Data for 'Variation in soil temperature predicts small seasonal shifts in daily activity patterns of a social subterranean rodent'

Animals often show distinct activity rhythms which may align their behaviour with favourable environmental conditions. In terrestrial species, daily and seasonal activity patterns are largely influenced by changes in photoperiod and temperature. However, subterranean animals experience weak or absent environmental variation due to minimal light exposure and reduced daily temperature fluctuations. Despite these conditions, many subterranean rodents display pronounced diel rhythms in physiological processes and locomotor activity, though the extent of seasonal variation remains unclear. In this study, we show that wild groups of subterranean Damaraland mole-rats exhibit a population-wide daily activity peak around midday. The timing of this peak shifts by approximately two hours between seasons and coincides with temperature minima at 40 cm depth. Neither individual nor group characteristics predict its occurrence and timing, suggesting that temperature fluctuations, rather than social factors, are the main driver of seasonal variation in activity timing. Although Damaraland mole-rats remain active at low levels throughout the day, they display clear diurnal foraging rhythms at the group level that change little across seasons.
We utilized an RFID reader array (LID650/608, DorsetID, The Netherlands) to monitor mole-rat activity for a full calendar year. Mole-rats wree implanted with a subcutaneous transponder and released into their burrow. Animals were weighed, sexed, and assigned a reproductive class upon capture. The array was programed to scan continuously for transponder tags within range with a read delay of 3 seconds and save transponder codes with a time stamp. Thus, if an animal remained in the range of the panel for longer than 3 seconds, it would have multiple entries at 3-second intervals. The reader would then store the transponder code and the date and time. We assumed activity bouts lasted for 1 hour and animals were given an active score of 1 if a reading was detected on the array during a 60-minute period, and a score of 0 if not detected. An animal would not gain a further activity point until detected beyond the activity period. Individuals captured in the group but not recorded by the RFID reader array were assigned activity scores of zero.
We modelled activity using sine-cosine waves and tested for effects of temperature, reproductive status, group size, sex, and body mass on the peak of activity. Here we present the data and R code to reproduce the results of our study.