Common eiders can live from 28 years and 4 months to 47 years and 3 months, with a maximum lifespan of 24 years and 7 months, and a theoretical lifespan ranging from 26 years and 7 months to 38 years; the species reaches sexual maturity between 7 months and 3 years. The eyes of a chick open at birth, and during the "Embryo" stage, the embryo develops inside an egg and does not feed itself. Following hatching, the "Chick" stage lasts from 1 day to 2 months and 1 week, with the young being covered in thick down and soon leaving the nest. The "Rapid Growth Juvenile" stage begins after the young starts flying and lasts from 2 months and 1 week to 2 years, during which time it learns to find food independently. The “Adult” stage, when the bird is capable of reproduction, lasts from 2 to 20 years.