Daily Energy Expenditure and Water Flux of Free-Living Blanford's Foxes (Vulpes cana), a small Desert Carnivore

1. The Blanford's fox, Vulpes cana (Blanford 1877) is a small canid (mean body mass = 956 g) that inhabits rocky mountains and canyons in the deserts of Israel, where it feeds mainly on invertebrates and fruits. 2. We hypothesized that the energy expenditure of Blanford's foxes would be higher than that of a small canid that inhabits flat terrain, all else being equal. To test this hypothesis, we measured daily energy expenditure and water intake of free-living Blanford's foxes and compared the results with those of the kit fox, Vulpes macrotis (Say 1823). We also estimated dietary intake and seasonal activity periods. 3. Blanford's foxes maintained water and energy balances on a diet of invertebrates and fruits without the need to drink. Metabolism during activity was 8.4 times higher than at rest, and daily energy expenditure of Blanford's foxes was, on average, 30.1% higher than that of the kit fox. This result was compatible with our prediction that activity is more energetically expensive for Blanford's foxes in their mountainous habitat than in another desert fox species that inhabits flat terrains.