Eiders perform courtship rituals Incubating females don’t eat for 26 days

When I first moved here I lived near the coast and quickly became familiar with our sea ducks.

Common eiders became my favorite. They were abundant and easily observed, but they also seemed to exude a certain mystery. They seemed to embody the wildness of cold northern seas and the rocky Maine coast.

In the spring, I’d visit Bass Harbor Head Light, or hike Ship’s Harbor Nature Trail, on the western side of Mount Desert Island. The trail opened out onto pink granite ledges overlooking the mouth of Blue Hill Bay and down in sheltered areas of the water I’d see females with their fluff-ball young.

Later in the season, I’d see females lead their young – no longer fluff-balls, now more closely resembling the adults – onto rocks exposed by receding tides, for extended (and comical), preening sessions.

During a fall or winter hike atop a mountain in Acadia National Park, I’d scan the ocean far below through my binoculars and see great rafts of them spread out over the wind-whipped surface.

I’ve come full circle once again. Over the last several weeks, I’ve noticed the eiders breaking up their large winter flocks. Just recently I observed a small group of three females and four males and was treated to some interesting behavior.

I first noticed the sound they were making, a very deep-pitched, almost cattle-like lowing. At first their movements seemed random, but soon they appeared to be swimming in formation. The males, especially, began to exhibit very ritualized grooming, bathing and wing-flapping movements. As if following a choreographer’s cue, they all dipped their beaks into the water simultaneously and repeatedly.

At times, one of the birds – usually a male, sometimes a female – would rear up in the water and slowly, deliberately flap its wings. This pose, which is so often captured in photographs, is a common breeding and territorial display.

For all the posturing and displaying, the birds appeared calm. There were no aggressive interactions, except when one of the males approached a female. She then wasted no time in turning on him and sending him unceremoniously scuttling out of her way.

Eider ducks are thought to be largely monogamous, and appear to maintain pair bonds throughout the year and across years in some cases, according to the “Birds of North America,” species account.

They nest in colonies on islands at sea. Females select the nest site and build the nest, which is a hollow in the ground lined with the downy feathers from their own bodies.

Usually, a female will lay a clutch of three to five eggs and incubate them for approximately 26 days. She is the only one to incubate, and is not fed by her mate at all during this time. In fact, about midway through the incubation period, her mate departs to a molting area.

She may at first take short breaks to drink fresh water, but she does not leave the nest long enough to be able to feed herself. As incubation progresses she leaves the nest less and less.

Luckily, once the chicks hatch they are amazingly precocial and within 24 hours are able to leave the nest and feed themselves as they follow the hen. And so begins a new cycle for these tough northern seabirds.

bdnsports@bangordailynews.net