ACTIVITY PATTERNS, MOVEMENTS, AND REPRODUCTIVE ECOLOGY OF FISHERS IN SOUTH-CENTRAL MAINE

Most activity of adult fishers (Martes pennanti) occurred shortly before sunrise and after sunset, but some activity occurred throughout the day and night. Males and females showed similar amounts of activity, and both were active more frequently in summer than winter. Movements of males were greatest during the spring breeding season; nonreproductive females moved similar distances during all seasons. Eleven maternal dens were in tree cavities; the denning period lasted 8-12 weeks from March through May. The maximum annual parturition rate among females greater-than-or-equal-to 2 years old was 75% (n = 4). This was less than pregnancy rates indicated by corpora lutea, and suggested that some pregnancies were unsuccessful. We hypothesize that delayed implantation allows mating to occur at a favorable time for adults, and births to occur when offspring have the maximum time for development before winter.