Home Range Size
Wolverine home range size varies considerably within and among studies. In general, male home ranges are several times larger than female home ranges. The mean home range size for male wolverines in different areas varies from 422-1,506 km² (Magoun 1985, Whitman et al. 1986, Copeland 1996, Landa et al. 1998, Persson et al. 2010). Mean home range size for female wolverines varies from 73-335 km² (Bjärvall 1982, Magoun 1985, Whitman et al. 1986, Copeland 1996, Landa et al. 1998, Persson et al. 2010). The difference in size between male and female home ranges corresponds with their polygamous mating system where one male breeds with several females (Hedmark et al. 2007). Female home range size in a high-density wolverine population in northern Sweden was similar in years with and without offspring (Persson et al. 2010). However, other studies have suggested that females without offspring have larger home ranges than those of accompanied females (Banci 1987, Copeland 1996).
Home range size is generally presumed to be inversely correlated with the availability of resources following the hypothesis that female home range size is determined by food availability, while the spacing of males is tied to the distribution of females (Sandell 1989). However, the relationship between resource dispersion and home range size of wolverines has yet to be confirmed. Gardner (1985) suggested that home range size might be related to habitat and topography as well as food availability, while Krott (1959) believed that the availability of suitable denning habitat might influence the size of wolverine home ranges.
Home Range Overlap
In general, wolverines exhibit intrasexual territoriality with limited overlap between individuals of the same sex (Magoun 1985, Copeland 1996, Persson et al. 2010).
Occasional overlap between wolverines of the same sex has been explained by intrasexual tolerance and kinship (Persson et al. 2010), or behavioral instability in the population (Hornocker and Hash 1981). Wolverines are assumed to keep home ranges separated in space and time by marking the boundaries with scent, urine, and excrements (Koehler et al. 1980). In addition, direct aggression presumably plays an important role in maintaining exclusive territories. Juvenile and adult females are sometimes killed by conspecifics (Persson et al. 2009). Persson et al. (2003) suggested that unrelated territorial females killed four juvenile females as they left their maternal home ranges in August and September. Furthermore, adult males frequently exhibit fresh scars and wounds during the mating season (Magoun 1985; Wedholm 2006), and intraspecific mortality among sub-adult and adult males have been documented during the mating season (Lofroth 2001; Persson et al. 2009), which suggests that males become aggressive and intolerant of intruders during the mating season. Hence, assuming that intraspecific strife primarily involves individuals of the same sex, it suggests that both male and female wolverines use aggression to defend their territories.
A study of a high-density wolverine population in northern Sweden showed that female wolverines exhibit high inter-annual fidelity to territory as a vast majority of resident females maintained the same territory between years. Aronsson (2009) also showed that new females quickly replaced resident females that died. Moreover, a high proportion of the replacers were closely related to the resident female that died. Aronsson (2009) suggests that the spatial organization of female wolverine territories in a high-density population is characterized by long-term stability, as vacated territories are generally occupied by new individuals rather than absorbed by neighbors.
Dispersal
Age at dispersal seems to be similar for male and female wolverines. Mean dispersal age was 13 months for both male and female wolverines in northern Scandinavia (Vangen et al. 2001), where females displayed more variation in dispersal age (7–26 months) than males (7–18 months). However, Copeland (1996) documented dispersal by two males that were believed to be, or confirmed as 2 years old. A greater proportion of males than females disperse (Banci 1994, Vangen et al. 2001). In Scandinavia, 100% of males and 69% of females dispersed (Vangen et al. 2001). Vangen et al. (2001) suggested that competition for resources determine female dispersal pattern, and that competition for mates explain the male dispersal pattern. Female dispersal frequency seems dependent on the availability of vacant territories (Vangen et al. 2001, Aronsson 2009), i.e. no females disperse from a territory vacated by their mother. Dispersal is often preceded by exploratory movements.
Both male and female wolverines can disperse long distances. Copeland (1996) reported two males dispersing 168 and 199 km, Gardner (1985) relocated a male 378 km from where it was radio-collared, Vangen et al. (2001) reported a female dispersing 178 km, and dispersing individuals in northwestern Alaska may have travelled as far as 300 km (Magoun 1985). Flagstad et al. (2004) used distances between assigned offspring and their mother (based on DNA extraction from sampled scats) to indirectly estimate dispersal distances and found that dispersal distance and variance was larger for males (mean ± SE = 164 ± 64 km) than for females (mean ± SE = 78 ± 18 km). They also documented that two males dispersed 303 and 496 km.
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Literature Cited:
Aronsson, M. 2009. Territorial dynamics of female wolverines. M.Sc. thesis. Swedish University of Agricultural Sciences, Uppsala, Sweden.
Banci, V. 1987. Ecology and behavior of wolverine in Yukon. M.Sc. thesis, Simon Fraser University, Burnaby, Canada.
Bjärvall, A. 1982. A study of the wolverine female during the denning period. Transactions of the International Congress of Game Biologists 14:315–322.
Copeland, J.P. 1996. Biology of the wolverine in central Idaho. M.Sc. thesis, University of Idaho, Moscow, USA.
Flagstad, Ø., E. Hedmark, A. Landa, H. Brøseth, J. Persson, R. Andersen, P. Segerström, and H. Ellegren. 2004. Colonization history and non- invasive monitoring of a re-established wolverine population. Conservation Biology 18:1–13.
Gardner, C.L. 1985. The ecology of wolverines in southcentral Alaska. MSc thesis, University of Alaska, Fairbanks.
Hedmark E., Persson J., Segerström P., Landa A. & Ellegren, H. 2007. Paternity and mating system in wolverines Gulo gulo. Wildlife Biology 13(Suppl 2):13–30.
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Magoun, A.J. 1985. Population characteristics, ecology and management of wolverines in northwestern Alaska. Ph.D. dissertation, University of Alaska, Fairbanks, USA.
Persson, J., P. Wedholm, and P. Segerström. 2010. Space use and territoriality of wolverines (Gulo gulo) in northern Scandinavia. European Journal of Wildlife Research 56(19): 49-57.
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Persson, J., T. Willebrand, A. Landa, R. Andersen and P. Segerström. 2003. The role of intraspecific predation in the survival of juvenile wolverines Gulo gulo. Wildlife Biology 9: 21-28.
Sandell, M. 1989. The mating tactics and spacing patterns of solitary carnivores. In: Gittleman JL (ed) Carnivore Behavior, Ecology and Evolution. Cornell University Press, New York, pp 164–182.
Vangen, K.M., J. Persson, A. Landa, R. Andersen, and P. Segerström. 2001. Characteristics of dispersal in wolverines. Canadian Journal of Zoology 79:1641–1649.
Wedholm, P. 2006. Territoriality and social organization in Scandinavian wolverines Gulo gulo. M.Sc. thesis, Swedish University of Agricultural Sciences, Umeå, Sweden.
Whitman, J.S,, W.B. Ballard, and C.L. Gardner 1986. Home range and habitat use by wolverines in south central Alaska. Journal of Wildlife Management 50:460–463.
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