P-31 El Nino, The Blob, and Egg Cannibalism in Glaucous-Winged Gulls

We studied egg cannibalism in Glaucous-winged Gulls breeding at Protection Island, Washington, between 2006 and 2014 for 7 field seasons. Four of these seasons were preceded by relatively high local sea surface temperatures (SST) associated with El Niño events. During each such season, egg cannibalism was relatively high. By contrast, during the three years of “normal” sea surface temperatures, egg cannibalism was relatively low. Typically, high SSTs are associated with low marine productivity. Thus we hypothesized that high levels of egg cannibalism during years of high sea surface temperatures were due to low food availability. The 2015 and 2016 field seasons were preceded by the highest sea surface temperatures during our 9-year study, yet egg cannibalism was relatively low in 2015 and very low in 2016. Both 2015 and 2016 were accompanied by the existence of “The Blob”, an enormous mass of warm water located in the northeast Pacific Ocean which precipitated significant regional weather and ecosystem perturbations. Although gulls nesting on Protection Island seemed to thrive during these years, other marine birds such as auklets experienced high mortality. Currently we cannot offer a mechanistic explanation for these differences, except to note that feeder fish populations appeared surprisingly robust around Protection Island despite (or because of?) The Blob.