Spatial and temporal aspects of reproduction in North Carolina fiddler crabs (Uca pugilator Bosc)

Male courtship cycles, female cycles of mating, incubation and larval release, and foraging patterns of Ucap ugilator Bosc found on sloping and elevated flat salt marsh beaches in North Carolina were studied to identify correlates between the spatial and temporal distribution of resources and behavioral differences. We also compared temperate and subtropical (Florida) populations. All showed semimonthly cycles of reproduction. However, North Carolina crabs courted, mated, and spawned within the intertidal zone, rather than above it as did Florida crabs, probably because salt marsh substrata provide stable (non-collapsing) incubation chambers for brooding females. Crabs on sloping beaches foraged in herds at food-rich lower zones during both diurnal and nocturnal low tides. Those on elevated flats, where the food supply is uniformly distributed, rarely left their burrows to feed. When herding occurred, it was primarily during new moon nocturnal low tides. Finally, crabs on elevated flats exhibited temporally restricted spawning periods compared to those on sloping beaches where water depths, even during the neap tides, were sufficient for larval release.