There is a lack of information about behaviour of strictly subterranean mammals in their natural environments.In our study,we analysed the circadian and spatial activity of an eusocial subterranean rodent,the Ansells mole-rat (Fukomys anselli) in miombo woodland in Zambia.For this purpose,we radio-tracked 17 adults from five free-living families.We tested if: a) the circadian activity of mole-rats is related to environmental factors such as light and soil temperature and b) there exist real discontinuities in the amount of the spatial activity (work) carried out by particular family members in this species (behavioural polyethism) .Contrary to previous laboratory results,we found that the Ansells mole-rats circadian rhythms are closely related to the diurnal course of soil temperature present at a depth of foraging burrows.Interestingly,mole-rats were most active during the hottest part of the day.Breeding males and large non-breeders tended to spend more time inside a nest.Both groups also had smaller home-ranges than smaller non-breeders.Breeding males were not less active than similarly sized non-breeders,but they were active mainly close to the nest.In non-breeders,the effect of sex on the spatial activity was negligible,except long distance journeys (>48 m) ,which were undertaken mostly by females.The largest part of the variability in spatial activity patterns was explained by the group affiliation.After removing its effect,there was no apparent discontinuity in the activity patterns.