Will increased storm-surge frequency impact food availability for Semipalmated Sandpipers Calidris pusilla at the beginning of fall migration?

Hatch-year Semipalmated Sandpipers Calidris pusilla use river deltas along the Beaufort Sea coast of Alaska as their first stops during fall migration. However, these sites are subject to extreme changes in water levels that affect available foraging habitat. We examined relationships between timing of fall migration and storm surges, with respect to forage availability, using different water level scenarios to predict impacts on food availability for fueling migration at three river deltas. We compared available calories at observed water levels to modeled values derived from changes due to lunar (classic) tides (35% decline) and storm surges (58% decline). Peak use by shorebirds varied temporally among sites, while the peak in forage availability occurred late in the season, mismatched with the largest peak in migration at the most used river delta. Shifts in breeding phenology due to climate warming may allow shorebirds to migrate earlier and miss some storm surges, but this may create a mismatch between peak migration and greater food availability. Additionally, changes in climate will likely increase frequency and severity of storm surges that negatively impact availability of foraging habitat for migrant shorebirds.