Here, we see three male Common Eiders escorting four females at Blue Hill Falls on March 20. The number of these visiting Eiders seems to have dwindled down to less than 50 birds.
They’re leaving for their breeding and nesting grounds, which usually are on sparsely populated or uninhabited sea islands. Maine supports the largest breeding population of Common Eiders in the eastern United States and Canadian Maritimes.
Leighton Archive Image
The birds that we see here are American Common Eiders (Somateria mollissima dresseri), one of three Common Eider varieties in the Atlantic Flyway. The other two are the Northern Common Eider (Somateria mollissima borealis), which nests on the coast of Greenland and other northern latitudes, and the Hudson Bay Common Eider (Somateria mollissima sedentaria), which seems to be mostly confined to the Hudson and James Bay areas in Canada.
Some recent bird counts have indicated that Maine Eider numbers are down in the usual sighting places. One theory for this is that they are still at good numbers, but have shifted congregation and nesting areas due to human and other predator population shifts. (Female Eiders tend to be philopathic; that is, they return to breed on the island on which they were hatched unless there is a significant disruption.)
Another theory is that actual Eider losses have occurred because of reductions in Atlantic Blue Mussels, their favorite food, and/or increases in birds that prey on Eiders (especially Bald Eagles), and/or that prey on their eggs (especially Black-Backed and Herring Gulls). (Brooklin, Maine)