On the biology of Sundevall's jird (Meriones crassus Sundevall, 1842) (Rodentia : Gerbillidae) in the Negev Highlands, Israel

Abstract

Data on the biology of Meriones crassus in the Central Negev are presented based on 3.5 years of field observations and data on mark-recapture of 392 individuals. Constant sexual differences in body mass were shown, whereas seasonal variation of body mass was observed in years with low food availability only. Reproduction was observed from January to September with peaks in February-May and August. Duration of pregnancy was 18-22 days and the litter size was 3-7 pups. Details of postnatal development are provided. The dynamics of age structure was related to the patterns of reproduction. Longevity in the field was up to two years and in captivity it was more than three years. The species is relatively low habitat-specific : it only avoids rocks and occurs in all other habitats. The highest density (up to four individuals per 1 ha) was found in sand dunes. Habitat selection is seasonally variable and is determined by different environmental factors in different seasons. Pattern of individual space use is characterized by periodical strong territorial conservatism. Observations on radio-implanted M. crassus showed that an individual remained in close vicinity of its burrow during the entire night for a relatively long period. Then, it moved to another burrow where it stayed for three-seven nights. Jirds had relatively short periods of aboveground activity (5-10 % of dark time) ; activity was restricted to the area under shrub canopy just near the burrow. All individuals were highly infested by fleas. Four flea species were recorded. The most common flea in most habitats was Xenopsylla conformis, whereas in wadis covered with loess it was replaced by Xenopsylla ramesis.