Barrow's goldeneye is a type of duck common to Canada, Greenland, Iceland, and the northern United States. Normally wintering in mountainous regions, this duck spends its breeding season around lakes where populations of insect-eating fish are small or nonexistent. The scientific name for Barrow's goldeneye is Bucephala islandica.
A medium-sized duck, the Barrow's goldeneye averages between 17 and 19 inches (43–48 cm) in length. Both the non-breeding male and the female look very similar, with dark brown heads, gray backs and wings, white chests and bellies, and small triangular bills. Breeding males, however, have dark purple, nearly black, heads with a white crescent marking near their bills. Their backs and wings are black, with square white markings on each side and white secondary feathers on their wings.
Although these ducks eat fish eggs, invertebrates, and occasionally vegetation and small fish, during breeding season their primary food source is aquatic insects. For this reason, they tend to avoid bodies of water with many insect-eating fish so they do not have high competition for their chosen food source. To catch its prey, the Barrow's goldeneye dives under the water from its surface position. Sometimes whole flocks dive in unison.
A long-lived species, the maximum age ever record for a Barrow's goldeneye was 18 years. Females mature later than many other duck species as well — not usually beginning to breed until they reach three years. Pair bonds are formed after a courtship process and are dissolved after the female lays her eggs. The bonds are, however, usually taken up again in the next breeding season.
Nests are normally built in tree cavities and are lined with feathers. Females normally return to their birth sites to breed and, once a suitable nesting spot is found, will often use the same cavity year after year. Normally, the female will lay six to 12 eggs and incubate them herself. From time to time, females will lay their eggs in another's nest, and those eggs will be taken care of by the nest's owner. Once the eggs hatch, the ducklings are mobile after two days. Young fledge in eight or nine weeks.
Although the mother takes care of her ducklings until they fledge, the young need little care. Highly independent, the ducklings are capable of finding food on their own. All ducklings are provided some parental care, however, and females will take charge of more than one brood when young have found themselves without a mother.