Differential Footload of Male and Female Fisher, <em>Martes pennanti</em>, in Quebec

Abstract

We examined the mass, foot area and foot load (mass/surface area) of Fishers (Carnivora: Mustelidae: Martes pennanti) captured during the 2006-2007 commercial fur season in southern Quebec, Canada. Body mass of males (mean = 4.7 kg ± 0.5, n = 37) was significantly larger than that of females (mean = 2.4 kg ± 0.2, n = 40). Similarly, the size of male feet (mean area = 130.5 cm2 ± 10.9, n = 37) was significantly larger than that of females (mean = 95.2 cm2 ± 7.6 SE, n = 40). The resulting footload of males (36.2 g/cm2 ± 6.1, n = 37) was 43% larger than that of females (25.3 g/cm2 ± 2.3, n = 40). These results may help explain the differential behaviour and niche partitioning in this mustelid carnivore.

Sex and age mediate the effects of rapid environmental change for a forest carnivore, the Fisher (Pekania pennanti)

“…Indeed, while modest snowfall at regular intervals typically creates dense compacted snow, periods of heavy snowfall can create areas of deep, fluffy snow that limit occupancy and dispersal of many carnivore species (Pozzanghera et al 2016). Among fishers, high foot loading is theorized to compound the energetic cost of movement through deep snow (Pauli et al 2022), and male fishers exhibit a foot load up to 43% greater than females (Renard et al 2008). However, while increasing snow depth had a negative effect on female survival, male survival was unaffected-which ran counter to our predictions.…”

“…Although fishers would have historically existed in a landscape with diverse topography and land cover (including natural openings and constrictions in forest cover), under current conditions there is concern that geographic barriers and habitat fragmentation may restrict connectivity and spatial recovery (Tucker et al 2014; Thompson et al 2021a), while mortalities from predation, disease, and anthropogenic threats including toxicants, incidental trapping, and vehicle collisions could limit population growth (Sweitzer et al 2016a; Lewis et al 2022). Fishers also possess relatively high foot loadings that can constrain movement in deep, uncompacted snow (Renard et al 2008; Suffice et al 2020), which exerts an energetic cost limiting occupancy and dispersal (Pauli et al 2022). Fishers in this region have a complex history of dietary constraints; while fishers typically consume large-bodied Snowshoe Hare ( Lepus americanus ) and Porcupine ( Erethizon dorsatum ) across much of their distributional range (Kirby et al 2018; Pauli et al 2022), Fisher diet in the southern Sierra Nevada is primarily limited to small mammals (e.g.…”

“…Second, we predicted that survival would decrease with increasing drought severity and forest mortality. We also predicted that survival would decrease with increasing snow depth (Suffice et al 2020; Pauli et al 2022), and that this effect would be stronger for males as larger body size, home range, and foot loading impose greater energetic costs (Renard et al 2008). Finally, we predicted that increasing consumption of atypical foods, especially the consumption of fungi, would decrease survival for both males and females (Green et al 2018; Kirby et al 2018).…”

Winter and summer weather modulate the demography of wild turkeys at the northern edge of the species distribution

“…Across much of the northern hemisphere where winter precipitation occurs as snow, global warming is predicted to decrease frequency (Krasting et al 2013) but increase severity of snowfall (Chaumont and Brown 2010). Deep snow has various efects on northern animal species as it may impose thermoregulation constraints (Janke et al 2015), impede movements (Crête and Larivière 2003;Renard et al 2008) and foraging (Johnson et al 2001). Southern species moving north may not yet have the necessary adaptations to cope with deep snow (Telfer and Kelsall 1984).…”

Classifying carnivore tracks using dimensions that control for snow conditions

“…Fisher feet are not fur‐covered or as large relative to their size and mass. As a result, fisher foot‐loading is ≥2 times greater than for martens (Krohn et al , Renard et al ). Adult females are smaller than adult males in both species; both sexes of adult marten are smaller than both sexes of adult fisher (Powell et al ).…”