4 September 2012

The other day at Acadia National Park I watched a female common eider (Somateria mollissima) climb up on a boulder and eat the barnacles.  At one point she opened her wings and I saw that they were surprisingly short.

Since eiders are the largest duck in the northern hemisphere they need substantial wings to fly but this bird’s wings weren’t long enough to carry her.  Why?  She was molting.

Like many ducks and geese, common eiders completely molt their tail and wing feathers in late summer after the breeding season.  This means they can’t fly for 3-4 weeks.

This isn’t a terrible hardship for eiders because swimming is their most important skill.  It’s how they get their food (marine crustaceans) and how they avoid predators.

Like eiders Canada geese go through a flightless period, too, but I never noticed it.  They hide it well.

It’s taken me a long time to realize that I’ve never seen a common eider fly because I only visit their home when they’re flightless.

(photo by Stuart Burns via Wikimedia Commons.  Click on the photo to see the original)