Effect of ambient temperature on the selection of rest structures by fishers

Abstract

We examined the effect of ambient temperature on the selection of rest structures by 20 radio-tagged fishers in two areas of central British Columbia during 1991-1993 and 1996-2000. Fishers rested in tree cavities, on rust brooms or tree branches, under pieces of large coarse woody debris (CWD), and in burrows or rock crevices. We located fishers at 86 rest structures and recorded the local ambient temperature at nearby climate stations while these structures were occupied. The type of rest structure selected by fishers varied with local ambient temperature (P=0.005). Temperatures were colder when fishers used CWD structures than when they used branch or cavity structures (P<0.05). Large pieces of CWD may be important habitat elements for fishers during long periods of extremely low temperatures because they likely provide a more favorable thermal microenvironment than that found at other types of rest structures. Our results have implications for habitat management and conservation of old-forest structures for fishers in regions with cold climates.