Biology of Wagner's gerbil Gerbillus dasyurus (Wagner, 1842) (Rodentia

We present data on the biology of Gerbillus dasyurus in the Central Negev based on 5 years of field observations and mark-recapture data of 893 individuals. The region is dominated by large erosion cirque. We sampled 45 plots in a variety of habitats in and around the cirque. Constant sexual differences in body size and mass were shown (with males generally larger and heavier) as well as variation in body mass among habitats, between seasons and among years. Reproduction was observed almost year round with a pause in December. Duration of pregnancy was 18-22 days and the litter size was 3-7 pups. There was constant male bias in the sex structure of the population in both adult and young animals. The dynamics of age structure were related to patterns of reproduction. Longevity of both males and females in the field was up to 2.5 years and in captivity was more than four years. The main factors affecting the distribution of the species in the study area were soil-structure variables. G. dasyurus avoided patches with sandy soils, and demonstrated intermediate selectivity for patches with high rock and clay content. Simultaneously, G. dasyurus mostly utilized sites with relatively high abundance of annual vegetation and shrub crown volume (suggestive of preference for highly productive and moderately covered patches, and avoided extremely dense vegetation). The highest density (up to 50 individuals per I ha) was found in loess hills. Habitat selection was not seasonally variable. Two types of burrows were recorded. Simple burrows with 1-3 openings and without a nest were more abundant than complex burrows with 4-5 openings and a nest chamber with a nest.