Temporal partitioning among diurnally and nocturnally active desert spiny mice: energy and water turnover costs

Nocturnal Acomys cahirinus and diurnally active A. russatus coexist in hot rocky deserts. Diurnal and nocturnal activity exposes them to different cli matic challenges. A doubly-labelled water field study revealed no significa nt differences in water turnover between the species at all seasons, reflec ting the adaptations of A. russatus to water conservation. In summers the e nergy expenditure of A. russatus tended to be higher than that of A. cahiri nus. Energy requirements of A. cahirinus in winter are double than that of A. russatus, and may reflect the cost of thermoregulating during cold night s. (C) 2001 Elsevier Science Ltd. All rights reserved.