Coexistence of temporally partitioned rocky desert rodents: Foraging microhabitat use under diurnal and nocturnal physiological pressures and predator regimes

We studied foraging microhabitat use of nocturnal Acomys cahirinus and diurnal Acomys russatus at En Gedi. We defined four microhabitats: under boulder (UB), between boulder (BB), open near (ON; 2.5 m from boulder field), and open far (OF; 5 m from boulder field). We placed a seed tray in each microhabitat (a total of 40) and measured giving up densities (GUDs) at sunrise and sunset for three to five consecutive days and nights during winter and summer. Both species foraged preferentially in microhabitats that provide overhead cover and hiding spaces: GUDs were lowest in UB followed by BB, ON, and OF. Acomys cahirinus uses a broader range of microhabitats, foraging only the richer food patches. Acomys russatus restricts its foraging to the boulder habitat and prefers BB where it forages to low GUDs relative to A. cahirinus. Trade-offs in foraging efficiencies leading to different strategies of microhabitat use may enable the two species to coexist. Both species shifted their foraging activity toward more open habitats in summer compared with winter. This shift is compatible with an avoidance response to snakes that are active in summer, and is opposite of the expected for A. russatus in the hot summer. During summer there is an increasing ecological overlap in foraging microhabitat choice and efficiency. Both species are highly insectivorous in summer, and may reduce food overlap by taking of prey that are temporally partitioned.