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1. The aridity food‐distribution hypothesis (AFDH) maintains that ecological constraints and foraging risks in arid environments curtail dispersal and promote the evolution of cooperatively foraging social groups within African mole‐rat populations. To assess the influence of habitat constraints upon mole‐rat social behaviour and hence the validity of the AFDH, we investigated the differential patterns of dispersal and philopatry in two populations of the common mole‐rat, Cryptomys hottentotus hottentotus Lesson, one from a more ‘optimal’ habitat (mesic) and another from a ‘suboptimal’ habitat (arid).

2. Rates of immigration and emigration were markedly lower in the arid relative to the mesic site, reflecting divergence in the ecological constraints upon dispersal.

3. The rates of dispersal at both sites increased as a function of group size. However, for any given group size, colony attrition was significantly greater at …