The particular morphology of the down of the eider duck makes it the lightest and most effective insulation that is known. It has long been valued: traded by Vikings, hoarded by kings, even accepted as currency in the Middle Ages. The ducks in the Arctic make their nests near human settlements, probably in the hope of protection from their predators – seagulls, foxes and mink – while they sit on their eggs for 28 days. They line their nests with their own belly feathers, which they leave as a gift to their human protectors when once more they return to the sea. As a result the humans fulfil their role as guardians, and watch gun-in-hand through the nights of their nesting.
It seems that the elaborate technique for making such blankets disappeared in the 1940s, and few have survived, among which no other can match the condition of this example. In the Far North moth-proofing was unnecessary, but once they were moved to warmer climes they were extremely vulnerable to moth-attack, which has ruined the blankets that exist in museums collections. The motifs around the border represent the heads of Eider ducks.