Taxonomy Order Carnivora, Family Mustelidae. Some authors (Miller 1912, Anthony 1928, Ognev 1935, Miller and Kellogg 1955) place the wolverine into its own subfamily, Guloninae, while others (Ellerman and Morrison-Scott 1966, Stroganov 1969, Wilson and Reeder 1993) include it in the subfamily Mustelinae (Pasitschniak-Arts and Larivière 1995). The taxonomic relationship of Old and New World wolverines has been debated for years. At present, most authorities consider Gulo gulo the only extant representative of the genus separating the wolverine into two subspecies, the Old World Gulo gulo gulo and New World Gulo gulo luscus (Kurten and Rausch 1959, Krott 1960, Honacki et al. 1982, Wilson and Reeder 1993). Subspecific designation may be also be warranted for the Vancouver Island wolverine (Gulo gulo vancouverensis) based on variation in skull size and shape from those on the British Columbia mainland (Banci 1982). Although ecotypic variation appears present, no further specific or subspecific separation has been proposed. Species Account Menu General Characteristics The wolverine is the largest terrestrial member of the family Mustelidae. Its appearance is somewhat bear-like, although movement and associated behavior are distinctly characteristic of the weasel. The wolverine is powerfully built, with structural morphology apparently adapted for winter survival. A semiplantigrade posture facilitates travel through deep snow. The skull of the wolverine is robust; powerful dentition and associated musculature enable the wolverine to forage on frozen meat and bone. The dental formula of the wolverine is incisor 3/3, canine 1/1, premolar 4/4, molar 1/2 for a total of 38 teeth. The wolverine's head is broad and rounded, with small eyes and short rounded ears. Its legs are short, with five toes on each foot; posture is considered semiplantigrade, as the metatarsal pads of the hind feet rarely contact the ground (Clint Long unpublished data). Claws are curved and semi-retractile (Banci 1994). Males are typically 30-40% larger than females with males generally weighing 11 to 18 kg and females 6 to 12 kg (Banci 1994). Wolverine pelage is typically a thick, glossy dark brown. A light, silvery facial mask is distinct in some individuals with a pale buff stripe running laterally from the shoulders along the animal's side and crossing the rump just above a long, bushy tail. A white hair patch on the neck and chest is often prominent in some individuals while virtually nonexistent in others. White hair on the digits, feet and forelegs is not uncommon. Wolverines communicate through vocalizations and scent marking. A variety of vocalizations are used in the presence of conspecifics and kits. Chemical communication is accomplished via scentmarking with urine and abdominal rubbing. Although wolverines have well developed anal musk glands, musking appears to be used primarily as a fear-defense mechanism and is associated with cautionary raised tail posture (Long 1987). Contact with humans will usually elicit a vocal as well as chemical response. Species Account Menu Distribution The wolverine has a circumpolar distribution that corresponds with the boreal zone of the northern hemisphere (Kvam et al. 1988 from Pasitschniak-Arts and Larivière 1995). It is found throughout the holarctic taiga and forest tundra of higher latitudes, south to 37 degrees north in North America and 50 degrees north in Eurasia (Wilson and Reeder, 1993 from Pasitschniak-Arts and Larivière 1995). The historical North American distribution of the wolverine included the northern part of the continent southward to the northernmost tier of the United States from Maine to Washington state. It extended south along the Sierra-Cascade axis through Oregon into the southern Sierra Nevada in California and along the Rocky Mountains into Arizona and New Mexico (Grinnell et al. 1937, Hall 1981, Hash 1987). Records of the wolverine within the upper midwest apparently pre-date human settlement, with the animal most likely absent by the early 1900's (Banci 1994). The wolverine has been extirpated from the northern plains states east of Montana (Banci 1994). In California, the historic range of the wolverine included much of the north coastal area and the Sierra Nevada (Grinnell et al. 1937, Schempf and White 1977). Schempf and White (1977:25) described the modern range to include a broad arc from Del Norte and Trinity counties eastward through Siskiyou and Shasta counties, and then southward through the Sierra Nevada to Tulare County. Subsequent reports have enlarged this range to include the White Mountains in eastern Mono County (Kovach 1981). Aside from these broad distributional data, largely based on early fur-trapping data and sporadic reports of unverified sightings, little is known specifically about wolverine occurrence or abundance, and nothing is known about wolverine ecology, in California (Kucera and Barrett 1993). Wolverines likely occupied a wider variety of habitats during pre-settlement times as evidenced by historical presence in upper mid-western states, and fossil evidence of extant representatives in Great Basin habitats of southern Idaho (White et al. 1984). Human encroachment into historically occupied wolverine habitat may have forced the wolverine into its present distribution. Present distribution of the wolverine in the western United States appears to constitute several peninsular extensions of Canadian populations (Hash 1987, Banci 1994). While reports of wolverine sightings persist in the Rocky Mountain states (Banci 1994), only Idaho and Montana report populations of known extent. In Canada, wolverines are sparsely distributed in boreal forests from east to west, and inhabit the Arctic archipelago as far north as Ellesmere Island (Banfield 1987). Until the turn of the century, wolverines inhabited much of eastern Canada except for Prince Edward Island, Nova Scotia, Newfoundland, eastern New Brunswick, Gaspe Peninsula, and Anticosti Island (Banfield 1987, Peterson 1966). Presently, the wolverine is extremely rare in Quebec and Ontario, and there are no recent records from Labrador (Prescott 1983, van Zyll de Jong 1975). In Manitoba and Saskatchewan, numbers appear to have declined, the southern limits have receded to the north, and wolverines are now confined to the northern portions of the provinces (van Zyll de Jong 1975). In Alberta, the species once occurred in all coniferous forests of the province, but now is found only in remote areas in the north and in the Rocky Mountains (Soper 1964). Wolverine occur throughout mainland British Columbia, except for the southern agricultural areas, and throughout the Yukon Territory and mainland Northwest Territories, with an estimated population of 4,200 south of 66 degrees (Banci 1987). They occur continuously in mainland Alaska (LeReseche and Hinman 1973) but only on some of the southeastern islands (Banci 1994). Records from the Canadian arctic islands are spatially and temporally sporadic (Banci 1994). In Eurasia, wolverines are found from Scandinavia eastward through eastern Europe, Siberia, and Asia (Ewer 1973, Makridin 1964, Stroganov 1969, Wilson and Reeder 1993, Pasitschniak-Arts and Larivière 1995). Records from Scandinavia show that wolverines occur in low population densities (Nowak and Paradiso 1983). Most animals are concentrated in the mountain chain of northern Norway and Sweden, and along the south-central Norwegian mountains (Pasitschniak-Arts and Larivière 1995). In Sweden, wolverines are restricted to remote areas in the northwest (Pasitschniak-Arts and Larivière 1995). The numbers appear to be increasing; however, the distribution is very irregular (Bjärvall 1982). In 1986, a maximum of 40 wolverines was recorded in Finland, and the species is now considered endangered (Pulliainen 1988). Wolverines are also found in the tundra and forest zones of eastern Europe, Russia, and northern Asia (Pasitschniak-Arts and Larivière 1995). In western Siberia, wolverines are widely distributed in the tundra and taiga, and are relatively common in extreme eastern Russia (Stroganov 1969, Pasitschniak-Arts and Larivière 1995). Species Account Menu Fossil Record The fossil history of the Mustelidae has not been well documented because most members were small and forest-dwelling (Pasitschniak-Arts and Larivière 1995). The earliest known mustelids were from late Eocene deposits, and a few marten-like animals were found in the Oligocene (Kurtén and Anderson 1980). Towards the end of the Miocene, recognizable martens were present. Quaternary mustelids survived in nearly all habitats from the arctic tundra to tropical rainforests (Kurtén and Anderson 1980). The largest of the Mustelinae, Gulo, is a holarctic genus specialized for feeding on larger vertebrate prey (Pasitschniak-Arts and Larivière 1995). The wolverine has no exact counterpart in the tropics (Eisenberg 1981). Gulo is descended from Plesiogulo, a large Miocene and Pliocene form (Kurtén and Anderson 1980). The genus Plesiogulo originated in Asia and migrated to North America between 7.0 and 6.5 million years ago (Harrison 1981). Plesiogulo was apparently derived from marten-like ancestors originating from an early Miocene member of the genus Martes (Kurtén 1968). Wolverines from the Old and New Worlds were formerly considered to be separate species (Cowan 1930, Miller 1912); however, Kurtén and Rausch (1959) found the two populations to be only subspecifically distinct. Bryant (1987) examined Gulo gulo from the Pleistocene and concluded that any division of Gulo into two species was arbitrary. Studies of Quaternary remains indicate evolutionary progression within a single species, with differences among populations not being substantial enough to warrant separation into two distinct species (Bryant 1987, Pasitschniak-Arts and Larivière 1995). Species Account Menu Reproduction The mating system of the wolverine appears to be polygamous (Rausch and Pearson 1972). Females are believed to be monestrous and, in the wild, breed from May to August (Wright and Rausch 1955, Rausch and Pearson 1972). Recent studies of captive animals show that females generally come into estrus from June to early August (Mehrer 1976). Increased vaginal cornification occurs from mid-June through early July; this likely corresponds to the time when most matings occur in the wild (Mead et al. 1991, Pasitschniak-Arts and Larivière 1995). Late-stage spermatids and spermatozoa are found in the testes as early as March (Mead et al. 1991). In adult captive wolverines, maximal size of testes and elevated testosterone levels were attained in early April and maintained through early July. Testicular regression began by late July and was complete by mid-August (Mead et al. 1991). During the breeding season, males usually remain close to females, but females take the lead and initiate moves when pairs travel (Magoun 1985). Typically, males will mount females from behind, with forelegs clasping the female's sides. The scruff of the female's neck is often grasped, particularly if she attempts to move (Magoun and Valkenburg 1983). Ovulation is believed to be induced by coitus (Mead et al. 1993). Wolverines exhibit delayed implantation. Fertilized eggs remain in the blastocyst stage until nidation occurs, usually from November to March (Banci and Harestad 1988). Post-implantation following nidation of the blastocyst is about 30-50 days (Mead et al. 1993, Rausch and Pearson 1972, Pasitschniak-Arts and Larivière 1995). Parturition occurs from January through April, with most females giving birth before late March (Pulliainen 1968). Litter size averages 2-3 kits. Young are born fully furred with eyes closed and teeth not erupted (Pasitschniak-Arts and Larivière 1995). At birth their fur is white, they weigh an average of 84.0 grams, and have a crown-rump length of 121.0 mm (Pasitschniak-Arts and Larivière 1995). Young are weaned at 9-10 weeks and begin to travel with mothers by late-May. Adult size is often reached by early winter although young may remain associated with their mother, siblings, and the resident male until reproductive maturity (Copeland 1996). Female wolverines attain sexual maturity at about 15 months but only 7% of 2-year-old females produced litters in a Yukon Territory study (Banci 1987). Males appear to reach sexual maturity at about 2 years of age (Banci 1987). Data from Idaho suggest the male may participate in rearing of young (Copeland 1996). Copeland (1996) found that from parturition to physical maturation, at about 8 months of age, the female was the primary associate of young, while from physical maturity until about 14 months of age, juveniles associated primarily with the resident male. Species Account Menu Denning Fennoscandian studies provide the earliest data on winter denning habits of wolverine. Pulliainen (1968) presented the characteristics of 31 reproductive dens in Finland. Eighty-one percent of dens occurred on bare, rocky hillsides of mountain slopes near or above timberline, while 6 dens were located in lower elevation spruce and pine peat-bogs. Most of 28 dens in Norway were situated above timberline in deep snow near cliff areas (Myrberget 1968). The general structure of dens in both studies was the same. Den entrances were located in soft snow near trees or rocks, with a vertical tunnel extending 1-5 meters to ground level. Lateral tunnels extended for up to 50 meters along the ground surface. In most cases, wolverine kits were found at ground level on bare soil. Data on wolverine denning habits in North America are limited. Rausch and Pearson (1972) described 3 dens in Alaska. Two were above timberline in snow filled ravines while the third was found in an abandoned beaver house. Magoun (1985) provided data on the natal dens of 2 females in tundra habitat of northwest Alaska. She described entrance tunnels extending less than 2 meters beneath the snow surface accessing den systems of up to 50 meters in length. The denning habitat used by 2 marked females and 1 unmarked female in Idaho (Copeland 1996) was specific to subalpine talus habitats. Females selected den sites associated with large boulder talus (individual rock size greater than 2 meters diameter) in subalpine cirque basins above 2,500 m elevation. Female wolverines in Idaho accessed natal dens by tunneling through snow into the natural chambers and passage-ways created by the talus. The depth of snow at the time of den use was not determined, but it most likely exceeded 2 meters. The site of parturition could not be identified, although it did not appear to have occurred within the snow layer. Substantial vegetation caches were present in both natal dens, but evidence of use by wolverines was not present (Copeland 1996). In 10 of 28 dens in Norway, young laid on branches while in the remainder of cases they were found on the ground or bare snow (Myrberget 1968). In all reported cases in the Finland study (Pulliainen 1968), kits were found lying on bare ground. All authors agree that use of reproductive dens begins from early February to late March. In some cases, females may use multiple dens prior to kit weaning. Why dens become unsuitable is not well understood. Fennoscandian studies were based on data collected from wolverine hunters rather than radio instrumented animals, so it was not always known if dens were the actual birthing sites. Idaho wolverines abandoned natal dens as early as 10 March, moving kits through a series of maternal dens until weaning which occurred at 9-10 weeks of age (Copeland 1996). Females in arctic Alaska remained at a single den until late April or early May and did not appear disturbed by the presence of human observers (Magoun 1985). Magoun (1985) felt that den abandonment was probably forced by snow melt. Fennoscandian studies report den abandonment as a common response to human disturbance. Finland wolverine hunters emphasized that pursuit of a pregnant female may result in use of "exceptional" places as birthing sites (Pulliainen 1968). Myrberget (1968) mentions 4 instances of den abandonment due to human disturbance and suggests that secondary dens may be less suitable. Direct contact occurred with 2 denning females in Idaho in late April and May and resulted in den abandonment in both cases (Copeland 1996). Ewer (1972) suggests that moves may occur in response to den parasites, or attempts by the female to deter predators from locating the den. Species Account Menu Mortality Aside from human-caused mortality, starvation and predation appear to be primary causes of death in weaned wolverines. Starvation was the suspected cause of death in 2 juvenile wolverines in Yukon (Banci 1987) and 2 in Montana (Hornocker and Hash 1981), although food resources were relatively abundant in both areas. Predation mortality may be exacerbated when wolverines scavenge kills in the presence of other carnivores. The role of more efficient carnivores as producers of carrion may be essential to survival in some areas, but the beneficiary may risk serious injury or death. Where they both coexist, wolves and mountain lions may kill wolverines (Burkholder 1962, Boles 1977, Gill 1978, Hornocker and Hash 1981, Banci 1987, Copeland 1996). The importance of predation on wolverine kits has not been documented (Banci 1994). Wolverine mothers go to great lengths to find secure dens for their young, suggesting that predation may be important (Banci 1994). Species Account Menu Density In general, wolverine densities are low relative to carnivores of similar size, although ranges from 40 km² to 800 km² per wolverine have been reported (Banci 1994). Magoun (1985) in Arctic Alaska and Copeland (1996) in Idaho calculated density based on reproductive potential and home range size for estimates of 1 wolverine/48-139 km², and 1 wolverine/90-113 km² respectively. Hornocker and Hash (1981) and Quick (1953) reported population density estimates of 1 wolverine/65 km² in northwest Montana and 1 wolverine/207 km² in British Columbia, respectively, based on capture and snowtracking data. Banci (1987) estimated Yukon wolverine densities at 1/177 km² based on capture data. Home range estimators may inject bias into a density estimate due to variability in sample size and home range estimation technique, which may preclude comparison to other regions. However, these may be the best estimates available until long-term capture-recapture studies can provide provide precise, empirical estimates. Species Account Menu Spatial Use Home Range Size Six studies provide estimates of wolverine home range use from radio instrumented study animals (Hornocker and Hash 1981, Gardner 1985, Magoun 1985, Whitman et al. 1986, Banci 1987, Copeland 1996). Researchers focused primarily on home range size, stratified by sex and season. These studies also addressed home range overlap to investigate a postulated spacing pattern of intrasexual exclusion. Hatler (1989) noted several commonalities of spatial use for wolverine. Males have larger home ranges than females, females without kits have larger home ranges than accompanied females, and home range use appears to vary with season. Alaska wolverine researchers reported mean annual home range size for male wolverines at 535 km² (Whitman et al. 1986), 637 km² (Gardner 1985) and 666 km² (Magoun 1985), while Montana and Yukon male home ranges were somewhat reduced at 422 km² (Hornocker and Hash 1981) and 382 km² (Banci 1987), respectively. Idaho wolverines displayed the largest spatial requirements with resident male home ranges averaging 1,522 km². Female home ranges varied from 104 km² in Alaska (Magoun 1985) to 388 km² in Montana (Hornocker and Hash 1981), with 1 Montana female using a 963 km² home range. Home range size is generally presumed inversely correlated with the availability of resources following the contention that food controls female dispersion, while the spacing of males is tied to the distribution of females (reviewed in Gittleman and Harvey 1982, Macdonald 1983, Sandell 1989). Food availability was not measured within any of the North American wolverine study areas, and the relationship between resource dispersion and home range size in wolverines is not known. Hornocker and Hash (1981) believed an abundant and consistent ungulate prey base in their study area explained higher estimates of wolverine density than estimates available for wolverine populations at higher latitudes. As ungulates appeared to provide adequate food for Idaho wolverines, defense of feeding sites was not apparent, while sharing of resources appeared common within kinship groups. Long daily movements in Idaho wolverines may reflect a widely dispersed, although not necessarily limited, food resource. Patchy dispersion of resources generally leads to increased home range size (Macdonald 1983) and may also lead to resource competition (Sandell 1989), while highly concentrated food resources may force breakdowns in established territory boundaries, altering the social system and allowing individuals to exploit new opportunities (Lott 1991). Although the latter was not evident in Idaho or Alaska populations, Yukon wolverines concentrated on spawning streams to take advantage of. Gardner (1985) suggested home range size may be related to habitat and topography as well as food availability, while Krott (1959) believed the availability of suitable denning habitat may influence the size of wolverine territories. Idaho wolverines appeared highly selective in choice of natal denning and kit rearing habitat (Copeland 1996). While studies in Alaska and Canada suggested early dispersal of offspring and limited social interaction, subadult wolverines in Idaho remained associated with their natal area until sexual maturity in their second year. Their presence was tolerated by resident adults and resources were commonly shared (Copeland 1996). Large home ranges of Idaho wolverines may reflect the resource requirements of offspring with extended dependency needs in addition to the energetic requirements of the parent (Copeland 1996). Home range size related to reproductive activity Female wolverine accompanied by kits may display reduced home range size. Banci (1987) measured home ranges of 5 accompanied and 5 unaccompanied females and found home ranges of females with young 50% smaller than those of unaccompanied females. A single Idaho female wolverine absent of kits in 1 year displaying a March through August home range nearly 2 times the size of home ranges within the same period in the next 2 successive years when accompanied by kits (Copeland 1996). Home range overlap Intersexual overlap of home ranges is one of the few common aspects of wolverine spatial patterns reported in wolverine studies; the amounts of intrasexual overlap vary considerably. Magoun (1985) and Copeland (1996) found most resident female home ranges were maintained exclusive of other females with spatial separation most prominent during summer months. The other Alaska study (Gardner 1985) only found home range overlap within a single adult and subadult male. Hornocker and Hash (1981) found no evidence of exclusive home range use and suggested that trapping harvest may have created behavioral instability in the population, allowing inadequate time for establishment of site tenure. Hornocker and Hash (1981) and Banci (1987) concluded that a lack of understanding of familial relationships in their wolverine populations made assessment of spatial relationships difficult. Within the home range of a single resident male in Idaho, resident juvenile wolverines remained closely associated to their mother's home range until separation in mid-to-late August of their first year. As subadults, they overlapped the home range of the resident male as well as their mother and siblings. In 2 cases subadults were found associating with a neighboring adult female, and a neighboring adult male. In both instances, the adults were kin to the subadults (Copeland 1996). Association at this early stage of development may suggest a familiarity between the mated wolverine pairs beyond that generally expected within a polygynous species. The dominance status of the resident male may provide him with what Eisenberg (1981) termed a "priority of access" to resident females resulting from established pair bonding, or as Eisenberg (1981:411) suggests, some female "choice" may be involved. A requirement of familiarity for mate pairing might lessen the need for the resident male to defend access to females. Given the extremely large home ranges used by male Idaho wolverines, such a mating strategy would appear more plausible than one based on resource defense or spatial separation of males through scentmarking. Any reduction in mating opportunity may be offset by increased kit survival resulting from male parental investment. Species Account Menu Food Habits Ewer (1973) described the wolverine as a polyphagous mustelid. Wolverines would probably not persist in the absence of ungulate populations, and evidence suggests at least a seasonal reliance on local rodent abundance (Magoun 1985, Gardner 1985, Banci 1987). The wolverine is capable of taking large ungulates as live prey (Myrberget 1968, Pulliainen 1968, Magoun 1985), but ungulate presence in the wolverine diet most likely results from scavenging (Hornocker and Hash 1981, Magoun 1985, Gardner 1985, Banci 1987, Copeland 1996). Ungulate use by wolverines at higher latitudes was more prevalent during months associated with migrating caribou (Rangifer tarandus) or local moose populations (Magoun 1985, Gardner 1985). Ground squirrels were most prevalent in late winter and spring diets in arctic Alaska (Magoun 1985) and southcentral Alaska (Gardner 1985), while snowshoe hare contributed the highest proportion of any single species to the wolverine's diet in Yukon (Banci 1987). Vegetation has been reported in the diet of wolverines, but it may be consumed incidental with prey rather than in lieu of prey (Banci 1987). Species Account Menu Habitat Use Hornocker and Hash (1981) found 70% of wolverine use in medium to scattered timber. Idaho research reported similar results, with montane coniferous forest types accounting for 70.2% of wolverine use (Copeland 1996). Southcentral Alaska wolverines preferred spruce (Piceasp.) during winter and rocky areas during summer (Gardner 1985). Male wolverines in Yukon preferred coniferous habitats in winter and avoided alpine talus in summer (Banci 1987). Whitman et al. (1986) found forest types were avoided by wolverines during summer in south-central Alaska. Preference for higher elevation habitats during summer may be related to the availability of prey (Gardner 1985, Whitman et al. 1986) or human avoidance (Hornocker and Hash 1981) while lower elevational forest types commonly associated with wild ungulates likely provide the highest carrion availability (Copeland 1996). Banci (1985) felt that low rodent availability in subalpine habitats in Yukon may have accounted for avoidance of these areas by male wolverines. Montana wolverines were reluctant to cross openings such as clearcuts or burned areas (Hornocker and Hash 1981). Idaho wolverines commonly crossed natural openings and areas with sparse overstory such as burned areas, meadows, or open mountain-tops (Copeland 1996). Eight Idaho wolverines were relocated in burned areas at least once. Extirpation of the wolverine through the eastern provinces of Canada and the midwestern U.S. most likely coincided with the westward advancement of civilization (Banci 1994). Throughout its North American range, the wolverine occupies a wide variety of habitats, although the character of wolverine habitat most readily apparent is its isolation from the presence and influence of humans. Habitat used by the wolverine, such as vegetative communities that support a prey base and landscape features suitable for denning habitat, may be as useful for their isolation as for their other attributes. Hatler (1989) commented that no particular habitat components can presently be singled out specifically for wolverine and added that reduction of wilderness "refugia", through access and alienation for timber and mineral extraction, may be the greatest threat to local population viability. The wolverine has persisted in southwestern Alberta, despite extirpation elsewhere in the province largely because of the presence of large refugia in the form of National Parks (Banci 1994). The discovery of fossil wolverine remains in cold desert environments of southern Idaho (White et al. 1984) may characterize the species' adaptability. Over harvest and displacement by humans may have forced the wolverine out of lowland habitats now altered by agriculture and urban development, and into the more isolated tracts of its present day distribution. The absence of wolverine from historical ranges may be related to human activity as much as from reductions in habitat. As transient wolverine (usually young dispersing individuals) attempt to colonize or travel through areas of human habitation, their probability of survival may be low. Species Account Menu Management Considerations In the United States, wolverine may be harvested only in Alaska and Montana. Outside of these areas a lack of basic information on wolverine distribution and habitat requirements has resulted in little management beyond administrative protection. Hatler (1989) suggested that appropriately responsive management will require a better knowledge of the nature, extent and correlates of wolverine occurrence. Zielinski and Kucera (1996) argued that distributional surveys are essential to the generation of habitat-relations models in the evaluation of land-use changes and the effects of human density and disturbance. Surveys should focus on determining occurrence and may include snowtracking surveys or remote camera bait surveys (Zielinski and Kucera 1996). Winter aerial surveys of potential denning habitat may provide an alternative to ground methods. Female wolverine in Idaho located reproductive dens on northerly aspects in isolated subalpine talus cirques. These sites generally lacked overstory canopy, allowing snow trails of females traveling to and from the natal den to be visible from aircraft. Protection of natal denning habitat from human disturbance may be critical for the persistence of wolverine. The clear association between wolverine presence and refugia may be strongly linked to a lack of available natal denning habitat outside protected areas. Idaho wolverines selected specific natal and kit rearing habitat and responded negatively to human disturbance near these sites. Technological advances in over-snow vehicles and increased interest in winter recreation has likely displaced wolverines from potential denning habitat and will continue to threaten what may be a limited resource. Vegetative characteristics appear less important to wolverine than physiographic structure of the habitat. Montane coniferous forests, suitable for winter foraging and summer kit rearing, may only be useful if connected with subalpine cirque habitats required for natal denning, security areas, and summer foraging. In addition, these habitats must be available during the proper season. Subalpine cirque areas, important for natal denning, may be made unavailable by winter recreational activities. Conversely, high road densities, timber sales, or housing developments on the fringes of subalpine habitats may reduce potential for winter foraging and kit rearing, and increase the probability of human-caused wolverine mortality. Management practices that reduce carrion may affect wolverine foraging success. A close relationship exists between wolverine and ungulate presence. Ungulate carrion is a primary food item and activities that decrease large mammal populations may negatively affect carrion availability. Excessive hunter harvesting and loss of ungulate wintering areas (Banci 1994), as well as displacement of ungulate populations due to excessive timber harvest and urbanization, may adversely impact wolverines. Wounding mortality of ungulates from hunting and livestock losses on public grazing allotments most likely provides a consistent carrion source. Refugia may be most important in providing availability and protection of reproductive denning habitat. Life history requirements of the wolverine are tied to the presence and stability of ecosystems lacking broad scale human influence. Dispersing wolverines in Idaho traveled over 200 km following routes across isolated subalpine habitat. Habitat alteration may isolate subpopulations, increasing their susceptibility to extinction processes. Return to Management Page

| Home | About TWF | Wolverine Life History | Management | Art | | Current Research | Bibliography | Our Directors | Donations | FAQ's | Kid's Page | Gift Shop |