Changes in foraging effort in two gerbil species correlate with habitat type and intra- and interspecific activity

Gerbillus allenbyi and G. pyramidum were studied in an area containing semistabilized dunes and stabilized sand fields in the Negev Desert, Israel. In both species that per capita foraging and non-foraging activity was negatively and significantly correlated with its own population density. When G. pyramidum was common, G. allenbyi limited most of its activity to the stabilized sand while most G. pyramidum activity occurred in the semistabilized dunes. With no or one G. pyramidum present, most G. allenbyi activity was shifted to the semistabilized dune. Per capita activity of both species declined significantly as a function of the increasing activity of the other, but the decline in per capita activity of G. allenbyi in the presence of G. pyramidum was significantly greater than the decline in per capita activity of G. pyramidum in the presence of G. allenbyi. In stabilized sand, per capita activity of each of the species was also significantly correlated with the density of the other species. The asymmetric interspecific competition probably fits the shared preference habitat selection model. -from Authors