Preferential predation by American black oystercatchers on transitional ecophenotypes of the limpet Lottia pelta (Rathke)

Three ecophenotypic forms (rock, Egregia, Mytilus) of the limpet Lottia pelta (Rathke) are described. When ecophenotypes move among substrata their shell color and morphology change, and an ontogenetic record of past microhabitats is preserved in the shell. Collections of prey items from American black oystercatcher Haematopus bachmani Audubon nest sites along the central California coast demonstrate that specimens of L. pelta that have changed substrate occur at a significantly higher frequency than would be expected based on their presence in the adjacent rocky intertidal, and we propose that the discontinuities in shell pattern make these limpets more obvious to visual predators such as oystercatchers. Limpet shells indicate that the direction of movement is primarily from unstable ( Mytilus and Egregia habitats) to stable (rock) substrata.