Bufflehead
Order: Anseriformes
Family: Anatidae
Genus/Species: Bucephala albeola
 |
A pair of Buffleheads Photo by Kate Volz, NZP |
Description: The chunky little Bufflehead is the smallest diving duck native to North America. Males seldom exceed 1 lb. in weight and the smaller females weigh on average less than 12 oz. Buffleheads are sexually dimorphic in plumage as well as overall size. Breeding males have black backs and white underparts. Their wings are black with a large white patch covering the secondary flight feathers and a large portion of the coverts. Their heads are predominantly black with iridescent green and purple highlights. A wide white patch extends from just behind the ears all the way to the back of the head. Their bills are blue-black in color. Females are mostly dark brown on the back, head, and wings with paler gray underparts. They have a small half-dome shaped patch of white feathers below the ear and a small white wing patch. The bill of the female is dark brown to black. All Buffleheads have dark brown eyes and pink legs and feet. Male Buffleheads in non-breeding plumage closely resemble the females but can be distinguished by their larger size, slightly larger cheek patch, and larger wing patch. Juveniles are grayish-brown with small indistinct cheek patches.
Buffleheads are agile swimmers and divers but awkward on land because their legs are set well back on their bodies. In flight they are one of the fastest of all the waterfowl, and can be recognized by their small size and rapid wing-beat.
They are relatively quiet ducks. Males during courtship emit a variety of sounds described as squeaks, chatters, growls, and guttural rolls. Females also employ a loud guttural call during courtship and nest site searches. Hens with broods use soft contact calls to keep the ducklings together and a louder alarm call when danger threatens.
The common name Bufflehead is a corruption of the original name Buffalo Head, a reference to the disproportionately large domed head of the drake. The Bufflehead has a host of other colorful nicknames including: Bumblebee Dipper, Robin Dipper, Hell-diver, Spirit Duck, and Butterball.
Distribution and Habitat: The breeding range of the Bufflehead is restricted to the woodlands of North America. The vast majority of the population breeds in a wide band of boreal forests and aspen parkland stretching from Alaska to Manitoba. Smaller, isolated populations breed in Ontario, Washington, Oregon, California, Idaho, Montana, and Wyoming. There are sporadic reports of birds breeding in Quebec, Vermont, Massachusetts, Minnesota, South Dakota, and Colorado. They winter in highest densities along the Pacific (southern British Columbia to California) and Atlantic coasts (New Jersey to North Carolina), with smaller inland wintering populations in California, Mississippi, and New Mexico.
Breeding habitat must include suitable nest trees. Buffleheads prefer to nest in the abandoned holes of Northern Flickers. Nesting habitat usually includes poplar or aspen trees near freshwater permanent ponds or lakes. Wintering coastal birds prefer the shallow water shelter of coves, estuaries, beaches and harbors.
Diet: Diets vary with the type of habitat and the season. In freshwater habitats they concentrate on aquatic insects including: damselfly and dragonfly larvae, midge larvae, caddisfly larvae, mayfly larvae, water boatmen, and amphipods. Birds wintering in saltwater habitats feed on clams, shrimps, snails, amphipods, isopods, and occasionally fish. In the fall, winter and spring they may consume more plant material such as the seeds of pondweeds and bulrushes.
Adult Buffleheads feed almost exclusively under water. They prefer to feed in open shallow water or along the edges of emergent vegetation. Foraging birds divide their time almost equally between shallow dives and rest periods on the water surface. Dives average 12.5 seconds in length. Prey is swallowed while under water. During the shortest days of winter birds may be forced to continue foraging for hours after dark to secure enough prey to survive.
Reproduction: Buffleheads form monogamous pairs. They may even keep the same mate for several successive years as pairs return to the same breeding territory and nest tree season after season. Because of the long-term nature of the pair bond, Bufflehead pairs engage in courtship displays in nearly every season of the year. Displays occur in the air and on the water and include fly-overs, head-shakes, wing-lifting, and head bobbing. The drakes can erect their head feathers to double the size of the white cheek patch and make their heads appear almost circular in profile. Territorial males may defend small lakes or ponds to exclude other Buffleheads and even waterfowl of other species. After an aggressive display toward an intruding male, the territory holder will swim vigorously about with the female following with her neck out-stretched.
Though their small size enables female Buffleheads to squeeze through cavity entrances as narrow as 2.25 inches in diameter, competition for nest sites is fierce. Woodpecker holes are in high demand by all cavity-nesting animals, leading Buffleheads to compete with starlings, bluebirds, squirrels, and Barrow’s Goldeneyes, as well as members of their own species. Nests are most commonly found in aspen and poplar trees and can be as far as 425 meters from the nearest water, though within 25 meters is more common. Nest height is dictated by cavity availability and can range from 0.6 to 27 meters above the ground. They will readily accept nest boxes where available, but prefer small nest boxes with small openings. The female lays 6-11 eggs, which she incubates alone for 28 to 33 days. The entire clutch will hatch within a 24-hour period. The brood remains in the nest for 24-36 hours after hatching. When the young are ready to leave the nest the hen will spend some time at the cavity entrance surveying her surroundings for danger before she drops to the ground and calls to her ducklings to follow her. She will then lead her family on a perilous overland journey before reaching the safety of water
Conservation: Overshooting in the late 19th and early 20th centuries reduced Bufflehead populations. They have made a slow but steady recovery through the middle of the 20th century thanks to protective legislation and treaties between the United States and Canada. More recently the clearing of aspen parklands for agriculture and commercial logging activities have steadily reduced the amount of suitable breeding habitat. Wintering birds may be acquiring detrimental levels of heavy metals and other toxic contaminants as they shelter in heavily industrialized areas, particularly along the east coast of the United States. The total population of Buffleheads in 1992 was estimated to be around 1.4 million birds.
References:
Del Hoyo, J., Elliot, A. and J. Sargatal. eds. 1992. Handbook of the Birds of the World. Vol. 1. Ostrich to Ducks. Lynx Edicions, Barcelona.
Gauthier, G. 1993. Bufflehead (Bucephala albeola) In The Birds of North America. No. 67 (A. Poole and F. Gill, Eds.) Philadelphia, PA. The Academy of Natural Sciences; Washington, D.C.: The American Ornithologist's Union.
Madge, S. and H. Burn. 1988. Waterfowl. Houghton Mifflin Co., Boston.
Todd, F. S. 1996. Natural History of the Waterfowl. Ibis Publishing Co., San Diego, CA.
