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December 2020

Vol. 48, No. 6

Front Cover: December 2020

Canvasback by Barry Van Dusen

About the Cover Artist

An artist who has created many of our covers, Barry Van Dusen lives in Princeton, Massachusetts, and is well known in the birding world. Barry has illustrated several nature books and pocket guides, and his articles and paintings have been featured in Birding, Bird Watcher’s Digest, and Yankee Magazine as well as Bird Observer. Barry’s interest in nature subjects began in 1982 with an association with the Massachusetts Audubon Society. He has been influenced by the work of European wildlife artists and has adopted their methodology of direct field sketching. Barry teaches workshops at various locations in Massachusetts. For more information, visit Barry’s website.

Canvasback

The Canvasback (Aythya valisineria), with its distinctive wedge-shaped head and bill and striking color pattern is, to many observers North America’s most elegant waterfowl. The male in breeding plumage has a chestnut red head tinged with black, a black breast and tail, and a white body. The long, sloping bill is black. Females in breeding plumage are similar in pattern to males, but the body is mottled gray and the head and breast are brown. Males in nonbreeding plumage have mottled gray bodies. Juveniles resemble females but are darker. The Redhead male, which has a similar color pattern to its Canvasback counterpart, differs in having a rounded head, gray back, and a light blue, black-tipped bill. Female Redheads are a uniform brown color and have a gray, black-tipped bill. Canvasbacks are monotypic with no subspecies described.

The Canvasback breeding range extends in a swath across central Alaska, south through the prairies and parklands of western and central Canada, and into the United States south into the Dakotas and Minnesota to the east, and in scattered localities from Wyoming and Washington to northern California to the west. Canvasbacks migrate along all of the major flyways in the United States. They winter in scattered concentrations along the West Coast from southern British Columbia through Baja California and along the East Coast from Massachusetts to central Florida. They also winter inland from the southern Great Lakes across much of the lower half of the United States. Their wintering range extends through the northern two-thirds of Mexico in patches of suitable habitat. In Massachusetts today, Canvasbacks are considered a very uncommon and local winter resident, despite their former occasional abundance as recently as the 1970s. Their local movements reflect changing winter conditions such as the icing up of ponds.

Canvasbacks are usually monogamous, but males sometimes breed with a second female, leaving the original mate when she is incubating eggs. Courtship begins during spring migration. The female has the dominant role in pair formation because she chooses her mate from a half-dozen or more males that may court her simultaneously. Courtship occurs on the water where she may swim along a preferred male. She may give a head-lowered threat display to one male and then give a neck-stretched display with head, neck, and bill stretched upward to the favored male. Both males and females give the stretch display. Males have several displays in which they may lower the head with crown feathers depressed, hold the head in the normal upright posture, or hold the head forward with various types of coughs given. In another display, males throw the head and neck backward until the crown touches the back, then snap the head forward. Canvasbacks are not vocal but give a variety of coughing sounds—rrrr, kuk, or ker—during courtship displays.

Canvasbacks breed in wetlands that include marshes, sloughs, lakes, ponds, or potholes. They tend to be nest-site faithful, returning to the same breeding areas year after year. The female alone constructs the nest over water of local emergent vegetation. The base is a bulky platform that may rest on the muddy bottom in shallow water or be attached to emergent plants in deeper water. The nest is a depression of finer plant fibers lined with down. It usually has a ramp or two leading to the water and a canopy of overhanging vegetation. The female has a single brood patch, and she alone incubates the 7–12 grayish olive eggs for the 3–4 weeks until hatching. The male remains with the female for a week and then deserts her. During that week, the male defends the nest site against intrusions by other Canvasbacks or Redheads. The hatchlings are precocious—they are covered with down, and their eyes are open. They leave the nest the day after hatching and can feed themselves. The female leads the chicks to larger ponds that have underwater vegetation and usually stays with her brood for 3–8 weeks before heading off to molt. The young are capable of flight about two months after hatching.

During the flightless period associated with molt, Canvasbacks stay on ponds and lakes where they can feed on submerged vegetation. Males, after abandoning the females, move to staging areas, including lakes and prairie and tundra wetlands. They complete their molt and migrate before the females and young birds, who generally stay in the breeding area but move locally to open water to molt. On the staging and wintering grounds Canvasbacks are gregarious, sometimes aggregating in flocks of more than a thousand, and flying in small flocks in V-shaped formations.

Canvasbacks take a broad spectrum of plant and animal food. On the wintering grounds they mainly take aquatic plants such as wild celery; on the breeding grounds they also take gastropods, small clams, and a variety of insect larvae. They are highly versatile foragers, taking plants and insects from the water surface and under water, taking insects from the air, and probing the substrate. They can dive to nearly 30 feet. Canvasbacks may defend a particularly rich resource.

Canvasbacks are subject to nest predation by mink, foxes, coyotes, raccoons, skunks, and weasels, and the usual avian predators including crows, gulls, and owls. They are also subject to brood parasitism by other Canvasbacks and by Redheads. Redheads may even push Canvasback females off the nest to lay eggs. When the Canvasback strongly resists, her eggs may be cracked or shoved out of the nest. Hunting is a significant cause of death, but current conservation efforts and hunting season regulation aim to keep the breeding population level above a half-million birds. Conservation initiatives include keeping motorboats away from staging areas and restricting fishing in sensitive areas. Let us hope that these efforts will keep this elegant waterfowl’s population stable so Canvasbacks are visible for birders into the future.

William E. Davis, Jr.


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