IUCN threat status:

Least Concern (LC)

Comprehensive Description

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Barrow’s goldeneye (Bucephala islandica), is a medium-sized duck of the Anatidae family in the Anseriformes order. It inhabits mainly northwest North America from southern Alaska through the U.S. Pacific Northwest, with small populations wintering in eastern Canada and the United States (Eadie, et al 2000). B. islandica usually spends the summer breeding season on cold inland lakes and ponds, normally in forested country, and in winter moves to coastal inlets, bays, and estuaries. The Barrow's goldeneye prefers small bodies of water that are clear of vegetation and have few fish to compete for insects (Kauffman 2018; Seattle Audubon 2018).

Female Barrow’s goldeneyes have brown heads, light gray feathers on their breast, and dark gray or black feathers on their rump. The bill of the female is mostly yellow, and is smaller than the mostly black, yellow-tipped bill of the otherwise very similar common goldeneye (Seattle Audubon 2018). Male Barrow's goldeneyes have iridescent purple heads that look black when not in the sun, and prominent, crescent-shaped white spots near the sides of their black bill. Their backs are mostly black with white spots. Juveniles are mostly gray with brownish heads similar to females, but with less contrast between the head and body colors. Both sexes of the Barrow's goldeneye are between 43-48 cm and weigh between 480-1320 g (Seattle Audubon 2018).

At night, during fall and winter, groups ranging from 5 to 50 individuals sleep on freshwater lakes and sheltered marine coves. These groups break up into pairs or small groups at daybreak to feed. During summer, breeding females are often observed alone or with a mate or brood; nonbreeding females occur in small groups. Males molt in scattered small groups but may form large flocks of several hundred. Migration of inland-nesting birds tends to occur in small flocks (Eadie, et al 2000). They feed mainly on aquatic insects such as dragonfly and caddisfly larvae during the summer, while in winter they eat mollusks, crustaceans, and fish in coastal waters, usually catching their food by diving or swimming. During the summer and fall, they also consume plant material, especially pondweeds (Seattle Audubon 2018; Kaufman 2018).

Barrow's goldeneyes usually form mating pairs in winter. The male’s courtship display involves a turning and pumping of its head, as well as some flapping of its wings. After mating, the female will select a nesting site, often found in large tree cavities, holes, and rock tunnels. The nest the female makes has a slight concaved shape and is lined with sticks, down, and other materials. They usually lay around 7-10 eggs, which range from pale olive to blue-green. The incubation period of the eggs is around 28-34 days, with juveniles leaving the nest about 1-2 days after hatching. The ducklings learn how to fly at about 8 weeks (Seattle Audubon 2018).

B. islandica is very territorial and aggressive and are a main predator in its ecosystem. They are, in turn, prey for several animals, ranging from black bears and raccoons to hawks. Currently they appear to be in little danger regarding population decline (Bird Life International, 2016).

Unreviewed

Creative Commons Attribution 3.0 (CC BY 3.0)

© Anthony Oldershaw, Michael Van Den Kieboom; Editor: Dr. Gordon Miller. Seattle University, EVST 2100: Natural History, Spring 2018.

Supplier: seattleu_natural_history

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