in Shrt-range excursins were used t differentiate between hme ranges and areas ccupied by bears in a manner similar t that used by Alt et al. (198) and Rgers (1977). Althugh the minimum area

4 E 84 BEARS-THEIR BIOLOGY AND MANAGEMENT C i. A m A S e- g A E A 44 E A (U r r (7 I;,2 r - I <N Ct vr 1O t C ON 'i1 un \ N a t v a r t -R t cd T r-^a,e ^ - (N (( ON _ 6N~ ON = to 'N ^ < s '( - -^ ON sn fi _ methd (Mhr 1947) was used t delineate bth hme ranges and areas ccupied, hme ranges typically excluded thse lcatins assciated with shrtrange excursins. Of the ttal lcatins btained fr any 1 bear, n mre than 5% were excluded (Fig. 2). This methd delineates an area f bear activity in clse keeping with Burt's (1943:351) definitin f hme range. Only bears > 1 year ld and radi-tracked > 1 mnth with > 15 radilcatins were used fr cmparative purpses. The mean sizes f areas ccupied by male and female bears that met these criteria were 65 km2 (Yung 1976) and 19 km2 in 1975, whereas in 1976, these were 12 km2 and 39 km2, respectively (Table 1). These yearly differences were significant (P <.5) and because there was little difference in the number f days bears were tracked each year, it appeared that areas ccupied by bears in 1976 were indeed larger than thse in Hme range sizes f female bears, hwever, were nt significantly different (15 km2 in 1975 vs. 23 km2 in 1976; Table 1). Therefre the larger sizes f areas ccupied by female bears in 1976 were due mstly t an increase in shrtrange excursins that year. Lng-range excursins generally ccurred frm August thrugh September and were always directed suth int agricultural r resrt areas. In 1975, nly 1 such excursin was bserved, that f an adult female (N. 269) between 7 August and 26 September. In 4' i. 44 w r- (U ei t _l _ O 4 4,, cx (U tc N- Cl4 Vn - d N- lq C9 ~ V n (1 C- g an -J m i --?- ON ~ C' I Fig. 2. Cmputer plt f radilcatins fr a female black bear shwing methd f delineating ccupied area and hme range.

5 ii BLACK BEAR HABITAT IN ALBERTA * Pelchat and Ruff , 4 lng-range excursins were bserved, 3 by adult females (Ns. 31, 269, 236) and 1 by an adult male. The male ccupied agricultural land 25 km suth f his hme range between 24 July and 23 August. Bear 31 left her hme range n 5 August and was sht n 1 September at a small lakeside resrt 35 km away. Bear 269 was 14 km suth f her hme range between 24 July and 31 August, and bear 236 was 16 km suth f her hme range between 4 August and 4 Octber. Bears 236 and 269 were mst frequently bserved at a dump during August; hwever, bear 236 extended her excursin suth int agricultural land during September. We als suspected that bear 236 made a similar excursin in 1975 because she was nt fund n her hme range between 29 July and 2 Octber f that year. Telemetry data indicated that hme ranges f adult females displayed little verlap (Fig. 3). Because the study area was trapped intensively, especially in 1976, the lack f verlap was nt simply an artifact f a lw prprtin f radi-cllared females. Where verlap between females ccurred, bears usually utilized the shared area at different times. We als strngly suspect that mst females ccupying shared areas were siblings r females and their ffspring. This was supprted in part by direct bservatins f knwn filial relatinships determined frm marked ffspring. In ther cases, the birthdates f suspected ffspring cincided with years in which the parent female was knwn r suspected t have prduced cubs. Fr example, bears 132 and 133, siblings brn in 1971, were the ffspring f bear 52, as pssibly was bear 139 wh was brn in 1969, the previus cub-bearing year (Fig. 3). Bears 97 and 1 were brn in 1968 and 197, respectively, and were presumably the ffspring f bear 49 wh had cubs in 197 and therefre culd have prduced cubs in Als, bear 1 was trapped nly within the hme range f bear 49 as a cub, yearling, and subadult, as was bear 97 as a subadult. And finally, bear 269, brn in 197, was likely the ffspring f bear 236 because the latter bre cubs in even-numbered years and bth bears made similar lng-range excursins each year. In the latter regard, Rgers (1977) als nted similarities in mvement patterns within families and suggested learning and genetic factrs may be invlved. In cntrast, hme range verlap was the rule amng adult males (Fig. 4) and shared areas were ften used simultaneusly. Fr example, in 1976, hme ranges f 2 adult males verlapped extensively COLD LAKE 5 KM Fig. 3. Hme ranges (exclusive f lng-range excursins) f (A) 11 adult female bears In 1975 and (B) 15 adult female bears in 1976 at Cld Lake, Alberta.

6 86 BEARS-THEIR BIOLOGY AND MANAGEMENT COLD LAKE 5 KM Fig. 4. Hme ranges (exclusive f lng-range excursins) f 12 adult male black bears at Cld Lake in with thse f 6 ther adult males. Mrever, in 1976, less than 3% f the adult males n the study area were radi-cllared, indicating that hme range verlap was cnsiderably mre extensive than depicted. Fd Habits and Weights f Bears Bear scats were cllected n the Cld Lake study area and analyzed fr cntents each year frm 1968 t Hwever, the 1974 and 1975 data were lst and, therefre, the 1975 fd habits reprted here are based upn cular estimates f scat cntents made at the time f cllectin. In 1975, mst bear scats cllected during spring and early summer cntained green vegetatin, prbably vetchling because it was the primary fd cnsumed by bears n ur study area each year since 1968 (Alberta Fish and Wildl. Div., unpubl. prj. rep., 1973). Frm mid-july thrugh mid-august, wild sarsaparilla and ther early-ripening berries were the mst abundant fds in bear scats. By mid-august blueberries had begun t ripen and crrespndingly, a sudden and seemingly cmplete shift in bear diet was bserved. Mst scats cllected frm September t nset f hibernatin cnsisted entirely f blueberries. This was similar t 197 and 1973 when blueberries were abundant n the study area, and a cmpsite f thse years is presented here fr cmparisn (Fig. 5). Bear diets during the spring and early summer f 1976 were similar t thse f 1975 in that bears ate mstly green vegetatin. The percent dry weight f green vegetatin in spring and summer bear scats was 73% and 62%, respectively, mst f which was vetchling (Fig. 5). In additin, bears in spring fed n the buds and catkins f aspen trees and the berries f wild sarsaparilla during the late summer. The animal matter in scats was mstly bait, reflecting scat cllectin near bait sites incidental t trapping. Bear diets during fall, 1976 varied dramatically frm thse f the previus year. Bears maintained a heavy reliance upn vetchling but use f blueberries was almst nnexistent (Fig. 5). Other fall fds imprtant t bears in 1976 were bearberry and hazelnuts. Hrsetail (Equisetum sp.), currants, and gseberries (Ribes sp.), raspberries (Rubus sp.) and saskatns were nt cmmnly eaten by bears and prbably reflected their scarcity n the study area. Cranberries, hwever, were plentiful during the fall f 1976, but few were eaten by bears. Based n the assumptin that fd abundance shuld be reflected in well-nurished bears, we examined the seasnal weights and rates f weight change f individual bears with multiple captures during 1975 and Generally, the mean seasnal weights f bears > 1 year ld were less in 1976 than in 1975 (Table 2). Hwever, weights in spring f 1976 were still cmparable t thse in spring f 1975, and may have reflected the abundance f blueberries the preceding year which enabled bears t enter and emerge frm their winter dens in gd physical cnditin. The nly chrt fr which multiple captures ANIMAL RSAPARILLA BLUEBERRY - 88 SPRING SUMMER FALL SPRING 197/73 PERCENT TRA ANII SUMMER Fig. 5. Cntents f bear scats cllected at Cld Lake during years when blueberries were abundant (197-73) and a year when blueberries were scarce (1976). Shaded areas Indicate green plant matter FALL

7 BLACK BEAR HABITAT IN ALBERTA? Pelchat and Ruff 87 Table 2. Seasnal weights (kg) f black bears in the Cld Lake study area, 1975 and Weight (kg) Spring Summer Fall Adults (> 4 years) Males N Means Females N Means Subadults (2-3 years) Males N Means Females N Means were btained each year was that f subadult males. in virtually every cver type except pine and muskeg, In 1975, mst subadult males (7 f 1) gained weight but was especially cmmn alng radsides, streams thrughut the trapping perid, whereas in 1976, and frest edges. Furthermre, it was abundant bth many (1 f 19) lst weight, especially during the years. Wild sarsaparilla ccurred in mist aspen, spring (3 f 3) and fall (4 f 5) mnths. Weight lss mixed frest, and spruce sites. It appeared singly r by subadult bears indicated nutritinal stress because in small patches, was nt ntably abundant either these bears were still grwing and shuld have gained year, and was largely unavailable t bears after midweight. August. Blueberry and bearberry were fund in mst cver types but were ntably abundant nly in pine Fd Distributin and Abundance and aspen types. Tgether, blueberry and bearberry Based n scat analysis, the mre imprtant fd- cmprised nearly tw-thirds f the grund cver in bearing plant species n the study area were vetchling, pen pine stands (Table 3). wild sarsaparilla, bearberry, blueberry, and aspen buds and catkins. Vetchling was widely distributed Aspen was the mst imprtant fd-prducing cver type n the study area because it was the mst Table 3. Percentit relative frequency f grund cver (< 1 m tall) In each cver type In the Cld Lake study area, Mixed Cleared Aspen Spruce Pine frest Muskeg land Plant species (N = 72) (N = 72) (N = 36) (N = 1,44) (N = 81) (N = 18) Green vegetatin Fruit Bearberry T 1 Blueberry Wild sarsaparilla T 1 T T Other (gseberry, rse, raspberry) Subttal Nn-Fd Items (rck, bare grund, and vegetatin nt eaten by bears) Ttal

8 88 BEARS-THEIR BIOLOGY AND MANAGEMENT abundant (39% f land area) and it cntained fds that were imprtant t bears during all seasns. These included aspen buds and catkins, and vetchling in early spring; sarsaparilla berries and vetchling in summer; and blueberries, bearberries and vetchling in fall. In cntrast, pine cmprised nly 2% f the study area and prduced blueberries and bearberries that were available t bears nly during the fall; mrever, in sme years blueberries were scarce. T measure blueberry prductin and availability t bears, 37 permanent plts were established each year in blueberry patches under stands f pen pine and aspen. Of these plts, 12 were destryed by vandals in 1975 and 15 were destryed in The remaining plts prvided estimates f blueberry bimass each year. The estimated bimass f blueberries prduced and available t bears in 1975 declined significantly (P <.1) in 1976 (Table 4). These declines f 83% in bimass prductin and 88% in bimass available frm 1975 t 1976 were paralleled by nearly identical percentage declines in the number f blueberries prduced (82%) and available (88%), and clearly illustrate the inherent risks t bears fr heavy reliance upn a single fd item r surce. Mrever, the fact that s few blueberries were bserved in bear scats in 1976 may indicate that a mean density f 44 berries per m2 was t lw fr bears t frage efficiently. The bimass f blueberries apparently cnsumed by animals ther than bears in 1975 was 2.9 gm dry weight/m2, r 28% f the bimass prduced. In 1976, it was.9 gm dry weight/m2 r 5% f the bimass f blueberries prduced (Table 4). Cnsequently, it appears that as blueberry abundance decreases the prprtin taken by animals ther than bears increases. Habitat Utilizatin The 6 majr cver types n the study area were aspen, pine, mixed frest, spruce, muskeg, and cleared land. Aspen and pine were single species stands, whereas mixed frest cntained varius cmbinatins f aspen, pine, and spruce. Muskeg encmpassed pen and treed bg, and wet scrubby areas. The remaining vegetatin cnsisted mainly f mature stands f white spruce and small parcels f cleared land. Excluding thse areas cvered by water, the study area was cmprised f 39% aspen, 27% mixed frest, 24% muskeg, 2% pine, and 7% ther vegetatin. Aside frm the hibernatin perid, the number f independent radilcatins that culd be used t assess cver type use was 46 fr 1 female bears in 1975, 1,33 fr 14 females and 581 fr 14 males in 1976, respectively. Use f cver types by adult females in 1976 differed frm that in 1975 (P <.1) and the cver types cntributing mst f the variatin were aspen and muskeg. Adult females spent mre time in aspen in 1976 (45%) than in 1975 (39%), caused largely by a shift in hme range bundaries that made aspen mre available in 1976 (Table 5). These same bears als spent less time in muskeg in 1976 (18% vs. 24% in 1975), again the result f a shift in hme range bundaries. Adult females avided muskeg in 1976 (Table 5). In 1976, 4% f the radi-cllared adult females had cubs with them during the entire instrumentatin perid. We fund n differences in the use f cver between adult females accmpanied by cubs and thse withut cubs that year. Apparently all adult females, regardless f their reprductive status, utilized cver in a similar manner. In 1976 the use f cver by adult male and female bears was significantly different (P <.1). Adult males shwed a strng preference fr aspen, whereas adult females did nt (Table 5). Adult males and females avided muskeg (P <.5) that year, males mre s than females. Adult males avided pine (P <.5). All ther cver types were used in prprtin t their availability. The use f cver by subadult bears is less clear because few females were radi-cllared and 3 f the 5 males were sibling yearlings whse hme ranges Table 4. Numbers and dry weights f blueberries per m2 in 2.5-cm- and 15-cm-mesh exclsures in the Cld Lake study area, 1975 and Number f berries Dry weight f berries (gm) Mesh size N x N x N x N x 2.5 cm cm Mean

9 BLACK BEAR HABITAT IN ALBERTA * Pelchat and Ruff J S C U).2 CZ S cl I 3 3. CO V: r3 z D < S < I~t C l, - ONr) ON r~cic ON tt ~. C -- Rt C I N C, O _ ON 'C O c \ OCN -- c ON N t (ON O c m l O N t- - O O ClONC N -l r-,rt r<^ bi)~~~~~~ u~~~~~~~~~~~- (- c3 CZ 3 Ct E c) CO O - V were small and largely reflected cver used by the parent female. Nnetheless, subadult females preferred aspen in 1975, whereas they avided aspen in 1976, and subadult males avided muskeg in 1976 (Table 5). DISCUSSION Spatial relatinships f bears differed between 1975 and Female bears engaged in mre shrt-range excursins in 1976 and as a result, ccupied larger areas that year. These differences cannt be explained by changes in bear densities r ppulatin age structure which varied little during this study. Fd abundance, hwever, varied greatly and may prvide the mst plausible explanatin fr the bserved changes in the spatial relatinships f bears at Cld Lake. Natural fds were abundant in 1975, especially during the fall when blueberries were s plentiful that mst bear scats were cmprised entirely f blueberries. As a result, bears were heavier and in better physical cnditin in 1975 cmpared t They were able t btain adequate nutritin frm fds clse at hand and there was little need t engage in fraging excursins away frm their hme ranges. In cntrast, in 1976 sme preferred fds were scarce. Many yung bears and females with cubs were in pr physical cnditin, especially during late summer and fall. Green vegetatin, cnsisting mstly f vetchling, made up apprximately 6% f the fd cnsumed by bears thrughut the year. As nted by Jnkel and Cwan (1971) and Rgers (1976), when black bears are frced t feed n grasses and ther green plants that are high in cellulse and relatively nn-digestable, bears lse r nly slwly gain weight. This apparently was the case in In apparent respnse t this shrtage f preferred fds, bears engaged in fraging excursins away frm their hme ranges and ccupied areas larger than thse f bears in Indeed, if areas ccupied by bears fluctuate in respnse t fd abundance, then the size f these areas, as determined by similar methds, shuld prvide a relative index f fd abundance between years and regins. Amstrup and Beecham (1976) suggested that reginal variability in the sizes f areas ccupied by black bears may reflect differences in the quantity, quality and distributin f preferred fds. Their estimates f the sizes f areas ccupied by male (112 km2) and female (49 km2) bears in Idah were nly slightly larger than ur estimates ( 12 km2 fr males, 39 km2 fr females) at Cld Lake in These

10 9 BEARS-THEIR BIOLOGY AND MANAGEMENT figures are cdmparable because methdlgies were similar and Idah bears experienced a shrtage f huckleberries (Vaccinium glbulare) much like the shrtage f blueberries at Cld Lake. Reynlds and Beecham (198) reprted hme range sizes f 6 km2 and 13 km2 fr adult males and females n this same Idah study area in These data are remarkably similar t ur estimates at Cld Lake in the same year. Cmbined with similar estimates f density and ther ppulatin parameters, hme range size may serve as a valuable index t annual and reginal differences in habitat quality. Shrt-range excursins ccurred thrughut the nn-denning perid each year. In 1976, a fd-pr year, these excursins resulted in significant range expansin and suggested that bears were ranging widely in search f new fd surces. Amstrup and Beecham (1976) nted that daily mvements f bears in Idah were significantly lnger in a year when fds were scarce cmpared t a year when fds were abundant. Rgers (1977), hwever, fund that shrt-range excursins f territrial females in Minnesta were mre prnunced during the spring and early summer f each year and suggested that these females were investigating pprtunities fr territrial expansin. Hence, shrt-range excursins may serve a dual functin, but the magnitude f change in hme range during fd-scarce years pints t the frmer as being mst imprtant. Lng-range excursins are thught t be a respnse t changes in the distributin f preferred fds. All excursins f this type were during late summer and fall, and away frm areas where natural fds were scarce and tward agricultural and berry-prducing areas where fds were mre abundant. During the 2 years f this study, mst lng-range excursins (4 f 5) ccurred during 1976 and mst (4 f 5) were undertaken by female bears. These differences hwever, may simply reflect the larger number f bears radi-cllared during the 2nd year as well as the larger number f radi-cllared female bears cmpared t males. Furthermre, the size f male hme ranges may mask the presence f lngrange excursins as defined herein. Bear 269 and prbably bear 236, bth adult females, engaged in lng-range excursins in bth 1975 and The area ccupied by these bears during mst f the year was dminated by treed muskeg and cmpletely devid f pine. As a result, they prbably experienced fd shrtages during late summer and fall f each year, althugh natural fall fds were generally abundant elsewhere n the study area. These bears apparently undertk extensive fraging excursins each year t maintain their nutritinal well-being. Accrding t Bray and Barnes (1967:8), similar types f excursinary mvements have been reprted in Clrad, Pennsylvania, Virginia, Wiscnsin, and Yellwstne Natinal Park. Piekielek and Burtn (1975) and Kelleyhuse (198) reprted excursins f 14 km and 17 km by male black bears int fdrich areas in nrthern Califrnia. In Mntana, Jnkel and Cwan (1971) described areas that did nt supprt bears permanently but were used seasnally by bears frm adjacent areas when fd was abundant there. Adjustments in the spatial relatinships amng bears in respnse t changes in the distributin f preferred fds have als been reprted in Minnesta by Rgers (1977). Wide ranging fraging activities were bserved fr many male and female bears during late summer and early fall and, fr sme bears, these were annual ccurrences. Thirty-seven female bears in Minnesta traveled an average f 27 km t fdrich areas, cmpared t 21 km fr 4 females at Cld Lake. The lngest distance recrded was 21 km by an 11-year ld male in Minnesta. By deleting shrt-range excursins frm adult female hme ranges at Cld Lake, areas were delineated cmparable t thse defined as territries by Rgers (1976) in Minnesta. Territrial verlap appeared greater in the Cld Lake study but this was prbably due t a difference in methdlgies. At Cld Lake, territries were delineated by the minimum area methd (Mhr 1947), whereas in Minnesta they were utlined subjectively by drawing lines between areas used by neighbring territrial females. Regardless, the territries f adult females in these 2 studies shw striking similarities. First, they are ccupied by the same bear in the same area each year and, secndly, they are abut the same size each year regardless f grss variatins in the annual abundance f frage. Alt et al. (198) als fund gegraphic stability fr bear hme ranges in Pennsylvania. Nt all studies f bear spatial relatinships reprt territrial behavir amng adult females. In Washingtn, the hme range distributin f 6 female bears age 3 years and lder shwed cnsiderable verlap (Lindzey and Meslw 1977). Hwever, this study did nt examine filial relatinships r excursinary mvements. In additin, when the hme ranges f nly adult females were mapped, verlap was substantially reduced. Hme range verlap amng adult females in Idah was als extensive, but when the smallest

11 BLACK BEAR HABITAT IN ALBERTA * Pelchat and Ruff 91 areas within which 75% f all lcatins were delineated fr each female, verlap was minimal (Reynlds and Beecham 198). The Idah study als did nt examine kinship relatinships amng female bears. Adult females at Cld Lake were believed t be territrial even thugh ur methd f delineating individual hme ranges shwed verlap between sme female bears (Fig. 4). Mst verlap appeared t be between parent females and their prgeny. Such range sharing has been reprted in Mntana (Jnkel and Cwan 1971 ) and Minnesta (Rgers 1977). Because adult females spend much time within their territries, these areas must prduce sufficient frage t sustain them each year. Hwever, territries prbably did nt evlve t prtect fraging areas because adult females ften frage n fd-rich areas away frm their territries. Mrever, the distributin f frage is ften t unpredictable t be defended (Brwn 1964). Instead, territrial behavir by adult females may be a cmprmise between enhancing the survival f female ffspring and btaining an adequate diet frm a dynamic and hetergeneus fd resurce. By establishing territries, by tlerating female ffspring within these territries, and by subsequently allwing these ffspring t establish territries adjacent t and verlapping that f the parent, adult females enhance the survival f their female ffspring. This type f behavir ensures that the gentypes f the female parent will have a greater chance fr perpetuatin. On the ther hand, because the distributin and abundance f fd is at times highly variable, adult females must ccasinally dispense with territrial behavir t btain an adequate diet. Adult females will make excursins t mre fd-rich areas befre denning, adequate nutritin being tantamunt t survival and pregnancy success (Rgers 1976). Hme ranges f individual bears varied little in size and lcatin frm 1 year t the next and were areas within which bears spent at least 95% f their time. Fr this reasn, cver types within hme ranges were mre representative f cver available t bears than was the cmpsitin f cver in the study area as a whle. This was especially true fr individual adult females wh spent mst f their time in relatively small prtins f the study area. Bears use their habitat fr such activities as resting, feeding, mating, playing and traveling. Because bears are ften n negative energy budgets during much f their active year (Jnkel and Cwan 1971, Pelker and Hartwell 1973) and because fat depsitin befre denning is tantamunt t survival and reprductive success (Rgers 1976), feeding must certainly be the mst imprtant f these activities. Cnsequently, use f cver by bears largely reflects their fraging activities, especially when natural fds are scarce. Fds were indeed scarce in 1976 and, because aspen was the principal fd-prducing cver in the study area, adult female bears spent mre time in aspen that year than in Mrever, because muskeg prvided little in the way f fd fr bears, it was avided by adult females in At Frt McMurray, 3 km t the nrth f Cld Lake, Fuller and Keith (198) reprted that black bears als favred cver types that prduced fd and avided thse that did nt in The prprtin f time bears spent feeding was prbably much less in 1975 because nutritius fd was mre abundant that year. As a result, the use f cver by bears in 1975 was nt nearly as selective as in This may be why, slely n the basis f fd availability, we were unable t explain the bserved use f cver by adult females in Mrever, it demnstrates that when natural fds are abundant, adult females are less selective in their use f available cver. When natural fds are scarce, adult females prefer cvers that prduce fd and avid thse that d nt. Mixed frest and muskeg were nt valuable fdprducing cvers n the study area. Mst plant species in these areas were nn-fd items fr bears and bears never selected these cver types. Muskeg ccurred in the wet lwland areas, was difficult t traverse, and was a cnstant, and presumably aggravating, surce f msquites and blackflies. Mixed frest ccurred in the drier upland areas, was cmprised f stands f the largest trees in the study area, and was 1 f the easier areas t traverse. Bears prbably used mixed frest fr resting cver because it affrded mre prtectin (Herrer 1972) and as travel crridrs between feeding sites. Similarly, Kelleyhuse (1977) nted that black bears in nrthern Califrnia used mixed cnifer frests fr traveling, resting, and escape cver during all mnths f the year. The use f pine by bears reflected the abundance f blueberries in that cver each year. Adult females used pine during the fall f Blueberries, hwever, were s abundant in 1975 that they were reasnably plentiful even after the bears had denned. As a result, blueberries were als a surce f fd fr bears in 1976 and we bserved blueberries in spring bear scats that year. In 1976, adult males avided

12 92 BEARS-THEIR BIOLOGY AND MANAGEMENT pine and adult females appear t have adjusted the bundaries f their hme ranges such that pine was nt available t them. N age-related differences were evident in cver use by male bears. Previusly at Cld Lake, Yung and Ruff (1982) bserved twice the percentage f subadult male (28% f 634) as adult male (14% f 346) radilcatins in the immediate vicinity f dumps. Exclusive f radilcatins in dumps, aspen use by adult males (55% f 297 radilcatins) was nt significantly different than that f subadult males (5% f 455 radilcatins). These percentages are essentially identical t thse f 1976, 59% and 54%, respectively. Hence, subadult males did nt avid habitat ccupied by adult males and the 2 chrts shared large prtins f their ranges with each anther. Hwever, as evidenced by raditelemetry, immediate spatial and tempral separatin was achieved largely thrugh subadult avidance f adults. LITERATURE CITED ALT, G. L., G. J. MATULA, JR., F. W. ALT, AND J. S. LINDZEY Dynamics f hme range and mvements f adult black bears in nrtheastern Pennsylvania. Int. Cnf. Bear Res. and Manage. 4: AMSTRUP, S. C., AND J. BEECHAM Activity patterns f radi-cllared black bears in Idah. J. Wildl. Manage. 4: BEEMAN, L. E., AND M. R. PELTON Seasnal fds and feeding eclgy f black bears in the Smky Muntains. Int. Cnf. Bear Res. and Manage. 4: BRAY,. E., AND V. G. BARNES A literature review n black bear ppulatins and activities. U.S. Dep. Int., Natl. Park Serv. and Clrad Cp. Wildl. Res. Unit, Clrad State Univ., Frt Cllins. 34pp. BROWN, J. L The evaluatin f diversity in avian territrial systems. Wilsn Bull. 76: BURT, W. H Territriality and hme range cncepts as applied t mammals. J. Mammal. 24: FREE, S. L., AND E. MCCAFFREY Reprductive synchrny in the female black bear. Int. Cnf. Bear Res. and Manage. 2: FULLER, T. K., AND L. B. KEITH Summer ranges, cver-type use, and denning f black bears near Frt McMurray, Alberta. Can. Field-Nat. 94:8-83. GARSHELIS, D. L., AND M. R. PELTON Activities f black bears in the Great Smky Muntains Natinal Park. J. Mammal. 61:8-9., AND Mvements f black bears in the Great Smky Muntains Natinal Park. J. Wildl. Manage. 45: HARTLEY, H Maximum-likelihd estimatin frm incmplete data. Bimetrics 14: HATLER, D. F Sme aspects in the eclgy f the black bear (Ursus americanus) in interir Alaska. M.S. Thesis, Univ. Alaska, Cllege. lllpp. HAYNE, D. W Calculatin f size f hme range. J. Mammal. 3:1-8. HERRERO, S Aspects f evlutin f adaptatin in American black bears (Ursus americanus Pallus) and brwn and grizzly bears (U. arcts Linne.) f Nrth America. Int. Cnf. Bear Res. and Manage. 2: JONKEL, C. J., AND I. McT. COWAN The black bear in the spruce-fir frest. Wildl. Mngr pp. KELLEYHOUSE, D. G Habitat utilizatin by black bears in nrthern Califrnia. Int. Cnf. Bear Res. and Manage. 4: KEMP, G. A Bear ppulatin dynamics at Cld Lake, Alberta, Int. Cnf. Bear Res. and Manage. 2: The dynamics and regulatin f black bear (Ursus americanus) ppulatins in nrthern Alberta. Int. Cnf. Bear Res. and Manage. 3: LINDZEY, F. G., AND E. C. MESLOW Hme ranges and habitat use by black bears in suthwestern Washingtn. J. Wildl. Manage. 41: MESLOW, E. C., AND L. B. KEITH Demgraphic parameters f a snwshe hare ppulatin. J. Wildl. Manage. 32: MOHR, C Table f equivalent ppulatins f Nrth American small mammals. Am. Midl. Nat. 37: NEU, C. W., C. R. BYERS, AND J. M. PEEK A technique fr analysis f utilizatin-availability data. J. Wildl. Manage. 38: PIEKIELEK, W., AND T. S. BURTON A black bear ppulatin study in nrthern Califrnia. Calif. Fish and Game 61:4-25. POELKER, R. J., AND H. D. HARTWELL The black bear f Washingtn. Wash. Game Dep. Bil. Bull pp. REYNOLDS, D. C., AND J. J. BEECHAM Hme range activities and reprductin f black bears in west-central Idah. Int. Cnf. Bear Res. and Manage. 4: ROGERS, L Effects f mast and berry crp failures n survival, grwth, and reprductive success f black bears. Trans. Nrth Am. Wildl. and Nat. Resur. Cnf. 41: Scial relatinships, mvements, and ppulatin dynamics f black bears in nrtheastern Minnesta. Ph.D. Thesis, Univ. Minn., Minneaplis. 194pp. ROWE, J. S Frest regins f Canada. Can. Dep. Nrth. Affairs and Nat. Resur., Fr. Br. Bull STONEBERG, R. P., AND C. J. JONKEL Age determinatin f black bears by cementum layers. J. Wildl. Manage. 3: TIETJE, W. D., AND R. L. RUFF Denning behavir f black bears in breal frest f Alberta. J. Wildl. Manage. 44: , AND Respnses f black bears t il develpment in Alberta. Wildl. Sc. Bull. 11: TISCH, E. L Seasnal fd habits f the black bear in the Whitefish Range f nrthwestern Mntana. M.S. Thesis, Univ. Mnt., Missula. 18pp. YOUNG, B. F Numbers, distributin, and structure f a black bear ppulatin in east-central Alberta. M.S. Thesis, Univ. Wisc., Madisn. 35pp.,, AND R. L. RUFF Ppulatin dynamics and mvements f black bears in east-central Alberta. J. Wildl. Manage. 46: