Coexisting populations of Acomys cahirinus and A. russatus: a preliminary report

Two species of the genus Acomys, cahirinus and russatus, co-occur in En Gedi. A. cahirinus is nocturnal, whereas A. russatus is diurnal. This pattern of temporal partitioning has been ascribed to competitive exclusion of A. russatus by A. cahirinus. Study of the ecological basis for this phenomenon and its mechanisms, however, is still required. Here we report preliminary results of long—term research that we undertook in order to establish precise activity patterns, body temperature rhythms, spatial distribution, food habits, and population dynamics of the two species. Population densities of both species are quite low, and much lower than those found in agricultural areas. A. russatus was found mainly in a creek bed strewn with boulders, and also on the hillside among boulders. A. cahirinus appeared to be more evenly distributed, and was found also among smaller rocks; determination of precise spatial distribution patterns, however, requires more thorough study. While A. cahirinus was active al...