Birds of the Sierra Nevada. Ted Beedy
Читать онлайн книгу.AND DISTRIBUTION First introduced to California in 1932, Chukars are now established on both sides of the Sierra, with the largest populations east of the crest.
West Side. Uncommon; breeding populations in the foothills of Fresno County up to about 12,000 feet in Tulare and Kern Counties (including the Kern Plateau), and possibly in the foothills below Yosemite National Park, where first introduced in the 1960s at the Red Hills south of Chinese Camp, and Horseshoe Bend Mountain near Lake McClure.
East Side. Fairly common and widespread below the pine forests along Walker Creek and in the Bridgeport Valley and south to the Mono Basin, and just east of the Sierra in the Bodie Hills; locally fairly common in eastern Lassen, Sierra, and Plumas Counties; fairly common to common in the vicinity of several desert oases south to at least Butterbredt and Jawbone Canyons; has been recorded in Owens Valley.
Ring-necked Pheasant
Phasianus colchicus
ORIGIN OF NAMES “Ring-necked” for the male’s bright white neck ring; pheasant from Fr. faisan, a pheasant; Gr. phaisianos, a pheasant; cholchius for the Colchis region near the Black Sea in central Asia, where the species is native.
NATURAL HISTORY Ring-necked Pheasants are native to Asia and have been widely introduced to suitable habitats throughout North America, where they are now the most widely hunted upland game bird. Pheasants prefer grain or hay fields, often those with weedy margins or wetland vegetation nearby, where they forage for cultivated grain seeds, fruits, nuts, and insects. Highly adapted to life in cultivated fields and other disturbed areas, Ring-necks probably do not compete with native species of grouse or quail for food or habitat.
The bold plumage of adult males makes them easy to spot in open fields and sparse grasslands, but they can disappear entirely in even the sparsest cover when pursued by hunters or their dogs. Pheasants “freeze” until almost stepped on before erupting into flight with an enormous racket of beating wings and cackling calls. The subtle brown plumage of females enables them to stay mostly hidden, even in plowed fields, but they are almost as noisy and conspicuous as males when flushed. In early April, females begin to select their nest sites in tall vegetation near their winter foraging areas. Hens excavate shallow depressions where they toss nearby twigs, leaves, or grasses together. Chicks can fly and forage independently at about two weeks of age.
STATUS AND DISTRIBUTION Ring-necked Pheasants were introduced into California as early as 1855. They are now abundant residents in agricultural areas of the Central Valley but uncommon or absent from most of the foothill areas.
West Side. Uncommon in the Kern River Valley, the only well-established population; birds are found consistently on a couple of low foothill Christmas Bird Counts in Placer and Tulare Counties.
East Side. Uncommon residents of agricultural fields near Honey Lake with numbers on recent Honey Lake Christmas Bird Counts lower than those seen in the 1980s and 1990s; released into the Owens Valley in the early 1900s with numerous other introductions by the California Department of Fish and Game until 1977; confirmed breeding near Lone Pine (Inyo County) in 2003, but most introductions have been unsuccessful.
Greater Sage-Grouse
Centrocercus urophasianus
ORIGIN OF NAMES “Sage-Grouse” for their dependence on sagebrush; Gr. centrocercus, sharptailed; urophasianus from Gr. oura, tail, and L. phasianus, a pheasant.
NATURAL HISTORY Perhaps the most inspiring Sierra birding experience is waking up in the predawn chill to view the elaborate and spectacular strutting displays of the Greater Sage-Grouse, the largest native North American grouse. As soon as the snow starts to clear in early March, males gather at traditional “lek” sites to attract females on open hillsides, grassy swales, recently burned areas, or dry lakebeds, surrounded by sagebrush—the species’ preferred nesting habitat. Leks are collective display grounds composed of small, individual territories defended by different males. Strutting displays involve a complex sequence of stereotyped postures characterized by vertical fanning of the long, sharp tail feathers, lowering of wings, and inflating of air sacs to display two olive-green skin pouches. Individual displays last about three seconds but are repeated many times during the early dawn hours. Breeding displays also include an array of strutting calls, fighting calls, low grunts, and loud popping sounds.
Displays and vocalizations serve as an alternative to physical aggression, and displaying males rarely engage in direct physical combat with other males. Leks consist of 20 or more competing males and the oldest ones, “master cocks,” are the most successful. Typically one or a few males achieve more than 90 percent of all copulations. Clusters of hens gather together and serve as a sexual stimulus for other females that engage in precopulatory squatting before accepting the advances of the dominant males. After hours of preparation, the copulation only lasts a few seconds. Birders and photographers should exercise extreme caution when viewing Sage-Grouse strutting displays and should only view them from well-concealed sites at a distance of 100 yards—or more.
Once fertilized, the hens leave the strutting grounds and seek out nesting sites under the overhanging cover of sagebrush or tall grasses to provide thermal cover and protection from predators. Hens care for their precocial young for at least several weeks. Young are capable of foraging on their own within a few hours of hatching, and insects such as ants and beetles are an important component of their diet. Preferred foods of adult Sage-Grouse include the fresh leaves and buds of sagebrush as well as grasses, flowers, fruits, and a few insects; in winter, Sage-Grouse subsist entirely on sagebrush leaves, a diet unique among North American birds.
STATUS AND DISTRIBUTION Greater Sage-Grouse are residents of sagebrush flats in the Great Basin, and their range extends into the eastern Sierra.
West Side. No records.
East Side. Uncommon to rare and highly localized; some lek sites in the region persist at isolated locations near Honey Lake, west of Bridgeport Valley, Mono Basin, and Long Valley (Mono County); also just east of the Sierra in the Bodie Hills and White Mountains (Mono and Inyo Counties).
TRENDS AND CONSERVATION STATUS Due to their dependence on sagebrush, Sage-Grouse are adversely affected by land management activities that degrade their habitat, such as overgrazing by cattle and wild horses, unnatural colonization of sagebrush habitats by Utah junipers and pinyon pines, uncontrolled and destructive wildfires, and fragmentation by roads and housing subdivisions. Historical hunting pressure was also a factor in the species’ decline, but strict controls since the 1980s suggest that hunting is not a current threat to their population. Such recreational activities as off-highway vehicles and uncontrolled viewing and photography of active leks can result in reproductive failures. “Green energy” projects, such as solar and wind, that destroy thousands of acres of pristine desert or sagebrush habitat, are also a significant but unmeasured threat. For these reasons, the species was included on the 2008 list of California Bird Species of Special Concern.
White-tailed Ptarmigan
Lagopus leucurus
ORIGIN OF NAMES “White-tailed” for the species’ distinctive field mark; “ptarmigan” is probably derived from a Gaelic word “tarmachan,” the “p” is silent and based on historical misspelling; Gr. lagopus, hare-footed, a reference to the species’ feathered tarsus and feet; Gr. leucurus, white-tailed.
NATURAL HISTORY Brown and white in summer, these Arctic grouse molt into pure white plumage in winter to match their snowy surroundings. White-tailed Ptarmigan are silent most of the time, but both males and females utter loud “flight screams” when flushed, and territorial males emit “gobbling” calls to attract females. Males are generally monogamous, but some are polygynous and court two or more females. Pair formation begins from late April to mid-May. After copulation, females use their feet and bills to excavate shallow scrapes on the ground