Birds of the Sierra Nevada. Ted Beedy
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squeaking sounds made by their wings in flight. They breed at boreal lakes and marshes throughout the Northern Hemisphere. In winter, they can be found along the coast and in all but the desert regions of the United States, where they frequent large bodies of water. Migratory flocks consisting mostly of juveniles begin to arrive in California by mid-October, but the bulk of their population remains on the breeding grounds until freezing conditions force them southward. While they form large rafts along with other diving ducks in deep water, Common Goldeneyes usually forage near shorelines in water less than 12 feet deep. Preferred foods include mollusks, crustaceans, aquatic insects, seeds, and tubers of aquatic plants. On Sierra lakes and rivers, they sometimes associate with Common Mergansers.
STATUS AND DISTRIBUTION Common Goldeneyes winter at higher elevations of the Sierra than most other diving ducks, except for Common Mergansers and Mallards; there are no breeding records.
West Side. Fairly common winter visitors and spring and fall migrants to most large lakes and reservoirs, as well as slow-moving stretches of major rivers from the low foothills to the Upper Conifer zone.
East Side. Fairly common visitors from November through March from Sierra Valley south; more common in recent decades than in the past.
Barrow’s Goldeneye
Bucephala islandica
ORIGIN OF NAMES “Barrow’s” for Sir John Barrow (1764–1848), an Englishman who promoted Arctic exploration; L. islandica, of Iceland, one of the species’ breeding areas.
NATURAL HISTORY In the Sierra, Barrow’s Goldeneyes are usually found in association with their much more numerous relatives, Common Goldeneyes, on large, deep lakes and rivers. Barrow’s Goldeneyes probably have always been rare nesters in California, as most of their population breeds at secluded lakes of the Cascades, Rockies, and mountainous portions of Alaska and Canada. Similar to Buffleheads and Wood Ducks, Barrow’s Goldeneyes nest in tree cavities such as abandoned woodpecker holes. Birdwatchers in the Sierra should be alert for these strikingly beautiful birds when scanning flocks of Common Goldeneyes.
STATUS AND DISTRIBUTION Historically at least, Barrow’s Goldeneyes were observed breeding in the Sierra, but there are no recent nesting records, despite extensive systematic and incidental surveys in formerly documented nesting areas.
West Side. Uncommon, before the 1940s a few nesting records from the Lassen region south to Fresno County, mostly from high-elevation lakes bordered by forests providing tree cavities for nesting; currently uncommon but regular in winter at Lake Almanor, on the Feather River at the De Sabla Reservoir, and at a few forested lakes and rivers of the central Sierra up to the Lower Conifer zone, with records from the Sonora and Valley Springs wastewater treatment ponds and Moccasin Reservoir (Tuolumne County); casual at higher elevations and south of the Yosemite region.
East Side. Fairly common along the Truckee River west of Reno and at the Truckee gravel ponds (Nevada County), with several birds present every winter; casual in fall and winter at Sierra Valley, and Lake Tahoe, but accidental farther south; careful searching of large goldeneye flocks on larger rivers, lakes, and reservoirs could reveal more records of this species.
Hooded Merganser
Lophodytes cucullatus
ORIGIN OF NAMES “Hooded” refers to the species’ distinctive, crested head; L. merganser, “a diving goose”; lophodytes from Gr. lophion, crest, and dytes, a diver; cucullatus from L. cucullata, a crest.
NATURAL HISTORY Of the three species of mergansers that occur annually in the Sierra, only Hooded Mergansers are restricted to North America, as Common and Red-breasted Mergansers also occur in Europe and Asia. Hooded Mergansers are the smallest and most dramatically colored of the three. At a distance, males might be confused with Buffleheads but their sides are tan, instead of white, and their delicate bills are long and pointed. Unlike the other mergansers that consume primarily fish, Hooded Mergansers also dine extensively on crayfish, amphibians, and aquatic insects—dragonfly nymphs are especially preferred. Their habitat preferences also differ from the other mergansers since they avoid the large lakes and rivers frequented by Commons and salt water preferred by Red-breasted Mergansers. Instead, Hoodeds in the Sierra seek secluded ponds and lakes in winter. Seldom pursued by hunters due to their fishy-tasting flesh, they are still wary ducks that dive or swim for cover when humans approach.
Most of the Hooded Merganser’s western population breeds along the Pacific Coast from southeastern Alaska south to Oregon. Historically they were not considered a breeding species in California, but they have expanded their range southward into the state in recent decades. Hooded Mergansers nest in tree cavities and make use of old woodpecker holes as well as artificial nesting boxes that have been installed widely in California for Wood Ducks—most of the state’s recent nesting attempts have been in boxes.
STATUS AND DISTRIBUTION Grinnell and Miller (1944) described the Hooded Merganser’s status in California as: “Winter visitant, relatively rare . . . never within history appreciably more numerous than now.” Since the mid-1960s, however, more than 100 Hooded Merganser nesting attempts have been documented in at least 20 California counties (Pandolfino et al. 2006). The number of wintering birds in the state has also increased in recent decades.
West Side. Fairly common and widespread winter visitors and spring and fall migrants to wooded lakes and ponds of the foothills regularly up to about 4,000 feet in the central Sierra; most recent nesting records from Plumas, Sierra, and El Dorado Counties, rare or casual south of the Yosemite region.
East Side. Common winter visitors to the Tahoe region, where they are regularly observed Lake Tahoe, Donner Lake, Glenshire Pond (Nevada County), the Truckee River west of Reno; otherwise uncommon migrants and rare in winter; no breeding records.
TRENDS AND CONSERVATION STATUS As noted above, the breeding range of this species has expanded into northern California in recent years. Data from California Christmas Bird Counts show a dramatic increase in the winter population as well. Sierra counts show an even greater positive trend, with numbers up nearly six-fold from the early 1980s.
Common Merganser
Mergus merganser
ORIGIN OF NAMES “Merganser” from L. mergus, a diver.
NATURAL HISTORY These expert underwater hunters require fairly clear water to see their prey. Their long, thin bills have horny tooth–like projections that prevent slippery fish from escaping their grasp. This feature has earned them the epithet “sawbill.” Due to their large size, they are also called “Goosanders” in Europe.
Although they are mostly fish-eaters, Common Mergansers also forage for a diversity of aquatic insects, crayfish, mollusks, amphibians, small mammals, birds, and aquatic plants. These mergansers are often accused of depleting fisheries, but their total impact on fisheries is negligible since they rarely occur in large numbers in any given area. Like other diving ducks, Common Mergansers are clumsy on land and must run across water to take flight. Once flying, their long, straight bodies knife through the air just above the water’s surface, flashing white wing patches. They can be told from all other Sierra ducks by their sleeker profiles and long, narrow bills.
Common Mergansers nest in tree cavities or rock crevices near large streams or lakes; rarely they use artificial nest boxes. Breeding begins in April, and the young can navigate the swiftest streams within a day of hatching. One merganser duckling attempting to cross the Merced River at flood stage was sucked under the waves only to appear about 100 yards downstream, unhurt, and bobbing like a tiny cork. Females tend their young alone until they are independent after about five weeks.
STATUS AND DISTRIBUTION Aside from the ubiquitous Mallards, Common Mergansers are the most abundant and widespread breeding ducks in