eider duck
(also ‘common eider’ and ‘eider’; pronunciation: the letters ‘ei’ rhyme with the word “eye”)

eider ducks
a kind of bird – sea duck – large bulky body with large wedge-shaped beak (bill), not completely flat like that of a domestic duck; grows to 2-3 feet long and weighs 850 grams to 3 Kg.; feeds on (eats) insects, crabs, clams, shrimps, etc.; lives for about 20 years; found in the Arctic Europe, North America and Siberia

eider quilt/duvet/comforter
baby ~~ duckling
group ~~ colony (during breeding season); flock (while flying)
voice (call) ~~ {different sound for different purposes}
home ~~ nest (for laying eggs and raising ducklings)

eider down -- soft underside feathers
The famous “eider down” is the soft warm breast feathers of a female (duck) plucked to line the inside of its nest before laying eggs.
These feathers have been used for filling pillows and quilts (duvets) by the people. They were in great demand in the past, and consequently, the eider ducks were shot extensively, but now the feathers of eiders bred on farms and the feathers of other farm birds are also used for the same purpose.
{The quilts/duvets/comforters filled with eider ducks’ feathers are also called ‘eiderdown’.}

eider creche
The colour of the feathers of the eider changes between two colours once a year (which is called ‘moulting’).
A unique feature the eiders have is that they keep the ducklings of a colony in groups, like ‘crèche’, and the non-breeding female ducks, “aunts”, take care of them along with the mother ducks!
More from Animals in Language
Python
python: a large python a kind of snake -- reptile -- usually large, muscular and powerful -- grows to 1 metre …
