Abundance and Distribution of Wolverine in the Kootenay Region

The specie Wolverine is under conservation provincially and nationally. Unfortunately, there is a lack of verification about how many wolverine live in the province, including the southern part of the Kootenays. It is known that U.S. populations are on a critical low level and therefore it is crucial for species conservation in the region. There is genetic evidence that population fragmentation is increasing in the north and south of B.C., even though the extent of gene flow between neighbouring ranges in the southern Kootenay region is unknown. There are some barricades to dispersal properly like transportation routes or land use changes. Secondly, the use of winter activities is associated negatively with wolverine population but positively with roadless areas.  The Kootenay region is one of the only few areas know as a corridor for transboundary species. Such movements are really significant for the U.S. populations and it will provide crucial information for wolverine conservation in this region.

Methods

Field surveys

The southern study area was partitioned into 10 by 10 km cells, one is around the size of a home range. These 65 quadrats were sampled twice in 21 days. Hair trap sites were created by affixing a bait item to a tree around two meters from the ground to entice the animal to climb.  The bait was nailed to the tree and wrapped in wire. Every time it was checked hairs were collected and if necessary, the bait was replenished. During the first and the second season six cameras were used. Trappers were also asked to hand over some genetic samples.

Genetic Analysis

Hair samples were submitted to Wildlife Genetics International in Nelson B.C for a DNA analysis.

Occupancy and abundance

The single-season model program PRESENCE was used to estimate the proportion of sample stations occupied by wolverine. If there was a non-detection this could have meant that the wolverine were not present at the site or it was just failed to detect an individual when it was present. To estimate the probability of missing species, observations are repeated over a period of time during which site occupancy is assumed to be constant. A non-detection can be treated as a false negative if there is at least one detection. A home range of a female wolverine is around 10 by 10km minimum. However, the average home range size in the Columbia Mountains was 300 km2 and 1000km2 for female and overlapping male wolverine. There is a simple method called Lincoln-Peterson which is used to estimate the population independent of occupancy.

Population genetics

A program called POPULATIONS  calculates shared allele distances. This is a simple measure of the degree of relatedness between individual genotypes in our samples.

Results

Field surveys

During the whole process they installed 65 sites in the Purcells, three in the Nelson and Bonnington ranges. They collected 24,537 pictures over 9,476 hours. They detected wolverine, squirrel, coyote and mouse during the review.

Genetic analysis

They obtained results from 356 hair, tissue, scat and skull samples. The Wolverine DNA was detected at 10 sites. From those 10 sites they were able to identify 8 female wolverines. In 2013 ten wolverine carcasses were submitted by the trappers, whereas in 2012 only 4 were submitted. One of these carcasses was a female that was used for a study in the Flathead River in 2012. She was trapped outside the south Purcell study area in 2013 after travelling a distance of about 100 km

Occupancy and abundance

After some calculations with different methods the occupancy-based population estimate was 17 wolverine for the south Purcell population.

Population genetics

Visual inspection of the neighbour-joining tree shows 10 of 11 wolverines from the south Purcells clustered on the same branch and the three from the central Selkirk Mountains clustered together as well. Three of four south Selkirk wolverines share the same branch. Individual  populations do not appear to be clustered geographically.

Discussion

This research represents the first on the ground attempt to inventory wolverine populations in the southern Kootenay region. Different analysis of wolverine habitat in B.C rated most of the southern Purcells as high quality habitat whereas the southern Selkirks are moderate. They expected a larger contiguous area in the southern Purcell and in the Selkirks but they found the opposite. Factors were related to harvest, forest management, prey abundance and habitat fragmentation. The Selkirks have a higher proportion of in land in protected areas but the access to arrive there is very difficult.

The estimate of occupancy is around 17 wolverine based on average home range sizes. This estimate is below the published one estimate of population size for the south Purcells: 27.

Female productivity is strongly linked to their body condition and hence food availability. Consequently recruitment might be greater in unusually productive environments. However, a high rate in the south Purcells might also explain the large number of females in our genetics sample. Males have larger home ranges and are found at lower elevations.

The project is beginning to fill a knowledge gap for a species that is a conservation priority in the U.S.,  and Canada. This information is vital for identifying viable movement linkages and protecting habitat.

Wolverine in:

  • Source Andrea Kortello, Doris Hausleitner. February 2014. Abundance and Distribution of Wolverine in the Kootenay Region 2013 Field Season Report: Purcell Mountains. Prepared by Seepanee Ecological Consulting, for the Ministry of Forests Lands and Natural Resource Operations and Columbia Basin Trust . Available at : http://wolverinefoundation.org/wp-content/uploads/2014/03/Kootenay-Wolverine-Project-2013_final-report.pdf [Accessed 03/2021].