Influence of spatial heterogeneity on coastal otter (Lutra lutra) prey consumption

Abstract

We studied otter diet in a heterogeneous coastal environment in S Spain including sandy and rocky coastal habitats as well as four small Mediterranean-regime streams. The main sources of environmental variation (rocky coast vs. sandy coast, coastal habitat vs. inland habitats) were clearly reflected in the otter diet composition. In rocky coastal transects otters intensely predated on wrasses, blennies and rocklings, while in sandy coastal ones eels, flatfish and crayfish were characteristic prey types. Grey mullet was the most important prey type in terms of biomass in both coastal environments. Fish consumption clearly decreased from coastal habitat to inland ones. Otter prey were heavier in coastal than in inland habitats, while consumed fish were heavier in the sandy coast than in the rocky one. Within the wide habitat variation in the study area, otter foraging efficiency was considered maximum in estuarine environments.