Birds of the Sierra Nevada. Ted Beedy. Читать онлайн. Newlib. NEWLIB.NET

Автор: Ted Beedy
Издательство: Ingram
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Жанр произведения: Биология
Год издания: 0
isbn: 9780520954472
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filled with nearby stems and grasses to form a shallow bowl. Typically females lay one egg per day, but during severe snow storms up to eight days may lapse before another egg is laid. The young are brooded by both parents until they can fly and forage alone; broods remain together until the following spring.

      White-tailed Ptarmigans are native to Alaska, western Canada, and isolated pockets of the Rocky Mountains—but not the Sierra. The California Department of Fish and Game introduced White-tailed Ptarmigans to the Sierra simply because the Alpine zone had no game birds for hunters. This is especially ironic because nearly all currently inhabited sites are in National Parks where hunting is prohibited. Although there is no documentation of detrimental effects of this introduction, ecologists have long known that non-native animals can have unpredictable, and sometimes disastrous, effects on native plants and animals, which have coevolved over thousands or millions of years.

      STATUS AND DISTRIBUTION All White-tailed Ptarmigans in the Sierra originated from a transplant of about 70 birds from Colorado released at two sites near Eagle Peak and Twin Lakes, Mono County, in 1971 and 1972 (Frederick and Gutiérrez 1992). Since then, the species has spread to about 50 miles north, 20 miles west, and 70 miles south of the release sites.

      West Side. Uncommon residents; recorded in Humphrey’s Basin and Dusy Basin in Kings Canyon National Park and as far north as Carson Pass, El Dorado County; breeding populations occur near the crest in the Yosemite Sierra near Gaylor Lakes, Granite Lakes, Mono Pass, and Dana Plateau, and as far west as Mount Hoffman, near the geographic center of Yosemite National Park.

      East Side. Uncommon residents, mostly confined to the Alpine zone along the crest, but spring sightings at about 8,000 feet in Lundy Canyon, Mono County, suggest downslope movements in winter to avoid heavy snow; also observed near Pine Creek, Green Lake, Brown Lake, and Piute Pass, Inyo County.

      Sooty Grouse

      Dendragapus fuliginosus

      ORIGIN OF NAMES “Sooty” for dark plumage; formerly called Blue Grouse, now considered a distinct species from Dusky Grouse (D. obscurus); see “Status and Distribution” below; Gr. dendragapus, tree loving; fuliginosus from L. fuligo, sooty.

      NATURAL HISTORY Sooty Grouse are more often heard than seen. Males of this species congregate in loose “hooting groups” from late April to early July to proclaim their territories with a series of resonant, booming calls. These calls are lower in pitch than those of any other Sierra bird, so low that some people cannot hear them. Two yellow air sacs on the neck, usually hidden, are inflated to produce these unmistakable notes. Finding a hooting male is seldom easy, because he makes ventriloquial calls from a hidden perch high overhead in the foliage of a dense conifer. Visitors to higher forests may hear, and feel, these haunting calls echoing through the woods for hours at a time.

      Most Sooty Grouse in the Sierra breed in the Upper Conifer zone, where they can be found in open or partly brushy slopes with nearby stands of densely foliaged conifers for roosting and hooting. Large trees are preferred—especially Douglas-firs, white firs, red firs, and Jeffrey pines. Adult males arrive on breeding territories by early March, followed shortly thereafter by females and yearling males. Throughout the nesting season, the promiscuous males remain on their territories and attempt to court and mate with receptive females attracted by their calls. Once mated, a female prepares a nest by lining a shallow depression on the ground under a shrub, tree, or log with leaves and grasses.

      The young eat mostly insects, a source of protein, for at least ten days after hatching then switch to conifer needles and seeds. By late summer, mothers with young disperse both upslope and downslope from their nesting grounds, feeding in meadows and brushy hillsides, where they are often surprisingly tame. An encounter with a family group inspired John Muir (1901) to write: “One touch of nature makes the whole world kin; and it is truly wonderful how love-telling the small voices of these birds are, and how far they reach through the woods into one another’s hearts and into ours.” During spring, summer, and fall, Sooty Grouse forage mostly on the ground, eating seeds, berries, green shoots, and insects. Adults also fly up into conifers to browse on needles and buds. These hardy birds survive high-elevation winters by taking shelter in dense firs, pines, and hemlocks and eating needles, buds, and pollen cones.

      STATUS AND DISTRIBUTION In 2006 the American Ornithologists’ Union split Blue Grouse into Sooty Grouse occurring in the Sierra, Cascades, and coastal ranges of California, Oregon, and Washington, and Dusky Grouse that live in the Rocky Mountains and Great Basin. Sooty Grouse undertake both upslope and downslope movements in spring and fall. In the Pacific Northwest they are known to migrate upslope for the winter, and birds at Sequoia National Park have also been observed to undertake such “backward” migrations.

      West Side. Uncommon residents of the Upper Conifer zone, males and some females wander up to tree line after breeding where they remain until late fall; rare in Lower Conifer zone in fall and winter.

      

      East Side. Uncommon residents of ponderosa and Jeffrey pine forests up to the Subalpine zone; populations at Sagehen Creek (Nevada County) remained at their breeding elevations through the winter but similar studies are lacking from other areas.

      TRENDS AND CONSERVATION STATUS The “Mount Pinos” Sooty Grouse (D. f. howardi) is a distinct subspecies restricted to the southern Sierra, south of Kings Canyon National Park, including the Piute Mountains, as well as ranges to the south of the Sierra including the Tehachapi Mountains and Mount Pinos. Recent surveys suggest that they may be extirpated from most of the southern portion of their historical range. Extensive surveys in 2002 in the Greenhorn Mountains (northernmost Kern County) found only eight birds in what is likely now the southern edge of their range. Continuing threats include habitat degradation due to harvest of large trees, fire suppression and uncontrolled wildfires, and livestock grazing. This subspecies was added to the list of California Bird Species of Special Concern in 2008.

      Wild Turkey

      Meleagris gallopavo

      ORIGIN OF NAMES Turkey, considered foreign and exotic when the species was first introduced to Europe in the 16th century; a possible reference to Asia Minor, a source of exotic goods at that time; Gr. melagris, spotted, for the species’ patterned plumage; L. gallopavo, from gallo, a cock, and Sp. pavo, a turkey.

      NATURAL HISTORY With their dazzling, iridescent bronze plumage, Wild Turkeys are elegant versions of common barnyard turkeys, a breed domesticated during pre-Columbian times in Mexico. Wild Turkeys are not native to California, but birds captured in Mexico were first introduced to mainland California for hunting in 1908. While most early introductions failed, subsequent releases over many decades were more successful and the species is now widespread in suitable habitats throughout the state. Most of the successful introductions to California were from wild populations in Mexico, Virginia, and Texas. Attempted introductions by the California Department of Fish and Game, U.S. Forest Service, and the National Wild Turkey Federation at high elevations of Sierra, Nevada, and Placer Counties as recently as 1997 should be discouraged because this species may compete with native species of quail and grouse with unknown consequences. They have also been observed to scour entire hillsides for snakes, lizards, and invertebrates having obvious but unmeasured impacts on those species.

      Turkeys roost in trees but forage on the ground in forest openings, eating insects, green plants, seeds, acorns, and fruit. Throughout the year Wild Turkeys associate in groups, which consist during the breeding season of a “gobbler” male and his harem of four to six hens. In the Sierra the breeding season extends from late March until August, with a peak in May and June. Prior to pair formation, three to six males may strut together to attract a large group of females. The polygynous males perform courtship, a series of gobbling and strutting displays to attract females to be added to their harems. Conspicuous during courtship, fertilized hens sneak away from the immediate breeding area and are secretive when preparing to nest. They create shallow scrapes for nests and line them with leaves and grasses. Young are tended by hens alone