Diet selection and energy and water budgets of the common spiny mouse Acomys cahivinus

The common spiny mouse, Acomys cahirinus (body mass=47 g), is widely distributed in Israeli deserts where it inhabits natural crevices on rocky slopes. This omnivorous rodent consumes a varied diet, and in particular snails. We determined diet selection and energy and water balances of spiny mice when they were offered snails and seeds. The spiny mice maintained steady state body mass. Dry matter consumption of snails was 0.014 g* g⁻¹.‐d⁻¹ and of seeds was 0.049g*.g⁻¹d⁻¹ for a total of 0.063 g*g⁻¹*d⁻¹. Total water intake was 0.101ml‐g⁻¹.d⁻¹ and metabolizable energy intakewas 0.990 kJ. gxs^‐1.d⁻¹ for a ratio (ml: kJ) of 0.102. This ratio was similar to that reported in a previously published study on free‐living spiny mice. We concluded that snails and seeds allowed spiny mice to fulfil their energy and water requirements with minimal dry matter and fresh matter intakes. Furthermore, spiny mice selected a diet that provided them with a water (ml) to energy (kJ) ratio of approximately 0.1, although it appeared that they are able to survive on a much drier diet.