Influence of habitat structure and food quality on foraging behavior of spiny mice (genus Acomys)

The influence of habitat structure and food quality on foraging microhabitat choice and efficiency of coexisting Acomys cahirinus and A. russatus at En Gedi was studied by using giving-up densities (GUDs) in under-boulder, between-boulders, and open area microhabitats. Artificial foraging patches containing either millet or broken sunflower seeds were used. Both species had lower GUDs for sunflower than for millet, but showed no significant difference in number of trays foraged between seed types. Acomys cahirinus foraged a similar number of trays in each microhabitat, whereas A. russatus preferred the boulder microhabitats. Acomys cahirinus had lower GUDs in the boulder microhabitats than in the open; with sunflower seeds it did not discriminate between the boulder microhabitats, and with millet it did not discriminate between them and the open area. Acomys russatus foraged to lower GUDs in the boulder microhabitats, and attained the lowest GUDs in the under-boulder microhabitat. Acomys russatus was the more efficient forager, reaching lower GUDs, but the difference between species was significant for both seed types only in the under-boulder microhabitat. For sunflower seeds, the difference was also significant in the between-boulders microhabitat. Overall, habitat structure had an overriding effect on foraging behavior for both species. Acomys russatus is more specialized, exploiting a narrower set of microhabitats to greater efficiency, while A. cahirinus is more of a generalist, exploiting more patches with lower efficiency.