Gray whales may increase feeding opportunities for avian benthivores

Feeding by gray whales Eschrichtius robustus along the eastern Pacific coast between the Bering Sea and Baja, Mexico, appears to be increasing. Gray whale feeding can disturb large fractions of intertidal and shallow subtidal sediments, altering the distributions of benthic invertebrates for many months. Increased gray whale feeding may be modifying foraging profitability for other bottom-feeding vertebrates along the coast, but such effects have not been documented. This paper is the first report of a feeding association between a cetacean and bottom-feeding birds, namely a migrating gray whale and diving sea ducks. Local counts and condition of surf scoters Melanitta perspicillata in Puget Sound, Washington, suggest that gray whale feeding can provide important foraging opportunities for scoters during spring, when other foods may have declined and requirements to prepare for migration and reproduction are high. Complementary data are needed to evaluate the importance to scoters of this seasonal interaction with gray whales. However, given the large and protracted impacts of gray whales on benthic communities, our observations suggest that whale feeding may have increasing influence on the foraging patterns and trophic relations of a range of bottom-feeding vertebrates.