Seasonal and sexual variation in diel activity rhythms of pine marten Martes martes in the Bialowieza National Park (Poland)

From 1991-1996, the activity rhythms of 14 radio-collared pine martens Mart es martes (Linnaeus, 1758) (6 males and 8 females) were studied in the pris tine deciduous and mixed forests of the Bialowieza National Park. Tracking data (5823 h) indicated that the activity rhythms of pine martens varied be tween sexes and seasons. In spring, male activity peaked at 20.00-00.00 h, whereas in summer and autumn-winter, activity was bimodal, peaking at 18.00 -22.00 h and 02.00-04.00 h. Female activity in spring was more evenly distr ibuted than that of males, but in summer their activity peaked at 20.00-00. 00 h, while in autumn-winter females had a bimodal rhythm with peaks at 18. 00-20.00 h and 02.00-06.00 h. In breeding females, activity rhythms changed in the course of pregnancy and nursing. On average, martens started their activity 73 +/- 209 (SD) min before sunset and finished 87 +/- 245 min afte r sunrise. Females became active earlier than males but both sexes terminat ed activity at the same time. For both males and females the daily activity rhythm was not related to the diurnal course of temperature.