The daily cycle of activity in the mole (Talpa europaea) and its seasonal changes, as revealed by radioactive monitoring of the nest
Published information on the activity rhythm of the mole (Talpa europaea), although limited to observations on a very few moles during February-April, had indicated a basic short-term cycle of approximately 8 hours. The technique used, manual tracking of radioactively tagged individuals with portable monitors, was modified for the present study to record automatically the presence or absence of the tagged mole at its nest site. Data were obtained for all months of the year, with a total of 797 days of records from 14 male and 13 female animals. The most characteristic feature of the records, irrespective of the time of year and thus daylength, was the sharpness of the transition from inactivity to activity at dawn and the reverse shortly prior to dusk. During midwinter, when daylength was short the animals tended to be active throughout the day, with few or no rest periods at the nest, and there was only one other active period, during the night. With increasing daylength there was usually a short rest period about midday so that the animals had the classical 3-cycle daily rhythm. In summer, with the longest days and shortest nights the timing of the daytime rest period was variable and there was often no active period during the night so that the short-term cycles were less distinct.