The Sustainability of Wolverine Trapping Mortality in Southern Canada

Abstract

Range declines, habitat connectivity, and trapping have created conservation concern for wolverines throughout their range in North America. Previous researchers used population models and observed estimates of survival and reproduction to infer that current trapping rates limit population growth, except perhaps in the far north where trapping rates are lower. Assessing the sustainability of trapping requires demographic and abundance data that are expensive to acquire and are therefore usually only achievable for small populations, which makes generalization risky. We surveyed wolverines over a large area of southern British Columbia and Alberta, Canada, used spatial capture-recapture models to estimate density, and calculated trapping kill rates using provincial fur harvest data. Wolverine density averaged 2 wolverines/1,000 km 2 and was positively related to spring snow cover and negatively related to road density. Observed annual trapping mortality was >8.4%/year. This level of mortality is unlikely to be sustainable except in rare cases where movement rates are high among sub-populations and sizable untrapped refuges exist. Our results suggest wolverine trapping is not sustainable because our study area was fragmented by human and natural barriers and few large refuges existed. We recommend future wolverine trapping mortality be reduced by ≥50% throughout southern British Columbia and Alberta to promote population recovery.

Integrating dead recoveries in open‐population spatial capture–recapture models

“…1). The value of 30 km was chosen to be approximately 3σ of male wolverines based on the literature (Bischof et al 2020 a , Mowat et al 2020) and preliminary analyses.…”

Wolverines (Gulo gulo) in the Arctic: Revisiting distribution and identifying research and conservation priorities amid rapid environmental change

“…The habitat in these regions is superficially similar; all are within roughly 200 km of the latitudinal treeline, fall within the migration paths of substantial caribou herds, and have similar assemblages of potential prey species. Although some of the difference is likely attributable to bias associated with the analytical approaches (Mowat et al 2020 ), this may not explain the entire discrepancy, since the territory sizes of radio-collared individuals studied contemporarily are consistent with the densities, i.e., much smaller in the Utukok region than the Toolik region (Magoun 1985 , Glass unpublished data ). The disparate estimates preclude a generalizable assessment of population density in Low Arctic tundra and highlight the need for additional studies, ideally accounting for spatial and temporal fluctuations in carrion availability, alternative food sources, and wolverine mortality, which can affect density and territorial dynamics of at least reproductive female wolverines (Aronsson and Persson 2018 ).…”

“…In concert with these efforts, we recommend developing community-based reporting initiatives to more accurately document harvest, including demographic information, such as sex and age, as are currently implemented in Arctic Canada (Lee 1994 , 2016 ; Awan and Szor 2012 ; Kukka and Jung 2016 ). Such information can supplement population abundance estimates, enabling study of harvest influences on population dynamics (Mowat et al 2020 ).…”

Protection status, human disturbance, snow cover and trapping drive density of a declining wolverine population in the Canadian Rocky Mountains

“…Wolverines ( Gulo gulo ) are circumboreal apex predators with large home ranges, extremely low densities and slow life histories 25 , which have undergone extensive range contractions worldwide but remained little studied until relatively recently (reviewed in Fisher et al 26 ). Conservation risks include but are not limited to vulnerability to overharvest 27 , 28 , habitat loss 29 , and disturbances from recreation 30 . Due to their high detectability at baited stations and their unique fur markings, wolverines are well-suited for non-invasive DNA and remote camera monitoring techniques 31 , 32 .…”