Bufflehead

Appearance

The Bufflehead ranges from 32–40 cm long and 270–550 g, with the drakes larger than the females. Averaging 35.5 cm and 370 g, it rivals the green-winged teal as the smallest American duck.

Adult males are striking black and white, with iridescent green and purple heads with a large white patch behind the eye. Females are grey-toned with a smaller white patch behind the eye and a light underside.

The name bufflehead is a combination of buffalo and head, referring to the oddly bulbous head shape of the species. This is most noticeable when the male puffs out the feathers on the head, thus greatly increasing the apparent size of the head.

Distribution

They are migratory and most of them winter in protected coastal waters, or open inland waters, on the east and west coasts of North America and the southern United States. The Bufflehead is an extremely rare vagrant to western Europe. Their breeding habitat is wooded lakes and ponds in Alaska and Canada, almost entirely included in the boreal forest or taiga habitat.

Behavior

Buffleheads have evolved their small size in order to fit the nesting cavity of their "metabiotic" host, a woodpecker, the northern flicker. Due to their small size, they are highly active, undertaking dives almost continuously while sustained by their high metabolism. They do not tend to collect in large flocks; groups are usually limited to small numbers. One duck will serve as a sentry, watching for predators as the others in the group dive in search of food. Buffleheads are amongst the last waterfowl to leave their breeding grounds and one of the world's most punctual migrants, arriving on their wintering grounds within a narrow margin of time.

Habitat

They are migratory and most of them winter in protected coastal waters, or open inland waters, on the east and west coasts of North America and the southern United States. The Bufflehead is an extremely rare vagrant to western Europe. Their breeding habitat is wooded lakes and ponds in Alaska and Canada, almost entirely included in the boreal forest or taiga habitat.

Reproduction

Buffleheads are monogamous, and the females return to the same breeding site, year after year. They nest in cavities in trees, primarily aspens or poplars, using mostly old flicker nests, close ) to water. Nest competitors include mountain bluebird, tree swallow, and European starling. There was one recorded instance of a female Barrow's goldeneye killing a bufflehead adult female and her brood. Smaller cavities are preferred because of less competition with the larger goldeneyes. Females may be killed on the nest by mammals, such as weasels or mink, and by goldeneyes over nest competition.

Average clutch size is 9, and eggs average 50.5 by 36.3 mm. Incubation averages 30 days, and nest success is high compared to ground-nesting species like the teal. A day after the last duckling hatches the brood leaps from the nest cavity. The young fledge at 50–55 days of age. Predators of adults include the peregrine falcon, snowy owl, bald eagle, golden eagle, red-tailed hawk, great horned owl, Eurasian eagle owl, and Cooper's hawk.

Food

These diving birds forage underwater. They prefer water depths of 1.2–4.5 m. In freshwater habitats they eat primarily insects, and in saltwater they feed predominantly on crustaceans and mollusks. Aquatic plants and fish eggs can often become locally important food items as well.