Limpet Patella spp. consumption by oystercatchers Haematopus ostralegus:: a preference for solitary prey items

Patellid limpets are very important grazers on NE Atlantic rocky shores, and can occur in clumps or as solitary individuals. When oystercatchers are foraging for limpets on rocky shores, they are often presented with a choice between solitary and clumped limpets. We attempted to establish whether oystercatchers express a preference for limpet prey items from these different distributions. Oystercatchers spent far more time foraging in areas of less clumped limpets than in areas of clumped limpets, despite lower prey density. We found a strong preference for solitary prey items, and increased chances of successful predation of solitary limpets. Possible explanations for this choice are discussed. This preference for attacking solitary limpets may have important implications for rocky shore dynamics by shaping the spatial patterns of limpets. This may then influence the probability of Fucus germlings escaping limpet grazing.