Basking is affected by season and influences oxygen consumption in desert-living striped mice

Abstract

Small mammals that inhabit arid and temporally unproductive environments use several methods to conserve energy. Here we investigate the energetic role of sun basking in striped mice (Rhabdomys pumilio) from the Succulent Karoo desert in South Africa. We observed mice in front of their nests for 140 h and recorded the time they spent basking during the dry (non-breeding) and wet (breeding) season. We measured temperature changes in model mice to provide an indication of the heat that can be absorbed from the sun. Lastly, we measured oxygen consumption () of mice at their basking sites in the field both in the sun and in the shade. This was accomplished using a portable respirometry system with a metabolism chamber that could be placed into and out of the sun. Observations showed that mice basked more often during the non-breeding than the breeding season. During this time, mice spent an average of 11.9 ±1.1
min (SE) in the morning and 5.5 ±0.5 min in the afternoon per day basking (maximum 96 min). Within the metabolism chamber decreased when the animal was in sunshine compared to the shade. This effect occurred independently of ambient temperature (Ta) indicating that a significant amount of radiant energy was absorbed from the sun. Basking may be an alternative to other energy-acquisition behaviours (such as foraging), which might be particularly useful at times when food is scarce.