Data from: Ultradian rhythms of activity in a wild subterranean rodent

Many animals adapt their activity patterns to the best environmental
conditions using diel rhythms. African mole-rats (family Bathyergidae) are
among the mammals that have become models for studying how these rhythms
can be entrained by different cues (light or temperature) in experimental
laboratory studies. However, it is unclear whether they exhibit similar
circadian rhythms in their natural lightless, subterranean environment. In
this study, we used biologging to investigate the activity rhythms of
wild, highveld mole-rats. We show that their activity cycle exhibited an
ultradian rhythm with a length between 4 - 8 hours. On an individual
level, mole-rats displayed about 5 activity bouts per day, occurring at
various times during the day and night. On a population level, activity
peaked in the afternoon, coinciding with the peak in ambient temperature.
Our research suggests that wild subterranean mammals, which experience
constant darkness and reduced environmental variation, are unlikely to
show clear circadian rhythmicity. Instead, activity periods are
distributed over several bouts throughout the day and night and is likely
synchronized to daily temperature cycles. We propose that ultradian
rhythms may be more common than previously thought and discuss how
physiological processes may generate differences in periodicity between
laboratory and wild populations.