Behavioural correlates of spatial distribution in Wagner's gerbil Gerbillus dasyurus (Rodentia, Gerbillinae)

Spatial organization of Gerbillus dasyurus in the Central Negev (Israel) is characterized by isolated aggregations of several individuals within a hom ogeneous habitat. We studied the behavioural interactions between individua ls from the same and from different aggregations in male-male and female-fe male dyadic encounters on neutral arena. We tested the hypothesis that betw een-individual relationships, in G. dasyurus populations are in accordance with the << dear enemy >> phenomenon (individuals show more aggressive beha viour upon detecting strangers than when sensing neighbours). The number of cohesive interactions between gerbils was much higher than that of agonist ic behaviours. Male opponents in neighbour dyads demonstrated both agonisti c and cohesive interactions significantly less frequently than opponents in non-neighbour dyads. No significant difference either in manifestation or in frequency of behavioural items were found between neighbour and non-neig hbour dyads of females. Male encounters were more asymmetric than female en counters in terms of defensive behaviour, but not in terms of offensive beh aviour. No difference in behavioural asymmetry between neighbour and non-ne ighbour encounters of both sexes was found. It is noteworthy that the defen sive asymmetry was significantly higher than offensive asymmetry in male en counters.