Food storage and carrion feeding in the fiddler crab Uca lactea

Abstract

Food hoarding is an adaptive strategy that enhances survival and reproductive success in food-scarce environments. It has been assumed that food hoarders, especially vertebrates, have the ability to cache food based on their current requirements and expected reproductive success. The present study provides empirical evidence that food storage in aquatic invertebrates is dependent on the availability of food and semilunar intertidal rhythms. The white-clawed fiddler crab Uca lactea, which inhabits food-scarce sandy mudflats, usually feeds on organic materials in sediment and occa- sionally on animal carrion, including conspecifics. This food is brought by the fiddler crabs into their burrows, presumably to be consumed during flood tides or heavy rains when the crabs cannot emerge to feed at the surface. When food was supplemented in the sediment every other day, females tended to store food-enriched sediment into their burrows. This behavior peaked around spring tides, when females were reproductively most active (i.e. mate-searching and mating). These results suggest that females may increase their reproductive effort by storing food.