Road and Trail Influences on Grizzly Bears and Black Bears in Northwest Montana Author(s): Wayne F. Kasworm and Timothy L. Manley Source: Bears: Their Biology and Management, Vol. 8, A Selection of Papers from the Eighth International Conference on Bear Research and Management, Victoria, British Columbia, Canada, February 1989 (1990), pp. 79-84 Published by: International Association of Bear Research and Management Stable URL: http://www.jstor.org/stable/3872905 Accessed: 02/01/2009 16:26 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=iba. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit organization founded in 1995 to build trusted digital archives for scholarship. We work with the scholarly community to preserve their work and the materials they rely upon, and to build a common research platform that promotes the discovery and use of these resources. For more information about JSTOR, please contact
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ROADANDTRAILINFLUENCES ONGRIZZLY BEARSANDBLACKBEARSIN NORTHWEST MONTANA WAYNEF. KASWORM, MontanaDepartment of Fish,Wildlife,and Parks,475 FishHatcheryRoad,Libby,MT 59923 L.MANLEY, TIMOTHY MontanaDepartment of Fish,Wildlife,and Parks,Box43, Stryker,MT 59933
Abstract: Radio locations from 3 grizzly bears (Ursus arctos) and 26 black bears (U. americanus) in the Cabinet Mountains of northwest Montana were analyzed to determine the effects of roads and trails on seasonal habitat use patterns from 1983 to 1988. Two seasons, spring and fall, were identified based on food habits and habitat use. Distances from radio locations to the nearest open road and trail were compared to distances from random points to the nearest road and trail. Grizzly bears used habitat 0-914 m from open roads less than expected based on availability during spring and fall (P < 0.05). Black bears used habitat 0-274 m from open roads less than
expectedduringspringandusedhabitat0-914 m fromroadsless thanexpectedduringfall. Grizzlybearsusedhabitat0-122 m fromtrailsless thanexpectedduringspring and fall. Black bears used habitat0-122 m from trails less thanexpected duringspring and used habitat0-305 m from trails less thanexpected duringfall. Habitat availabilityappearedrelatedto grizzlybearavoidanceof trails,andblackbearavoidanceof roadsandtrails. Meandistancefromgrizzlybearradiolocationstoa seasonally closed roadincreasedwhen the roadwas opened (P < 0.001), thoughblack bearlocationsdid not (P = 0.324). The benefitsof roadclosures in bearmanagementwere discussed. Int. Conf. Bear Res. and Manage 8:79-84
Avoidanceof humanactivitiesby wildlife hasbecome animportantconsiderationinhabitatmanagement.Human activities in wildlife habitatare often concentratedon roadsor trailsfor resourceextractionor recreation. Elk habitat management recommendationsinclude maximum road densities designed to protect importantelk habitat (Lyon 1979). Cumulative effects models for grizzly bearcalculatereductionsin habitateffectiveness because bears avoid various types of human activities (Weaver et al. 1986). This managementapproachrequiresdelineationof zones of influenceandthe quantificationof the disturbance.The objectivesof ouranalyses were to document and compare seasonal zones of less than or greaterthan expected use adjoining roads and trails for grizzly bears and black bears in the Cabinet Mountains. Fundingfor this study was providedby U.S. Borax and Chemical Corporation,the U.S. Fish and Wildlife Service, Montana Departmentof Fish, Wildlife, and Parks,and the U.S. ForestService. We were assisted in the field by G.W. Brown, H. Carriles,B. Giddings,S.Q. Greer,M.J.Madel,M. Parker,J.S. Picton,andT.J.Thier. D.S. Bennettand K. Kindenprovidedexceptionalservices as pilots. We appreciatereviews of the manuscript by K. Aune,G.W. Brown,B.N. McLellan,T.J.Thier,and 2 anonymousreviewers. STUDY AREA We studiedhabitatuse and populationcharacteristics of grizzly bearsandblackbearsfrom 1983 to 1988 in the CabinetMountainsof northwestMontanaand northern Idaho(48?N, 116?W).The CabinetMountainsconstitute the southernportionof the Cabinet-YaakGrizzly Bear Ecosystem.Approximately90%of the studyareawas on public land administeredby the Kootenai, Lolo, and
PanhandleNational Forests. The Cabinet Mountains Wildernessencompassed381 km2of our study area at higherelevations of the East CabinetMountains. Elevations in the Cabinet Mountains ranged from 610 m along the KootenaiRiverto 2,664 m at Snowshoe Peak. Thestudyareahada Pacificmaritimeclimatecharacterizedby short,warmsummersandheavy, wet winter snowfalls. The lower, drierelevations supportedstands of ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsugamenziesii),whereasgrandfir (Abiesgrandis), western red cedar (Thuja plicata), and western hemlock (Tsuga heterophylla)dominatedthe lower elevation moist sites. Mixed standsof subalpinefir (Abies lasiocarpa), spruce(Picea engelmannii),and mountain hemlock (Tsuga mertensiana) were predominantbetween 1,500 m andtimberline. Mixed standsof coniferous and deciduoustrees were interspersedwith riparian shrubfieldsand wet meadows along the major rivers. Huckleberry(Vaccinium spp.) and mixed shrubfields were largely a result of the wildfires that occurredbetween 1910 and 1929. Effective fire suppressionsince thenhas virtuallyeliminatedwildfireas a naturalforce in creatingand maintainingberry-producingshrubfields. Contemporaryresourceuse by humansin our study areaincludesmineralexplorationandextraction,timber harvest, and recreation. The Cabinet Mountainshave been closed to grizzly bearhuntingsince 1974. Hunting seasons for black bearwere open duringspring(15 Apr31 May) and fall (ca. 6 Sep-30 Nov). Grizzly bear densities were approximately1 bear/250-300 km2and black beardensitieswere approximatelyI bear/2km2in the study area(Kaswormand Manley 1988). METHODS Bears were trappedwith foot snares (Johnson and
80
BEARS-THEIR
BIOLOGY AND MANAGEMENT
Pelton 1980). All capturedgrizzly bears and selected adultblackbearswere fittedwith radiocollars(Telonics Inc., Mesa, AZ) andmonitoredfrom the air and ground. Blackbearselectionemphasizedfemales andgeographical spacing in the study area. Groundlocations were made by triangulationfrom a minimum of 3 points. Grizzly bears received real time motion-sensitiveradio collars. All radiolocationswereobtainedduringthe day, thoughsome monitoringoccurredat night to determine activity patterns. Radio locations at den sites were omitted from the analysis. Locations were plotted on 1:24,000 U.S. Geological Survey (USGS) topographic maps and classified by grizzly bear habitatcomponent (ChristensenandMadel 1982,Servheen1983)andelevation. Distancemeasurementsfromopen roadsandtrails to radio locations were made on the USGS topographic maps to 30 m accuracy. Roads closed to vehicles were classified as trails for the analysis. If open roads were closer to bearlocationsthanthe nearesttrail,the distance to the road was also used as the measurementfor the nearest trail. Locations within the zone of less than expected use for roads were eliminated from the trail analysisto avoid bias. Habitatavailabilityestimatesweredevelopedthrough random point techniques described by Marcum and Loftsgaarden(1980). Use-availabilityanalysisfollowed techniques describedby Neu et al. (1974). Statistical significance was accepted at the 0.05 probabilitylevel. Minimumconvex polygon home rangetechniqueswere used to calculatethe areasampledfor habitatavailability (Hayne 1949). The area sampled was a 1,087-km2 polygondefinedby the rangeof all grizzly bearlocations fromtheportionof theKootenaiNationalForestin which habitatcomponentshad been mapped. Availability of habitatwas estimatedfrom 1,200 randompoints within the polygon. Distance to road and trail,habitatcomponent, and elevation were recordedat randompoints and radio locations. More than 95% of the black bearradio locations fell within this polygon. The random point samplewas used to delineatedistance-to-roadcategories (DRC) and distance-to-trailcategories (DTC). Twenty percentof randomobservationsproduced5 DRCs:(1) 0274 m; (2) 275-914 m; (3) 915-1,859 m; (4) 1,8603,322 m; and (5) >3,322 m. Similarly,20% of random observationsproduced5 DTCs: (1) 0-122 m; (2) 123305 m;(3)306-610m;(4)611-1,128m;and(5)>l,128 m. Habitatuse and food habits data from both species were used to determineappropriateseasonal stratification (Kaswormand Manley 1988). Most obvious differences occurredduringmid-summerwhenberriesripened andbearsshiftedfroma grassandforbdominateddiet to
one composed largely of berries. Two seasons were designated:spring,den exit through31 July;and, fall, 1 August throughden entry. RESULTS Radio locationsof 3 adultgrizzly bears(2 males and 1 female) and 26 adult black bears (9 males and 17 females) were analyzed to determinethe effects of open roadsandtrails. We obtained317 grizzly bearlocations and 1,647 black bearradio locations. Road Influences on Grizzly Bears Of the 317 grizzly bearlocations, 233 were from the airand84 werefromtheground.A significantdifference was detectedin grizzly bearuse of the 5 DRCs between aerialandgroundlocations(X2= 31.65, 1 df, P < 0.001). Groundlocations were usually obtained when animals were closer to roads and were omitted from further analysis. Seasonal Variation. - Spring (n = 134) and fall (n = 99) use of the 5 DRCs was not significantlydifferent (X2= 5.46, 1 df, P = 0.243). Thereforespring and fall locationswere pooled to enlargesamplesizes for subsequentanalysis. Grizzlybearuse of the 5 DRCs was significantly differentfrom expected based on availability (X2= 132.51,4 df, P < 0.001). Grizzlybearsused DRCs 1and2 less thanexpected(P < 0.05) andusedDRCs4 and 5 more thanexpected (Table 1). Use of DRC 3 was not differentfromexpected. Grizzlybearuse of DRCs 1 and 2 combinedwas 20% of expected. IndividualVariation.- Of the 3 grizzly bearsin the sample,all used DRCs 1 and2 less thanexpectedandall usedDRC3 as expected. Individualvariationoccurredin the mostdistantDRCs. One individualusedDRC4 more thanexpected and the other 2 used it as expected. Two individualsused DRC 5 more thanexpected and 1 individual used it as expected. Variationby Sex.- Comparisonsof male andfemale use of the 5 DRCs indicatedsimilar patternsexcept in DRC4. Bothsexes usedDRCs 1and2 less thanexpected, DRC 3 as expected, and DRC 5 more than expected. Femaleuse of DRC4 was greaterthanexpectedandmale use was not differentfrom expected. Influence of Habitat. - Our analysis of how roads affectedgrizzly beardistributionindicatedavoidanceof DRCs 1 and 2. Use of a specific habitatshould have declined relative to the availability of that habitat in DRCs 1 and 2, if bearswere respondingto the road. To examinethis effect, we comparedthe use of each habitat componentwith expected use in each DRC.
INFLUENCES OF ROADSANDTRAILSON BEARS * Kasworm and Manley
81
Table 1. Proportionaluse (U) and availability(A) of distance to road categories (DRC)for grizzlybears and black bears in the CabinetMountains,1983-1988.
DRC 2 275-914 m
DRC 1 0-274 m Species/ Season
n
U
pa
A
U
P
A
DRC 3 915-1,859 m U
P
A
DRC 5 >3,322 m
DRC 4 1,860-3,322 m U
P
A
U
P
A
Grizzly bear Annual
233
0.009 < 0.205
0.073 < 0.201
0.202 = 0.198
0.296 > 0.198
0.421 > 0.198
Black bear Spring Fall
646 573
0.158 < 0.205 0.082 < 0.205
0.180 = 0.201 0.143 < 0.201
0.303 > 0.198 0.290 > 0.198
0.274 > 0.198 0.291 > 0.198
0.085 < 0.198 0.194 = 0.198
a Significantdifferences(P < 0.05) indicatedby sign: < less than,> greaterthan,= no difference.
Of the 10 habitatcomponentswith grizzly bearlocations, samplesizes of use andavailabilitywere adequate only for timber, shrubfieldsnowchute, and graminoid parkhabitatcomponents. These 3 habitatcomponents accountedfor 68% of use and provideda rangeof cover andfood values. Use of timberwas less thanexpectedin DRCs 1 and 2. Use of shrubfieldsnowchutes was less than expected in DRC 1 and, as expected, in DRC 2. Graminoidparkhabitatin DRCs 1 and 2 was used less than expected. These results appearlargely consistent with the hypothesisthatgrizzly bearavoidanceof DRCs 1 and 2 was not relatedto habitatavailability. Trail Influences on Grizzly Bears Grizzly bear radio locations in the 0-914 m zone of influencefromroads(DRCs 1 and2) wereremovedfrom the analysisof the influenceof trails. Of the 283 remaining grizzly bearlocations, 215 were from the air and 68 were from the ground. A significant difference was detectedin grizzly bearuse of the 5 DTCs betweenaerial and ground locations (X2 = 12.89, 1 df, P = 0.012). Groundlocations were usually obtained when animals were closer to trails and were omitted from further analysis. Seasonal Variation. - Spring (n = 124) and fall = (n 91) use of the 5 DTCs was not significantlydifferent (X2= 8.36, 1 df, P = 0.079). Thereforespring and fall locations were pooled to enlargesamplesizes for subsequentanalysis. Grizzly bearuse of the 5 DTCs was significantly differentfrom expected based on availability (X2= 70.56, 4 df, P < 0.001). Grizzly bearsused DTCs 1 and 3 less than expected and used DTC 5 more than expected (Table 2). All other DTCs received use as expected. Grizzly bear use of DTC 1 was 42% of expected. IndividualVariation.- All 3 grizzly bearsused DTC 1 less than expected and all used DTCs 2, 3, and 4 as expected. Individual variation occurred in the most
distant DTC. One individual used DTC 5 more than expected and the other2 used it as expected. Variationby Sex - Comparisonsof male andfemale use of the 5 DTCsindicatedidenticalpatterns.Both sexes used DTC 1 less than expected and DTC 5 more than expected. The remainingDTCs were used as expected. Influence of Habitat. - Our analysis of trail influences on grizzly beardistributionindicatedavoidanceof DTC 1. Use of a specific habitatshould have declined relativeto availabilityin DTC 1, if bearswereresponding to the trail. Again we comparedthe use of each habitat componentwith expected use in each DTC. Grizzlybearuse of timber,shrubfieldsnowchute,and graminoidparkhabitatcomponentswereexaminedin the same manner as the road influence analysis. Use of timber was less than expected in DTC 1. Shrubfield snowchuteand graminoidparkhabitatsin DTC 1 were used as expected. These results appearto indicate that grizzly bear avoidanceof habitatin DTC 1 was at least partiallyrelatedto habitatavailability. Road Influences on Black Bears Of the 1,674 blackbearlocations, 1,219 werefromthe air and 455 were from the ground. A significantdifference was detected in black bear use of the 5 DRCs between aerial and groundlocations (X2= 177.23, 1 df, P < 0.001). As with grizzly beardata,groundlocations were usuallyobtainedwhen animalswerecloser to roads and were omittedfrom furtheranalysis. Seasonal Variation. - Spring (n = 646) and fall = (n 573) use of the 5 DRCs was comparedto availability. Black bear use of the 5 DRCs was significantly differentfromexpectedduringspring(X2= 105.12, 4 df, P < 0.001) and fall (X2 = 101.49, 4 df, P < 0.001). Seasonal variationwas most apparentin DRCs 2 and 5. Black bears used DRCs I and 5 less than expected and used DRCs 3 and 4 more than expected during spring (Table 1). Use of DRC2 was notdifferentfromexpected.
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Table 2. Proportional use (U) and availability (A) of distance to trail categories (DTC) for grizzly bears and black bears in the Cabinet Mountains, 1983-1988.
DTC 2 123-305 m
DTC 1 0-122 m Species/ Season
n
U
pa
A
U
P
A
DTC 3 306-610 m U
P
A
DTC 4 611-1,128 m P U A
DTC 5 >1,128 m U
P
A
Grizzly bear Annual
215
0.098 < 0.234
0.172 = 0.166
0.144 < 0.213
0.177 = 0.189
0.409 > 0.198
Black bear Spring Fall
544 526
0.145 < 0.234 0.068 < 0.234
0.237 > 0.166 0.127 < 0.166
0.261 = 0.213 0.274 > 0.213
0.241 > 0.189 0.276 > 0.189
0.116 < 0.198 0.255 > 0.198
a
Significantdifferences(P < 0.05) indicatedby sign: < less than,> greaterthan,= no difference.
Duringfall, DRCs 1 and 2 were used less thanexpected andDRCs 3 and4 were used morethanexpected. Use of DRC 5 was not differentfromexpected. Black bearuse of DRC 1 was 67% of expected duringspring. Use of DRCs 1 and 2 was 55% of expected duringfall. Individual Variation. - Twenty-threeblack bears provided adequate sample sizes to analyze variation. Fourteenbearsused the closest DRC less thanexpected and2 used it morethanexpected. Nine individualsused DRC 2 less thanexpected. Two bearsused DRC 3 less than expected and 4 used it more than expected. Four bearsused DRC 4 less thanexpected and 7 used it more thanexpected. The most distantDRC received less than expected use from 8 bears and 1 bear used it more than expected. Otherindividualuse was not differentfrom expected. Variation by Sex. - Variation between male and female blackbearuse of the 5 DRCs was apparent.Male black bear use of each of the 5 DRCs was not different fromexpected. Femaleblackbearuse of DRCs 1, 2, and 5 was less thanexpected. Female use of DRCs 3 and 4 was greaterthanexpected. Variationby Female ReproductiveStatus. - Black bear females with cubs were compared to the same females during years when they were alone or were accompaniedby yearlingsfora portionof theyear(n = 8). Use patternsof females with cubs and females without cubs were identical in the 3 closest DRCs. Variation occurredin the 2 most distantDRCs. Both reproductive categoriesused DRC 1less thanexpected,usedDRC 2 as expected,andused DRC 3 morethanexpected. Females with cubs used DRC 4 as expected and used DRC 5 less thanexpected. Females withoutcubs used DRC 4 more thanexpected and used DRC 5 as expected. Influence of Habitat. - Our analysis of how roads affected black bear distributionindicatedavoidance of DRC 1 in spring and DRCs 1 and 2 in fall. Use of a specific habitatshouldhavedeclinedrelativeto availability in DRCs I and 2 if bearswere respondingto the road.
To examine this effect we compared the use of each habitatcomponentwith expected use in each DRC. Of the 12 habitatcomponentswith black bear locations, samplesizes of use andavailabilitywere adequate only for timber,shrubfieldsnowchute,shrubfieldburn, andgraminoidparkcomponents.These4 habitatcomponents accountedfor 79% of use and provideda rangeof cover and food values. Use of timber was less than expected in DRC 1 duringspring and fall. Fall use of timberin DRC2 was not differentfromexpected. Use of shrubfieldsnowchutesin DRCs 1 and2 was not different from expected duringboth seasons. Springand fall use of shrubfieldbur habitatwas less thanexpectedin DRC 1 and as expected in DRC 2. Graminoidparkhabitatin DRCs 1 and 2 received use as expected during both seasons. Black bear avoidance of habitat in DRC 1 appearedpartiallyrelatedto habitatavailabilityduring springandfall. Fallavoidanceof DRC2 appearedlargely relatedto habitatavailability. Trail Influences on Black Bears Black bear radio locations in the 0-274 m zone of influence from roads (DRC 1) were removed from the analysisof the influenceof trails. Of the 1,376remaining black bear locations, 1,070 were from the air and 306 were from the ground. A significant difference was detected in bear use of the 5 DTCs between aerial and groundlocations (X2= 91.83, 1 df, P < 0.000). As with grizzlybeardata,groundlocationswere usuallyobtained whenanimalswerecloserto trailsandwereomittedfrom furtheranalysis. Seasonal Variation. -
Spring (n = 544) and fall
(n = 526) use of the5 DTCswas comparedto availability. Black bearuse of the 5 DTCs was significantlydifferent fromexpectedduringspring(X2= 50.13,4 df, P < 0.001) andfall (X2= 107.02,4 df, P < 0.001). Seasonalvariation was most apparentin DTCs2, 3, and5. Blackbearsused DTCs 1 and5 less thanexpectedand used DTCs 2 and4
INFLUENCES OFROADS ANDTRAILS ONBEARS* Kaswormand Manley
more thanexpected duringspring(Table2). Springuse of DTC 3 was not differentfrom expected. Duringfall, DTCs 1 and2 were used less thanexpectedandDTCs 3, 4, and5 wereusedmorethanexpected. Blackbearuse of DTC 1 was 62%of expectedduringspring. Use of DTCs 1 and 2 was 49% of expected duringfall. Individual Variation. - Twenty-threeblack bears provided adequate sample sizes to analyze individual variation. The closest DTC received less thanexpected use from 14 bears. Two individualsusedDTC2 less than expected and 1 individualused it more than expected. Two bears used DTC 3 more than expected. One bear used DTC 4 less thanexpected and4 bearsused it more thanexpected. The most distantDTC receivedless than expected use from 6 bearsand 2 bearsused it more than expected. Otherindividualuse was not differentfrom expected. Variation by Sex. - Variation between male and female blackbearuse was apparentin the 3 most distant DTCs. MaleandfemaleblackbearsusedDTC 1less than expected and used DTC 2 as expected. Male black bear use of DTCs 3, 4, and5 was not differentfromexpected. Female black bears used DTCs 3 and 4 more than expected and used DTC 5 less thanexpected. Variationby Female ReproductiveStatus.- Black bear females with cubs were compared to the same females during years when they were alone or were accompaniedby yearlingsfora portionof theyear(n = 8). Use patternsof females with cubs and females without cubs were identical in all but the 2 most distantDTCs. Both reproductivecategories used DTC 1 less than expectedandused DTCs2 and3 as expected. Femaleswith cubsusedDTC4 morethanexpectedandusedDTC5 less thanexpected. Femaleswithoutcubs used DTCs 4 and5 as expected. InfluenceofHabitat.- Ouranalysisof trailinfluence on black beardistributionindicatedavoidanceof DTC 1 in spring and DTCs 1 and 2 in fall. Use of a specific habitatshould have declined relative to availability in those DTCs if bears were respondingto the trail. Again we comparedthe use of each habitatcomponentwith expected use in each DTC. Black bear use of timber, shrubfield snowchute, shrubfieldbur, and graminoidpark components were examined in the same manner as the road influence analysis. Use of shrubfieldsnowchutes and shrubfield burs was less than expected in DTC 1 during spring. Springuse of timberand graminoidparksin DTC I was not different from expected. Fall use of all 4 habitat components was less than expected in DTC I and as expected in DTC 2. Black bear avoidance of DTC 1
83
appearedpartiallyrelatedto habitatavailabilityduring spring,howeverfall avoidanceof DTC 1 did not appear relatedto habitatavailability. Fall avoidanceof DTC 2 appearedrelatedto habitatavailability. Influences of Seasonal Road Closures We used radio location data from the Bear Creek drainage to furtherexamine the relationshipbetween roads and bear distributions. Bear Creek had a 4-km segmentof roadthatwas openedto vehicles from 1 July to 15 October. The drainagewas steep-sided and approximately 2.5-km wide over the 6.5-km length upstreamfromthe roadgate. Trafficgenerallyconsistedof passengercarsandpickuptrucks.Averagevehicle passes were 9.3 per day or 4.6 roundtripsper day during 1987. We compareddistancesfrom radiolocationsto the road when it was open to vehicles and when it was closed. A comparisonof airandgroundgrizzlybearlocations in the Bear Creekdrainagedid not indicatea significant differenceand thereforesamples were pooled (t = 1.88, 42 df, P = 0.067). Meandistancefromgrizzly bearradio locationsto theroadincreasedfrom655 m (n = 23) before the opening on 1 July to 1,122 m (n = 21) afteropening (t = -3.77, 42 df, P < 0.001). Argumentscould be made thatbearswere following plantphenologyto higherelevations after 1 July and would thereforebe furtherfrom the road. Meanelevation of grizzly bearradiolocations increasedfrom 1,375 m before 1 July to 1,482 m after 1 July, but the difference was not significant(t = -1.87, 42 df, P = 0.068). Moreover,the meanelevationincrease of 107 m did not appearto be sufficientto accountfor the 467 m increase in distance to the road in such a steep, narrowdrainage. Comparisonsof air and groundblack bear locations did indicatea significantdifferenceandthereforeground locations were omitted from furtheranalysis (t = 3.87, 113 df, P < 0.001). Meandistancefromblackbearradio locationsto theroadincreasedfrom764 m (n = 19)before the roadopenedon 1 July to 927 m (n = 25) after 1 July, but the difference was not significant(t = -1.00, 42 df, P = 0.324). Influence of the Time of Locations All locations used in this analysis were obtained duringdaylighthours. Nocturnaluse of habitatnearopen roadsand trailswould not have been detected. Twentyfour hour monitoringwas conducted to determinethe activitypatternsof grizzlybears. Of 1424-hourmonitoring sessions, 8 recordedactivity largely duringthe daylight hours, 3 recordedactivity largely duringthe early
84
BEARS-THEIR BIOLOGYAND MANAGEMENT
morningand late evening hours,and 3 recordedactivity largelyatnight. Thesedataappearedto indicatethatmost grizzly bear activity occurredduringthe daylighthours and was sampledby our radiolocations. DISCUSSION AND MANAGEMENT IMPLICATIONS Habitatsecurityis an importantaspectof bothgrizzly bearandblackbearhabitatmanagement.Resultsof this studyindicatedthatgrizzly bearsavoidedhabitatwithin 914 m (DRCs 1 and 2) of open roads and black bears avoided habitatwithin 274 m (DRC 1) of open roads. Thoughgrizzly bearsamplesizes were small, this study provideddatafrom a very low densitypopulationwhere samplesizes wereunlikelyto be large. Studiesfromother grizzly bear populationsat higher densities have also found avoidance of roads. Research in southeastern BritishColumbia,found thatgrizzly bearsused the area within 100 m of roadsless thanexpectedon the basis of availability (McLellan and Shackleton 1988). A 58% loss of habitatwas observedwithinthis zone. Archibald et al. (1987) reportedthat female grizzly bear use of habitatwithin 150 m of roads declined 78% duringlog hauling activities associated with timber harvest in a coastal British Columbiaforest. Mattsonet al. (1987) found that grizzly bears in Yellowstone National Park tended to avoid habitatwithin 500 m of roads during springand summerand tendedto avoid habitatwithin 3 kmof roadsduringfall. Blackbearresearchon theeffects of oil developmentcomplexes notedlittle responsefrom bearswithin2 km of activitysites (TietjeandRuff 1983). InnorthernIdaho,YoungandBeecham(1986) foundthat female black bears avoided roadsides and male black bearsused roadsidesin proportionto availability. Trails(includingclosed roads)displacedbothspecies of bearsless thanopen roads. This informationsupports the value of the road closure system for bear habitat management. Mitigationfor mineralandtimberextraction in grizzly bear habitatshould utilize road closures during and after the project to control the volume of activity. Roadandtrailavoidancezones fromthis studyrepresentthebestdatacurrentlyavailablefromthisecosystem. This informationshould be used in the developmentof habitat effectiveness coefficients for the grizzly bear cumulativeeffects model. Twenty-eight percent of all grizzly bear locations occurredin the 3 closest DRCs(60%of the area).Grizzly bear avoidance of high quality habitatnear roads and
trailsmaylessen the opportunityfor individualsto obtain food and increase intraspecificcompetitionby further forcing bears into limited remote habitat. Conversely, 58% of black bear locations occurredin the 3 closest DRCs. Black beartoleranceof disturbancemay provide an opportunityfor this species to exploit habitatin DRCs 1-3 in the relativeabsenceof grizzly bears. LITERATURECITED ARCHIBALD,W.R., R. ELLIS, AND A.N. HAMILTON. 1987.
Responsesof grizzlybearsto loggingtrucktrafficin the RiverValley,BritishColumbia.Int.Conf.Bear Kimsquit Res.andManage.7:251-257. CHRISTENSEN A.G., AND M.J. MADEL. 1982.
Cumulative
effectsanalysisprocessandgrizzlybearhabitatcomponentmapping.U.S. Dep. Agric.,For.Serv.,Kootenai Natl.For.Unpubl.Rep. 37pp. D.W. 1949. Calculation of size of homerange. J. HAYNE, Mammal.39:1-18. JOHNSON,K.G., AND M.R. PELTON.1980. Prebaiting and
snaringtechniquesforblackbears. Wildl.Soc. Bull. 8:46-
54.
KASWORM, W.F., ANDT.L. MANLEY. 1988. Grizzly bear and
of northwest blackbearecologyintheCabinetMountains Montana.Mont.Dep.Fish,Wildl.andParks,Contract Rep. Helena.122pp. forelkasinfluenced L.J. 1979.Habitat effectiveness LYON, by roadsand cover. J. For. 77:658-660. MARCUM 1980. A nonmapping C.L., ANDD. LOFTSGAARDEN.
techniquefor studyinghabitatpreferences.J. Wildl. Manage.44:963-968.
MATrSON,D.J., R.R. KNIGHT,ANDB.M. BLANCHARD.1987.
roadsongrizzly Theeffectsof developments andprimary bearhabitatuseinYellowstoneNationalPark,Wyoming. Int. Conf. Bear Res. and Manage. 7:259-273. 1988. Grizzly MCLELLAN, B.N., ANDD.M. SHACKLETON. bears and resource-extractionindustries:effects of roads on behaviour,habitatuse, anddemography.J. Appl.Ecol. 25:451-460. ANDJ.M.PEEK.1974. A techniquefor NEU,C.W., C.R. BYERS, analysisof utilization-availabilitydata. J. Wildl. Manage. 38:541-545. C. 1983. Grizzlybearfood habits,movements,and SERVHEEN, habitatselection in the Mission Mountains,Montana. J. Wildl. Manage. 47:1026-1035. TIETJE,W.D., ANDR.L. RUFF. 1983. Responses of black bears
to oil developmentin Alberta. Wildl. Soc. Bull. 11:99112. and D. T. PUCHLERZ, D. MATTSON, WEAVER, J., R. ESCANO, DESPAIN.1986. A cumulativeeffects model for grizzly bear managementin the Yellowstone ecosystem. Pages 234-246 in Proc. grizzly bearhabitatsymposium. U.S. Dep. Agric. For. Serv., Gen. Tech. Rep. INT-207. YOUNG, D.D., AND J.J.BEECHAM. 1986. Black bearhabitatuse at Priest Lake, Idaho. Int. Conf. Bear Res. and Manage. 6:73-80.
