Eiders are big strong sea ducks that dive 40 to 50 feet in cold Atlantic water and rip mussels from rocks and swallow them whole.
But as downy hatchlings they are vulnerable to a similar fate from big hungry seagulls.
After last week's ocean storm, a King's Beach walker — alerted by his German shepherd — rescued an eider duckling wrapped in seaweed at the Swampscott shore.
The man brought the duckling home and later talked to Diane Treadwell, Swampscott's animal control officer.
Diane picked up the duckling and drove it to the Marblehead Animal Shelter for care. It was a couple weeks old, and already it had a strong beak.
"He was really cute," she said.
Cute but panicky. Diane figured the eider got separated in the storm from its fellow ducklings and their mother, and the duckling was still calling out for the rest of the gang.
The calls were of two kinds: quaack-like and a rolling loon-like noise.
Diane gave the hungry duckling meal worms to eat.
"The little duckling loved those," she said.
It settled down, sitting on Diane's stomach.
Eiders like other ducks soon bond with humans, she said.
The animal control officer gave the duckling a feather duster and put a mirror in front of it so the bird would think it had company.
It worked. The duckling soon settled in right next to the mirror.
Next stop on the duckling express was the New England Wildlife Center in South Weymouth.
Diane brought the duckling there to get stronger before the center returns it to the wild.
Wayne Petersen of the Massachusetts Audubon Society said eiders are common to the Massachusetts coast during the winter but their numbers are far fewer here in the summer.
As many as a quarter of a million common eiders winter off the Massachusetts coast and nest on islands off the North Shore, Boston Harbor and Cape Cod, said the Audubon spokesman.
Eiders live in multi-family colonies, he said.
The males are delinquent ducks, they bail on the family early.
So several female ducks care for a group of ducklings until they are old enough to fend for themselves, he said.
The ducklings start feeding on their own soon after they come out of the shell. Still, early on, they are vulnerable to predators, he said.
He said the main challenge to caring for an eider in captivity is getting it to eat. They have a specialized diet. In the wild, ducklings will pick food off rocks until they are old enough to dive for clams, crabs and mussels.
But since the Swampscott duckling was eating, the spokesman figures it soon will be strong enough to return to the salt water and will likely do fine.
Diane said the veterinarian at the New England Wildlife Center was excited to see the eider.
Because ducks imprint so readily it is important to get them back with their own kind, she said.
Otherwise they will start to think they belong with humans which would probably make it tougher for them in the wild.