Human Impacts on Bear Habitat Use Author(S): David J. Mattson Source: Bears: Their Biology and Management, Vol
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Human Impacts on Bear Habitat Use Author(s): David J. Mattson 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. 33-56 Published by: International Association of Bear Research and Management Stable URL: http://www.jstor.org/stable/3872901 Accessed: 02/01/2009 16:25 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. 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MATTSON,Interagency Grizzly Bear Study Team, Forestry Sciences Lab,Montana State University,Bozeman, MT 59717 Abstract:Human effects on bearhabitat use aremediated through food biomasschanges, bear tolerance of humansand their impacts, and human tolerance of bears. Large- scale changes in bear food biomass have been caused by conversionof wildlandsand waterwaysto intensive humanuse, and by the introductionof exotic pathogens. Bears consume virtuallyall humanfoods that have been establishedin formerwildlands, but bear use has been limited by access. Air pollutionhas also affected bear food biomass on a small scale and is likely to have majorfuture impacts on bearhabitat through climatic warming. Majorchanges in disturbancecycles and landscape mosaics wroughtby humanshave furtheraltered temporal and spatialpulses of bearfood production.These changeshave broughtshort-term benefits in places, buthave also added long-termstresses to most bear populations. Althoughbears tend to avoid humans,they will also use exotic and native foods in close proximityto humans. Subadultmales and adult females are more often impelled to forage closer to humansbecause of their energeticpredicament and because more secure sites are often preemptedby adult males. Althoughmale bearsare typically responsiblefor most livestock predation,adult females and subadultmales are more likely to be habitu- to ated humansbecause they tend to forage closer to humans. Eliminationof human-habituatedbears predictably reduces effective carryingcapacity and is more likely to be a in factor preservingbear populations where humans are present in moderate-to-highdensities. If humansdesire to preserveviable bearpopulations, they will either have to accept increasedrisk of injuryassociated with preservinghabituated animals, or continueto crop habituatedbears while at the same time preservinglarge tracts of wildlands free from significanthuman intrusion. Int. Conf. Bear Res. and Manage. 8:33-56 Humans(Homo sapiens) have preempteda large part informationpertaining mainly to brown (Ursus arctos) of the Earthfor their use. The attendanttransformation andAmerican black (U. americanus)bears; where appli- and depletion of ecosystems has resulted in extinction cable I also include information on polar bears (U. rates comparable to any prehistoric mass extinctions. maritimus)and Asian black bears (Selanarctos thibeta- Increasingly,humans have turnedtheir attentionto pre- nus). Humansaffect bearsmany ways. Generally,bear servingthe remainingflora andfauna. At the same time, responseto humansand their alterationsis a functionof even in cultureswhere the impetusto preservediversity food biomass changes, bear tolerance of humans and has been greatest,humans have been reluctantto sacrifice human-relatedhabitat changes, and humantolerance of their prerogativeto use lands for their exclusive benefit bears. Where and how bears use their habitat is an (Ehrenfeld 1972). Consequently, much research has integrationof these factors. I use this frameworkto been undertakento determine the level and nature of structuremy presentationof results and interpretation. human use that is compatible with retention of extant flora and fauna. This researchhas characteristicallyfit LITERATUREREVIEW into a minimalisticapproach to managingwildlife habi- tat;that is, how muchcan we do andstill retaina diversity Distributionof Bears and Humans of species sufficient to satisfy our needs? There is relatively little overlap between occupied For bears (Ursidae), this minimalistic approach is bearhabitat and high humandensities (>25/km2) (Fig. 1). evident in harvest strategies, and park and wildlands This is especially true for brown and polar bears and in management. Increasingly sophisticatedmanagement North America, although even European brown bear has entailed cumulative effects analysis (CEA) (Chris- populationsare typically centered on wildlandsand areas tensen 1986); thatis, how do bearpopulations respond to of low-to-moderatehuman densities. The Asian black the total interacting of humanactivities on a given mean- bearexhibits the greatestproportionate overlap of occu- scaled of ingfully piece ground,and does thatfit into our pied range with high densities of humans, although a managementobjectives? How bearsrespond to humans more refined distributionmap for the Asian black bear and their foods is critical input to the CEA and bear will likely show southernChinese populations restricted managementin general. The most sensitivemanagement to islands of forested higher relief terrain(cf. Servheen requires input concerning differences in bear response 1990). The Asian blackbear is notablyabsent from east- among differentsex and age classes, given thatsurvivor- centralChina, where islands of suitablehabitat are absent. and of adult ship productivity females areapparently crit- This mutuallyexclusive distributionof bearsand high ical to populationviability (Knightand Eberhardt1985, densities of humans has probablyresulted from niche Yodzis and Kolenosky 1986, Ramsayand Stirling 1988). differencesand, more importantly,from humanintoler- In this paper, I summarize and interprethow bear ance and predation. Humans inhabit extensive areas habitatuse is affected by humansand their foods. I use never occupied in recent millennia by bears. Humans have also eliminatedbears from many areas, ' including Invited paper much of temperateeastern North America (cf. Cowan Brown bear Black bear m ;c H11 rn Y2 oo tz cl 0 OCCUPIED ASIAN AND AMERICAN z BLACK BEAR HABITAT OVERLAP OF OCCUPIEDBLACK BEAR HABITAT& HUMANDENSITY ) 50 z OVERLAP OF OCCUPIEDBLACK 0 BEAR HABITAT& m HUMAN DENSITY 25-50 m z Fig. 1. Distribution and overlap of high human densities and occupied brown and black bear habitat (Banfield 1958, Bromlei 1965, Cowan 1972, Curry-Lindahl 1972, Herrero 1972, Zunino 1975, Vereschagin 1976, Yi-Ching 1981, Rand-McNally 1986, Clevenger et al. 1987, Elgmork 1987, Jakubiec and Buchalczyk 1987, Verstrael 1988). HUMANIMPACTS ON BEAR HABITAT* Mattson 35 1972, Burk 1979) andAsia (Servheen 1990), andmost of 1969a, Isakovic 1970, Pulliainen 1986, and others). In Europe(Curry-Lindahl 1972). The eliminationof grizzly the Soviet Union, drainagehas affectedca. 13 million ha bearsfrom virtually all of the westernUnited Statesin the (Ceriomuskinand Burminova1969), and has negatively absenceof high humandensities andextensive cropland, impacted brown bear populations (Sharafutdinovand between 1850 and 1930, reflects an extreme case of Kortokov 1976, Vereschagin 1976). human intolerance. Because of these exterminations, DisturbanceandRegeneration Cycles.-Humans have much bear habitatis currentlyunoccupied by bears be- contributedto the frequencyand intensityof fires under cause their progenitorswere killed by humans. primevalconditions in most ecosystems (Wilhelm 1973, Russell 1983, Christensen1988, Peet 1988);in this sense, Native Food Biomass and Habitat Structure humans have influenced bear habitat for millennia. Pathogens and HabitatConversion.-Availability of Human-causedfires were more of a factor in inherently bear foods within occupied bear habitathas been most fire-proneareas such as coastal southeastNorth America dramaticallyaffected by intentionalor accidentalelimi- and lower elevations of the Rocky Mountains,and were nationby humans. This has been effected by large-scale more common near traditionalencampments (Russell conversionof landand waterways to intensivehuman use 1983, Arno 1985, Gruell 1985). Primevalhumans gener- and by introductionof exotic pathogens. ally accentuatednatural fire cycles in a way thatreflected In the course of hydroelectricdevelopment and ma- the dependence of humans on natural habitat cycles nipulation of fisheries, humans have eliminated or re- (Russell