Human caused mortality in the endangered Scandinavian wolverine population

The wolverine is a relatively long lived mustelid species with low average annual reproduction which in theory makes them sensitive to changes in survival rates. In a multi-year study we monitored 211 radio-marked wolverines to estimate age-specific survival rates and mortality causes in an endangered population. Our data suggests that poaching forms a substantial part of wolverine population dynamics in northern Scandinavia causing up to 60% of adult mortality. Average annual adult survival rate was 0.91. Male and female survival rates did not differ. Twenty-five adult wolverines were confirmed to have died during the study. Fifty-two percent of confirmed adult mortality was human caused. The most important cause of adult mortality was poaching (9). Annual adult survival was lower (0.86) when 15 adult resident wolverines that were assumed to have died due to poaching were included in the analyses. Natural mortality among subadults and adults was less frequent in our study population compared to North American wolverine populations. Adult survival was significantly lower during the snow season (December–May) than during the snow-free season (June–November), while natural mortality was more evenly distributed between seasons. We explain this by the frequency of poaching which is higher during snow season. Our results underline the need to frame the underlying human dimension factors behind poaching to facilitate conservation and management of endangered populations.