Fisher (Pekania pennanti) distribution in riparian forest patches of northeastern North Dakota: habitat plasticity or a short-term aberration?

Posted on Nov 30, 2020


by Maggie D. TRISKA, Steven L. LOUGHRY, and Thomas L. SERFASS
CWBM 9 (2): 68-80.

Correspondence: Maggie D. Triska, Round River Conservation Studies, 104 East Main Street, Bozeman, Montana, 59718, USA.



Fishers (Pekania pennanti) are a forest carnivore that was widely distributed throughout Canada and the northern United States of America. However, their populations were greatly reduced during the 19th and 20th centuries following habitat loss and unregulated trapping. Studies that established fisher habitat associations with dense forest and undergrowth connected to old-growth forest were completed on these remnant populations, contributing to generalized habitat paradigms that are potentially biased because they are based on habitat conditions within the range occupied by the remnant populations and not the totality of conditions within the historic range of the fisher. More recently, fisher populations have begun expanding naturally and through reintroduction efforts. Although these populations persist within the historic range of the fisher, they often occupy habitats that do not appear to fit accepted habitat paradigms for the species (e.g., occurrence in deciduous and/or patchy forests). Our study focused on a fisher population in North Dakota (ND) occupying forested, riparian patches, and presumed to have initially colonized the northeastern region of the state since 1999. We summarized verified fisher sightings collected by the North Dakota Game and Fish Department from 1999 through 2019 to assess fisher distribution over time. During the summer of 2009, we used remote cameras placed in riparian-forest patches distributed throughout northeastern ND to compare aspects of size and spatial distribution among forested patches where fishers were and were not detected. Based on existing habitat paradigms, we hypothesized fishers occupying the area would occur most frequently in larger, more proximate forest patches of the riparian forest. However, neither forest patch size nor proximity contributed to explaining the patterns of fisher detections. Furthermore, we evaluated latency to detection (as the number of days until detection) and determined that fishers were detected quicker in small patches (1-50 ha) than medium (>50-250 ha) and large (>250 ha) forest patches, an outcome implying that fishers are more likely to encounter a camera in a small patch than larger patches leading to fewer days until detection. The lack of support for our hypothesis that fisher habitat associations would reflect historic paradigms provides evidence for fisher habitat plasticity and their potential ability to expand and persist in habitats not reflected by historic habitat paradigms.

Key Words: Fisher, Habitat Associations, Habitat Paradigms, Linear Forest, Mustelidae, Natural Recolonization, North Dakota, Pekania pennanti.

3 - Triska et al


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