Water intake in two coexisting desert rodents, Acomys cahirinus and Gerbillus dasyurus

The common spiny mouse Acomys cahirinus (average body mass 48 g), and Wagner's gerbil Gerbillus dasyurus (33 g), are omnivorous rodents that coexist in rocky habitats in the deserts of Israel. A. cahirinus consumes proportionately more snails and animal matter, and G. dasyurus consumes proportionately more seeds. Rodents were offered seeds and either water ad lib., 50% of ad lib. total water intake, or denied water. Both species were able to maintain steady state body mass on both ad lib. and 50% ad lib. water. Both species lost body mass when denied water, but the daily rate of loss in G. dasyurus was slower than that of A. cahirinus both in absolute (0.72 and 1.72 g) and in relative (10.9 and 2l.9% body mass/g^0.54) terms. Dry matter digestibility and metabolizable energy from seeds were similar between species on the ad lib. and 50% ad lib. water treatments and both species combined averaged 90.9% of dry matter and 88.8% of gross energy, respectively. -from Authors