The bird order Procellariiformes (albatrosses, shearwaters, petrels) have evolved a specialized mode of chick provisioning, where adults concentrate the oils from prey for direct delivery of energy-rich lipids (“stomach oil”) to offspring. This contrasts with the approach used by most seabirds in which chicks are supplied with whole prey. The stomach oil strategy is assumed to have evolved to supply chicks with an energy-rich food supply that buffers them from variation in parental foraging success. However, this strategy may have health implications for chicks, as any contaminants in the prey will be concentrated in the stomach oil.
We are investigating this stomach oil strategy in Leach’s storm petrels (LHSPs; Oceanodroma leucorhoa), an abundant Procellariiform seabird that nests on remote islands in the Northwest Atlantic. Petrels spend most of their lives at sea and only come to land to breed. Stomach oil was collected from one adult in the monogamous breeding pair and from their chick in a population of LHSPs nesting on Kent Island, a small island southeast of Grand Manan in the Bay of Fundy, in 2010 and 2011.
The stomach oil is then analyzed for energy content and lipid composition. From stomach oil samples collected in 2010, we have found that the energy content is more energy dense than whole prey items that other seabirds would feed their chicks, suggesting LHSPs can concentrate energy in stomach oil. Contaminant analysis of stomach oil revealed that the stomach oil is more concentrated than in prey items, suggesting that contaminants are concentrated in the stomach oil. This project will provide insights into the costs and benefits associated with a highly evolved provisioning strategy that is used by Procellariiformes across the globe.