Eider, EYE duhr, duck is the name of four species of ducks known for their soft, warm down feathers. Eider down is a light, highly efficient insulating material and is used to make pillows, bedding, and coats. It grows under the duck's outer feathers and is collected from nests in the early summer. Eider ducks live in northern coastal areas of North America, Europe, and Asia. Adult males have spectacular colors and patterns on the head. Females are dark brown with brown and black streaks.