Birds of the Sierra Nevada. Ted Beedy
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breeding season—female poults tend to remain with their mothers longer than males. With the inclusion of juveniles, winter flocks are larger than breeding flocks, and up to 100 birds might be seen foraging together on an oak-studded hillside.
STATUS AND DISTRIBUTION In the Sierra, Wild Turkeys spend most of the year in the Foothill zone, but they can be fairly common in the Lower Conifer zone in summer; postbreeding birds have been seen up to 10,000 feet on the Kern Plateau of the southern Sierra. In winter, they move as much as 50 miles downslope in search of areas with plentiful food and little snow, especially in foothill oak woodlands and chaparral.
West Side. Common to abundant in most areas of the foothills.
East Side. Uncommon; established populations near Honey Lake, in Alpine County, and near Topaz Lake.
TRENDS AND CONSERVATION STATUS Data from Breeding Bird Surveys and Sierra Christmas Bird Counts confirm the stunning increase in numbers and expansion of range for this species. In less than 30 years, Wild Turkeys have gone from unrecorded to abundant throughout the western foothills. Noted on only a couple of Sierra Breeding Bird Survey routes prior to the late 1980s, Wild Turkeys are now found consistently on more than 40 percent of the routes. Impacts to other species from this invasion are not yet evident.
LOONS
Family Gaviidae
Called “divers” in Europe, loons are sleek-bodied and superbly adapted to aquatic habitats but are almost helpless on land. Laterally flattened legs, set far back on their bodies, do not enable them to walk or stand, so loons can only move on land by sliding on their bellies. Unlike grebes, which have lobed toes, loons have webbed feet. They are also strong fliers but cannot take off from land; instead, they take flight after a long running start over open water, often into a stiff wind. Once aloft, they fly with quick, shallow strokes on slender, pointed wings. On a dive, their large, paddle-like feet propel them to great depths. Genetic studies indicate that loons are unlike any other living order of birds, not related (as once thought) to grebes. Fossil evidence shows that they have an ancient lineage dating back more than 65 million years. Males and females share identical breeding and winter plumages, but males are usually larger. There are only five species of loons worldwide, and all of them breed in North America. Two species, the Pacific and Common Loons, regularly occur in the Sierra. The family name is derived from L. gavia, a seabird.
Pacific Loon
Gavia pacifica
ORIGIN OF NAMES “Loon” may be a reference to the species’ wild calls, “crazy as a loon”; L. gavia (see family account above); L. pacificus, of the Pacific.
NATURAL HISTORY Pacific Loons consume mostly small fish captured by diving in deep, open water. They often swim with their heads and necks partially submerged, “snorkeling” for fish that they pursue at depths up to 70 feet. Behavior and habitat preference in the Sierra are very similar to Common Loons (see account below).
STATUS AND DISTRIBUTION Pacific Loons breed in Alaska and northern Canada and migrate south in small flocks to spend the winter along the Pacific Coast. In California most of the population winters in protected bays and coastal estuaries not far from shore, but migrants stray to large, inland water bodies including in the Sierra.
West Side. Uncommon fall, winter, and spring visitors; observed in most years at foothill reservoirs; rare above the Foothill zone but almost annual fall and winter records from Lake Almanor and other large mountain lakes and reservoirs up to the Subalpine zone.
East Side. Uncommon visitors to Lake Tahoe and large reservoirs such as Stampede Reservoir (Sierra County), Boca Reservoir, and Bridgeport Reservoir and Lake Crowley, and June Lake from November through May.
Common Loon
Gavia immer
ORIGIN OF NAMES Sw. immer, ember, blackened ashes, a reference to the dark upperparts of breeding adults.
NATURAL HISTORY Common Loons have not been recorded as a California breeding species since the mid-1920s, when a few pairs and young birds were observed at Eagle Lake and other lakes near Lassen Volcanic National Park. Among the world’s most accomplished diving birds, Common Loons make foot-propelled dives that may exceed depths of 200 feet. Small fish are their preferred prey, but they also consume crustaceans as well as aquatic insects and plants, including algae. Although capable of extremely deep dives, Common Loons usually forage in relatively shallow, nearshore waters. While swimming along the water’s surface, they may partially submerge their bills and cock their heads to “snorkel” for fish underwater. Upon spotting a prey item, they roll forward slowly in a smooth arc, with wings closed, and are capable of long underwater pursuits. These large-bodied loons ride low in the water when actively foraging, but float higher when resting or preening. Usually observed in winter plumage in the Sierra, Common Loons molt into breeding plumage by mid-April prior to migrating north to breed. Although rarely heard, these birds do give eerie yodeling calls from time to time, even in midwinter.
STATUS AND DISTRIBUTION Visitors from northern breeding grounds, most Common Loons in California remain in coastal waters. Each year, however, many regularly appear on large lakes and reservoirs of the Sierra.
West Side. Fairly common and regular fall and winter visitors to such large reservoirs as Lake Almanor, Millerton Lake, Lake Success, and Lake Isabella; rare nonbreeding individuals remain through summer; casual in late summer and fall at large Subalpine lakes, such as Tenaya Lake in Yosemite National Park.
East Side. Fairly common in fall, winter, and spring at large water bodies, such as Lake Tahoe, Topaz Lake, Stampede Reservoir (Sierra County), Boca/Prosser Reservoirs, and Bridgeport Reservoir, Crowley Lake, and June Lake but usually depart when substantial areas of open water freeze.
TRENDS AND CONSERVATION STATUS While late-19th century accounts documented Common Loons nesting just north of the Sierra at Eagle Lake, and at a few other large lakes above 5,000 feet east of Mount Lassen, they were probably extirpated as a breeding species in California by the early 1900s. The following account by C. H. Townsend (1887) is one of the only descriptions of Common Loons nesting from the Lassen region: “I waded out to a narrow sand bar . . . upon which a (Common) Loon had been sitting, and found her nest or rather egg . . . which was lying on the sand.” The cause of the Common Loon’s disappearance as California breeders is unknown, but it may have been related to human disturbance of nest sites. Studies in other parts of North America have shown that the mere presence of boats, even a single canoe passing too close, can cause Common Loons to abandon their nests and young. Formerly, Common Loons were included on the list of California Bird Species of Special Concern (Remsen 1978), but they were removed from this list since extirpation as a breeding species in California happened more than 100 years ago.
GREBES
Family Podicipedidae
Wedded to water at all seasons, grebes feed, sleep, court, and nest on water. At a distance, they look somewhat like ducks but tend to sit higher on the water and have shorter bodies, more slender necks, and sharp, pointed bills. Rather than webbed feet, they have individually lobed toes that fan out when pushed through water, as do coots and phalaropes. Grebes can dive 20 feet or more and stay submerged for up to a minute. Similar to loons, grebes swim underwater with great strength and agility, propelled by legs set so far to the rear that they cannot walk upright on land. They are rarely seen in flight, and even when pursued by predators, they usually flee by diving. Most grebes migrate at night, and a few species (such as Eared Grebes) travel thousands of miles between their breeding and wintering grounds. Female grebes usually lay three to six whitish eggs and cover them with moist nesting material when leaving their nests, causing eggs to become stained reddish-brown before they hatch. Both adults participate in incubating the eggs for about 20 to 25 days. Information on the behavior of nestlings is lacking for many species, but most young grebes attain