The carrion connection: Marine mammal carcasses provide an indirect subsidy to insectivorous birds

Abstract

The transfer of energy from nutrient subsidies across ecological boundaries can link the dynamics of adjacent ecosystems. At the interface between land and sea, beach-cast marine mammal carcasses are a large and nutrient-rich food source available to shoreline scavengers. In addition to subsidizing scavengers directly, marine mammal carrion may also indirectly subsidize terrestrial animals by increasing prey abundance. As part of an ongoing study using camera traps to monitor marine mammal carrion along the California coast, I documented a Black Phoebe (Sayornis nigricans) utilizing a California sea lion (Zalophus californianus) carcass to forage for scavenging invertebrates. Given the widespread distribution of pinniped rookeries and terrestrial insectivores, it is likely that insectivores prey upon invertebrate scavengers of pinniped carrion in many locations where they co-occur.