Birds of the Sierra Nevada. Ted Beedy
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Swan
Cygnus columbianus
ORIGIN OF NAMES “Tundra” for the species’ high Arctic breeding range; “swan” may be derived from an OE. word meaning “sound,” or possibly from L. sonus, a sound; L. cygnus, swan; L. columbianus, of the Columbia River, where the type specimen of the species was collected.
NATURAL HISTORY When sitting on the water with necks erect, Tundra Swans tower above nearby geese and ducks; adults weigh up to 16 pounds and have 7-foot wingspans. Mated pairs stay together for life, and their young become sexually mature after four years. Strong family ties keep related groups together on 5,000-mile round-trip journeys to and from high Arctic breeding grounds. They usually arrive in California by mid-October and depart by mid-March.
Due to their large body mass, swans must run across the water’s surface for a considerable distance before taking flight. Once aloft, their flight is rapid and direct, as V-shaped wedges cut through the sky. Like geese, swans have their legs positioned for good balance for walking and roosting in pastures and harvested grain fields. They are also powerful swimmers and forage in shallow water, wet fields, and irrigated pastures. Swans never dive but instead dip their heads and necks in shallow water and occasionally tip up. After a winter of frequent dipping into muddy or alkaline water, their heads may attain a rusty color. Preferred foods include leaves, stems, seeds, and tubers of aquatic plants as well as the seeds and young shoots of rice and other grain crops.
STATUS AND DISTRIBUTION Tundra Swans are mostly confined to rice-growing areas and wildlife refuges of the Central Valley and California’s northeastern plateau in late fall and winter. Tens of thousands congregate in rice fields north of Marysville, Yuba County, and in the low foothills along Highway 20 between Grass Valley and Marysville, just west of the Sierra.
West Side. Common spring, fall, and winter visitors to Lake Almanor; rare at other foothill reservoirs north of the Yosemite region; casual migrants south to Lake Isabella.
East Side. Uncommon or rare winter visitors to most large lakes and reservoirs; most records in late December or January.
TRENDS AND CONSERVATION STATUS For more than 60 years Tundra Swans have been protected from hunting in California, allowing their populations to recover dramatically from the early 20th century, when they were shot indiscriminately for their plumage. Meat of older birds was considered too tough for human consumption.
Wood Duck
Aix sponsa
ORIGIN OF NAMES Wood refers to the species’ preferred habitat; Gr. aix, waterfowl; L. sponsa, bride, a reference to the male’s elegant plumage.
NATURAL HISTORY The exquisite breeding plumage of male Wood Ducks reflects metallic patterns of green and violet when bathed in sunlight. They are the only North American waterfowl with entirely iridescent wings and backs, and males display more different colors than any other Sierra bird. Females are similar in shape but wear more subdued tones. Their relatively small size (about half the size of Mallards), long tails, and broad wings enable graceful flight through dense woodlands. When disturbed, females make loud, nasal shrieks, and the males give low, squeaky whistles.
As their name suggests, Wood Ducks are partial to forested backwaters, where oaks, willows, cottonwoods, or dogwoods form dense tangles over water. They search for oaks with abundant acorns, an especially favored food. Wood Ducks usually hunt for acorns and other seeds in leaf litter of the forest floor but also land in trees and pluck them from the highest branches. They also forage in water for aquatic plants, insects, and other foods. Wood Ducks usually forage by bobbing at the water surface like puddle ducks but will also make shallow dives for submerged prey.
Courtship behavior begins in midwinter, when females fly to high perches to summon prospective mates; they are unique among Sierra ducks in their ability to perch in trees. Often, several males will compete for a single female until she selects her favorite. Mated pairs show great affection and often preen each other gently on their heads and backs. Females invite copulation by submerging their bodies in shallow water with outstretched heads and necks, as their chosen mate circles nearby.
Cavities in large trees are the Wood Duck’s natural nesting sites. However, most pairs now use artificial nest boxes that have been installed widely in the Sierra foothills and throughout the state. Within a day of hatching, females coax their downy young from the nest. The tiny size and fluffy down of day-old hatchlings allow them to flutter uninjured to the ground from heights more than 50 feet and then walk away to the nearest wetland. Mothers alone guard their broods from predators—including raccoons, river otters, feral cats, opossums, large predatory fish (especially largemouth bass), and non-native bullfrogs—that may consume entire broods. The young are highly vulnerable to predators until they attain flight, which requires up to 70 days. After the breeding season, Wood Ducks do not require densely wooded areas and might be seen floating with other ducks on open lakes and reservoirs.
STATUS AND DISTRIBUTION Year-round residents of the Sierra foothills, Wood Ducks have expanded their distribution upslope in response to the creation of ponds and the placement of artificial nesting boxes.
West Side. Fairly common residents and nesters in bottomlands of all the major rivers from the Feather in the north to the Kern in the south; nesting pairs frequent wooded ponds and stream courses (including beaver ponds) up to about 4,000 feet in the central Sierra, where they remain through the winter even during heavy snow storms.
East Side. Uncommon visitors from spring through fall; nesting pairs at Sierra Valley and, at least historically, at south Lake Tahoe; rarely, nonbreeding visitors observed farther south, with records from Bridgeport Reservoir and Mono Basin in spring and fall; casual to accidental in winter.
TRENDS AND CONSERVATION STATUS Extensive clearing of flooded, bottomland forests eliminated Wood Duck habitat throughout North America. According to William Dawson (1923), their California and continental populations were on the verge of extinction by 1913: “Unceasing exposure to gun-fire has brought its ruin. And for what? Simply that the pot might be kept boiling, and the great American belly might be filled . . . Because its flesh was sapid, its bridal array was stripped from it and flung on the dump, while its quivering ounce of meat went into the pot. The lord of creation has dined—but where is the Wood Duck?”
Although excessive hunting pressure and habitat loss greatly reduced their populations in the early 1900s, they are now fairly common in suitable habitats throughout California. Focused efforts by the California Department of Fish and Game, U.S. Fish and Wildlife Service, California Waterfowl Association, and Ducks Unlimited have greatly increased local populations statewide, including in the Sierra foothills. Data from Sierra Christmas Bird Count Circles and Breeding Bird Survey routes show a stunning increase, with numbers up nearly five-fold since the early 1980s. American Kestrels, European Starlings, Northern Flickers, small owls, honey bees, and wasps may compete with Wood Ducks for these artificial homes.
Gadwall
Anas strepera
ORIGIN OF NAMES Gadwall is a name of unknown origin; L. anas (see family account above); L. strepera, noisy, for the loud calls—similar to a female Mallard’s.
NATURAL HISTORY Compared to other puddle ducks, Gadwalls wear subtle plumage and lack the bright, iridescent hues that characterize this group. In most places these shy ducks are outnumbered by other species, but they have one of the widest distributions of any of the world’s waterfowl and occur on all continents except South America, Australia, and Antarctica.
Gadwalls are primarily freshwater birds but also visit saline and alkaline waters—even in the breeding season. They nest on dry ground near ponds and marshes surrounded by lush aquatic vegetation such as cattails and bulrushes; islands are preferred nest sites. Monogamous