Factors affecting the duration of activity by pine martens (Martes martes)in the Bialowieza National Park, Poland

The duration of activity bouts by pine martens Martes martes was studied in the pristine deciduous forests in Bialowieza National Park (north-eastern Poland). From 1991 to 1996, 14 martens were monitored by radio-tracking thr oughout 5823 h. On average, male martens were active for 9 h/day and female s for 8.5 h/day. The duration of the martens' diel activity varied greatly among bimonthly periods (from 2.8 h/day in February-March to 12 h/day in Ju ne-July). Martens decreased their activity from 13 h/day on warm days to 2. 5 h/day on cooler days. In the winter months, when martens curtailed their activity, they often hunted larger prey or scavenged ungulate carcasses. On average, 69% of the martens' active time was during the night. The number of activity bouts per day varied from one to six (mean 2.6) and increased w ith growing ambient temperature. Activity bouts of males were significantly longer (4 h, on average) than those of females (3 h) and were not related to ambient temperature. The duration of short inactive bouts increased in t he cold season and inactivity lasted longer in females than in males.