Pinniped predation of birds: A cause for conservation concern?

ABSTRACT Recovering predators can create challenges for conservation objectives when they prey on vulnerable species. Although largely uncommon, pinniped predation of birds presents one such challenge. Here, we describe the novel characteristics of this predator–prey interaction, its impact on bird populations, and possible mitigation responses. We do so both broadly, synthesizing the wider literature, and specifically, in reference to ongoing South American sea lion (Otaria flavescens) predation of Black-necked Swans (Cygnus melancoryphus) we are currently observing in southern Chile. Our review of the literature suggests that in most cases bird predation by pinnipeds is only exhibited by a small proportion of the population, spreads socially between individuals, can be temporally severe, and may rapidly threaten the viability of bird populations. We discuss feasibility and efficacy of potential mitigation measures highlighting that, as foraging specializations can be socially transmitted, any such actions need to be time conscious as bird-killing behaviors may be increasingly difficult to remove. The contrasting population trends of pinnipeds and seabirds suggests that pinniped predation of vulnerable waterbirds is going to be an increasingly common conservation challenge in the future.