Daily range sizes correlate positively with resting metabolic rate in bush Karoo rats (Otomys unisulcatus)

Abstract Home range size limits the number of resources an individual can access; hence, it often increases with energy demands. However, maintaining a large home range also requires more energy expenditure, and foraging over a larger area can decrease search efficiency, especially for central place foragers that travel frequently between a home base and food patches. Consequently, individuals may need to reduce energy expenditure in other aspects, such as resting metabolic rate (RMR). So far, studies examining the relationship between home range size and RMR are limited. In this study, we investigated whether RMR is correlated with home range size in bush Karoo rats (Otomys unisulcatus). Using the Foxbox and mini-GPS dataloggers, we measured body mass, RMR (scaled by body mass), and daily home ranges of 25 female adult bush Karoo rats in the field. As commonly found in home range studies, body mass was associated with range size in bush Karoo rats. In addition, body mass-scaled RMR was positively associated with home range size. This suggests that a larger home range provides sufficient energy to support the increased energy expenditure required for foraging, as well as a higher energy budget for basal biological processes in female bush Karoo rats.