MINIMIZING INTERSPECIFIC COMPETITION BY DIFFERENT FORAGING STRATEGIES IN 2 NORTH AFRICAN DESERT RODENTS

In most deserts, rodent species are represented numerously, most of them being granivorous. Several studies deal with the question, what the mechanisms of coexistence in such rodent communities are. In this paper the hypothesis is tested, whether the two locomotion types - quadrupedal running and bipedal saltation - may be responsible for the syntopic occurence of the two granivorous desert rodent species Jaculus jaculus (Linnaeus, 1758) and Gerbillus gerbillus Oliver, 1801. The behaviour analysis in a special observation laboratory has shown that the bipedal J. jaculus is less attached to the burrow site, covering a wide area with a wide-meshed net of locomotion pattern, and using only a small part of discovered food resources. The quadrupedal G. gerbillus shows a close contact to the burrow, an intensive utilization of the area round the burrow, and a food utilization of nearly 100%. According to these different strategies in searching for food and food utilization the conclusion can be drawn that (1) by using a wide area J. jaculus always finds new food patches, and (2) that G. gerbillus profits by the fact, that J. jaculus never uses a food patch in total.