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G.1-3: Where have all the eiders gone?

Presented by Scott Gilliland - Email: sgg64@mac.com

The American Common Eiders breeding range extends from ME to central Labrador and wintering range from insular Newfoundland to RI. Concerns for their status arose around 2005 when large wrecks of eiders tuned up on beaches in MA. About the same time in ME and NS, 10s of thousands of male eiders abandoned moulting sites and banders noted fewer females attending breeding colonies. In 2006, ~72,000 eiders wintered in the Maritimes and by 2019 fewer than 20,000 birds were detected. Analyses of survey and banding datasets suggested steep declines in breeding females at colonies in ME, NB and NS (Lambda~0.93), while colonies in QC (Lambda=1.01) and NL (Lambda=1.05) were stable or increasing. Information from harvest surveys suggested poor productivity maybe partially responsible for the declines and the initial reaction was to blame predation of ducklings by Great Black-backed Gulls. Wellfleet Bay virus, recovery of Bald Eagles, mink, otters and Double-crested Cormorants were also identified as potential factors. However, I speculate that global warming maybe responsible. The Gulf of Maine is warming faster than 99.9% of all other ocean regions on the planet which is having dramatic impacts across the food web, shifting distributions and affecting abundance everything from lobsters to right whales. In particular, blue mussels, the preferred prey for eiders, appear to be negatively impacted by recent warm water events. The loss of eiders wintering in the Maritimes may in part be explained by northern shift in their distribution as the number eiders wintering in the Gulf of St. Lawrence has doubled at the same time. In contrast to terrestrial species which appear to lag behind climate velocities, marine taxa follow climate velocities with surprising accuracy. We suggest the waterfowl community devote more attention to sea ducks and the potential effects of climate change on their distributions and population dynamics.
Session: Climate Change (Thursday, August 29, 8:15 to 10:00)