Home range and population density of fishers in eastern Ontario

Fishers (Martes pennanti) were almost extirpated in Ontario, Canada, south of the French and Mattawa rivers by the 1940s but have recolonized much of their former range over the past several decades. We assessed the effect of the current harvest quota on a fisher population in eastern Ontario by estimating home range size and population density from a sample of radiocollared animals. Mean (+/- SD) adult home ranges (based on annual 95% min. convex polygons) were consistently smaller than those reported in the literature (M: 11 +/- 4.4 km(2); F: 2.1 +/- 0.8 km(2)), with up to 71% overlap of adjacent intrasexual home ranges. This yielded an estimated adult fisher population density of 32.7/100 km(2) of suitable habitat, as defined by the habitat composition within observed home ranges. We further estimated that between 2003 and 2005, trappers harvested 17.8-42.3% of the pretrapping population. These results suggest that although current fisher population density is high in our study area compared to reported densities in other areas, harvest rate is also high and an increase in quota is unwarranted.