Common Eider

• The female plucks down from her own breast to line the nest — eiderdown.
• It is the largest duck in the northern hemisphere.
• Males leave the female as incubation begins, so she is alone for almost four weeks.

Skeleton type

Vertebrate - pneumatised bony skeleton (bird)

Habitat and environment

Rocky Arctic and subarctic coasts of the northern hemisphere, on both the Atlantic and the Pacific

Birth weight

Exact weight at hatching not found as a precise figure

Size at birth

Precocial, covered in dark brown down, able to swim and feed itself almost at once

Sexual maturity

Female: ~2 years | Male: ~3 years

Gestation / incubation

25-28 days

Litter / clutch size

2 to 8 eggs per clutch (most commonly 4-5)

Sources consulted: Planet of Birds; A-Z Animals; AnAge (genomics.senescence.info); Animal Diversity Web; Simply Birding; U.S. Fish & Wildlife Service; Massachusetts government wildlife fact sheet