Foraging in the subterranean social Damaraland mole-rat, Cryptomys damarensis:: an investigation into size-dependent geophyte utilization and foraging patterns

The foraging behaviour of captive colonies of the Damaraland mole-rat, Cryptomys damarensis, was investigated in an artificial soil-filled burrow system provided with three tray patches that varied in bulb and corm (i.e., geophyte) density and size. Members of two founder colonies (comprising three and four mole-rats) were exposed to resource patches that varied in food profitability (both size and density of geophytes). There was no preference for excavating any of the patches with different densities or sizes of geophytes. The larger geophytes were preferentially stored and the smaller ones preferentially eaten both on encounter and within the food store. The duration of handling and rate of consumption of geophytes by 15 animals of various body sizes from three colonies were recorded. Handling time was related to the size of the geophytes. Small geophytes were less profitable to consume. It was concluded that the mole-rats generally followed the qualitative predictions of optimal foraging theory but fell short of being energy maximizers.