NATURAL HISTORY Unlike most wide-ranging waterfowl, Canvasbacks are entirely restricted to North America. With whitish backs and sides, males stand out among other ducks on the water or in flight. One of the fastest waterfowl, they can attain flight speeds greater than 70 miles per hour. After running across water to become airborne, they fly in V-shaped flocks powered by direct, rapid wingbeats, often at high altitudes. They are also accomplished divers, capable of frequent, sustained dives in water up to 30-feet deep. However, they usually forage in water 10 feet deep, or less, where they search for preferred foods including clams, snails, fish, tadpoles, and wild celery.
While most Canvasbacks breed in the northern prairies and tundra, a portion of their population nests in marshes of the Great Basin, including the northeastern Sierra. Preferred nesting areas are dense freshwater marshes, where females conceal bulky nest platforms of marsh plants under tall emergent plants such as cattails and tules, over or adjacent to water.
STATUS AND DISTRIBUTION Primarily winter visitors to California, Canvasbacks are common in coastal waters and inland on large, open water bodies.
West Side. Rare winter visitors to foothill lakes and reservoirs but significant numbers sometimes found at Lake Almanor; no breeding records.
East Side. Uncommon spring and fall migrants and summer residents; usually scarce in winter but occasionally present in double-digit numbers on Honey Lake or South Lake Tahoe Christmas Bird Counts; rare breeders, with nesting confirmed only in Sierra Valley.
TRENDS AND CONSERVATION STATUS Canvasback populations have declined from their historical abundance across North America in response to changes in land use, loss of wetlands, and hunting pressure. Prized by hunters, the flesh of birds that have consumed wild celery or other aquatic plants (instead of animal foods) is highly sought after. Canvasback populations have remained fairly stable in recent decades (higher numbers in wet years) in response to wetland protection and restoration on their breeding grounds and the enforcement of hunting limits. Numbers from Central Valley Christmas Bird Counts show a significant positive trend since the 1970s.
Redhead
Aythya Americana
ORIGIN OF NAMES “Redhead” refers to the head color of breeding males; L. americana, of America.
NATURAL HISTORY Female Redheads are considered nest parasites because they often lay their eggs in the nests of other ducks—especially those of other Redheads, Canvasbacks, and some puddle ducks. However, some females lay eggs only in their own nests or are partially parasitic. Because of parasitism, their clutch size is difficult to determine but probably averages about 9 eggs; “dump” nests may have more than 40 eggs laid by several different hens. Reproductive success is generally low in this species, resulting from a variety of causes including interference and desertion by parasitic hens, flooding or drying of active nests, and predation by mammals and predatory birds.
Redheads prefer to nest in fresh emergent wetlands where dense stands of cattails and tules are interspersed with areas of open water. For nesting habitat, they select relatively deep wetlands (three feet or deeper) of at least one acre, with about 75 percent open water and vegetation up to about three feet in height. They also nest in somewhat alkaline marshes and potholes of the interior. Nests are built from marsh plants and secured to tall emergent vegetation; they are usually over water but occasionally on islands or dry ground.
In winter and migration, Redheads forage and rest on large, deep bodies of water and may form rafts far from shore. Food is taken mostly by diving in deep water, but they also forage in shallow water. Unlike most diving ducks that prefer animal foods, Redheads consume mostly submergent, aquatic plants such as pond weeds, wigeon grass, and duckweed, but they also take aquatic insects, grasshoppers, larvae of midges and caddisflies, small clams, and snails.
STATUS AND DISTRIBUTION Redheads are year-round residents in California, but the small breeding population is supplemented by northern migrants in fall and winter. They winter primarily along the coast and at large, inland water bodies.
West Side. Rare or uncommon spring and fall migrants and winter visitors; breeding suspected at Lake Almanor but has been confirmed only at the Kern River Preserve (i.e., Prince’s Pond) near Lake Isabella.
East Side. Fairly common spring and fall migrants and summer residents, especially in wet years when freshwater marshes provide large areas of suitable habitat; occasionally present in fair numbers in winter on lakes and reservoirs; breeding documented at Honey Lake Wildlife Area, Sierra Valley, Mono Basin, Crowley Lake, and other Mono County sites.
TRENDS AND CONSERVATION STATUS Once considered the most abundant diving ducks in California, the state’s breeding and wintering Redhead population has been greatly reduced since the early 1900s, primarily due to the loss of permanent wetlands throughout the Central Valley and historical hunting pressure. Called “fool ducks” by some hunters, they are easy to decoy and hunt compared to most other waterfowl. Based on declines in the Redhead’s overall population size and range, and continuing threats (e.g., ongoing wetland losses, nesting failures, and historical and possibly recent hunting pressure), the state’s breeding population was added to the California’s list of Bird Species of Special Concern in 2008.
Ring-necked Duck
Aythya collaris
ORIGIN OF NAMES “Ring-necked” for the chestnut-colored neck bands of breeding males; L. collaris, collared.
NATURAL HISTORY Despite their name, male Ring-necked Ducks have chestnut collars so faint they are difficult to see even at close range. From a distance their dark heads and backs, vertical white stripes on the leading edge of the flanks, and white ring around the bill tip make much better field marks—they might be more properly named “Ring-billed Ducks.”
Ring-necks tend to flock with members of their own kind on farm ponds and reservoirs; they almost never occur on salt water. Like most divers, they must run across the water surface for a considerable distance before taking flight. Wintering flocks frequent large, open bodies of water. In contrast, nesting pairs select smaller, secluded lakes and ponds—often surrounded by forest. Females build nests of grasses and aquatic plants, usually near or over water. Primarily vegetarians, their main foods include pondweeds, smartweeds, and occasionally insect larvae.
STATUS AND DISTRIBUTION Ring-necked Ducks are visitors and migrants to California, including both sides of the Sierra.
West Side. Fairly common fall and winter visitors to low-elevation lakes, ponds, and reservoirs the length of the West Side; rare nesters with breeding only documented at Buck’s Lake but probably breeds at other deep lakes of the northern Sierra; pairs in suitable Sierra breeding habitats have been seen in midsummer as far south as Madera County south of Yosemite National Park, suggesting a recent southward-range extension.
East Side. Uncommon fall visitors to larger lakes and reservoirs; hens with broods at secluded lakes in the Tahoe Basin, Meiss Lake (Alpine County), and at Crowley Lake.
Lesser Scaup
Aythya affinis
ORIGIN OF NAMES “Scaup” was modified from OE. scalp, shellfish, a food of this species; L. affinis, allied with or related to, refers to close relationship to the larger Greater Scaup (A. marila), a rare species in the Sierra (see Appendices 1 and 2).
NATURAL HISTORY As their name suggests, Lesser Scaup are slightly smaller than their close relatives, Greater Scaup. The two species are often lumped together by hunters who call them “blue-bills,” or “bluies,” instead of scaup.
Lesser Scaup are restricted to the Western Hemisphere, where they breed in subarctic wetlands of Alaska and Canada and winter as far south