Common eiders gather in coastal waters

The waters off Portland shimmer with late spring light, and if you listen carefully over the sound of small waves against the rocky shore, you might hear the soft conversational murmur of sea ducks riding the swells. Common Eiders (Somateria mollissima) have returned to these Maine waters, their heavy bodies sitting low in the water like dark corks. The males flash white backs and black bellies, while the females wear intricate brown barring that breaks up their silhouette against the waves.

These are not passing migrants but homecomers. Common Eiders spend most of their lives at sea, diving for blue mussels, sea urchins, and crabs in depths up to sixty feet. Their bills are perfectly adapted for this work, flattened and broad with sensitive edges that can feel along rocky crevices underwater. What brings them to shore now is the ancient pull of breeding season. Pairs form through elaborate courtship displays where males throw back their heads and call with hollow, musical notes that carry across the water. The female chooses her mate, and together they scout the coastline for nesting sites.

Eiders nest on islands and rocky points where land predators cannot easily reach them. The female builds her nest in a shallow scrape, lining it first with seaweed and grass, then with the famous eider down she plucks from her own breast. This down, with its extraordinary insulating properties, will keep her eggs at exactly the right temperature even when she leaves to feed. She incubates alone for nearly a month while her mate returns to sea, often joining bachelor flocks that molt together in late summer. The ducklings hatch covered in dark down and follow their mother to water within hours. They cannot dive yet, so they feed at the surface on small invertebrates and algae until their flight feathers develop.

The eiders gathering in these waters now represent a remarkable recovery story. Their populations crashed in the early 1900s due to hunting pressure and egg collection, but protection under the Migratory Bird Treaty Act allowed them to rebound. Still, they face new challenges. Climate change shifts the distribution of their shellfish prey, and rising sea levels threaten low-lying nesting islands. The invasive Common Periwinkle (Littorina littorea) now dominates many intertidal zones where eiders once foraged, creating a less diverse food web. Yet the birds adapt, adjusting their diving patterns and sometimes traveling farther to find the blue mussel beds and urchin populations they depend on.

Close your eyes and listen for their voices mixing with the rhythm of water against stone. The sound carries the weight of deep ocean and the lightness of birds coming home to nest, a conversation between sea and shore that has shaped this coast for thousands of springs before this one.