Habitat response to grazing: Different abilities of rodent species to use feces as a water source

An analysis of grazing impact of mountain goat (Capra aegraris) on a post-fire habitat revealed effects in the rodent-community composition. The dominant rodent species in the grazed plots was the common spiny mouse, Acomys cahirinus, whereas in the non-grazed plots, two wood-mice species, Apodemus mystacinus and A. flavicollis, were most abundant. The aim of this study was to test if goat feces give an advantage to A. cahirinus. Six individuals of each species were kept on a dry diet and moisture was available only from goat feces. The loss of body mass over time was measured. When A. cahirinus were offered rat pellets and goat feces, they lost on average 13.6% of their initial body mass after five days. Under the same conditions, the mean loss of A. mystacinus was 25.5% (p < 0.001). In a following experiment, A. cahirinus were given soybeans as a dehydration-enhancing food source and wet goat feces as a water source. After subjects lost significant body mass, the soybeans were replaced with dry rat-pellets, while goat feces remained the only water source. Subjects rapidly recovered body mass under these conditions. These results suggest goat feces may provide a sufficient source of moisture for A. cahirinus, but not for A. mystacinus. Hence, goat grazing may produce suitable conditions for A. cahirinus.