Кларк қазғырының сипаттамасы мен ерекшеліктері

Species of bird

Clark's grebe (Aechmophorus clarkii) is a North American waterbird species in the grebe family. Until the 1980s, it was thought to be a pale morph of the western grebe, which it resembles in size, range, and behavior. Intermediates between the two species are known. This species nests on large inland lakes in western North America and migrates to the Pacific coast over the winter. It maintains local populations year round in California, Nevada, and Arizona (the Lower Colorado River Valley), as well as in central Mexico. It feeds by diving for insects, polychaete worms, crustaceans, and salamanders. It performs the same elaborate courtship display as the western grebe.

The "Clark" of its common name—and its specific epithet clarkii—honors John Henry Clark, a 19th century American surveyor who was also a naturalist and collector. The genus name Aechmophorus comes from the Ancient Greek words αἰχμά (transliterated "aichme"), meaning 'point of a spear', and φόρος ("phoros"), meaning 'bearing'; together translating as 'spear point bearer' and referring to the bird's long, dagger like beak. In Mexico, it is called achichilique pico naranja (the western grebe is called the achichilique pico amarillo). A common name advocated in Spain for this bird is the calque achichilique de Clark.

Clark's grebe closely resembles the western grebe and occurs in the same colonies together with it. Storer and Nuechterlein in 1992, following earlier morphological studies by Storer and others, define the species as being distinguished from the western grebe by an overall paler plumage on its back, as well as a larger portion of its face covered in white, as it extends above the eyes, rather than just below them. A distinguishing feature is its bill, which is bright yellow in the US, whereas the Western Grebe's bill is greenish yellow in the US, which had been noted by others. Storer and Nuechterlein in 1992 claim that the bill is slightly upturned in this species whereas the western grebe has a straight bill, this was not noted in earlier studies. There are few changes between the sexes, the most notable feature that distinguishes males from females is the presence of a slight crest on the heads of males. In juveniles, the plumage is again similar to the Western Grebe, however it is also paler compared to the greyer Western species. Although darker and lighter colored morphs of grebes occur in the resident non migratory populations occur in Mexico, it is unclear if these can be distinguished by the other morphological characteristics described above, as most studies have only looked at US populations. Lighter colored morphs in Mexico are said to have orange coloured bills, and the darker morphs have yellow bills. In the winter in California numerous examples of dark colored western grebes displayed the mostly white face of Clark's grebe, although this was intermediate and thought to be possibly due to seasonal changes.

This taxon is extremely similar to the western grebe: it has the same behaviour, including the elaborate courtship displays, occurs sympatrically in the same range and has the same migrations, and is morphologically almost alike, with this bird most noticeably being somewhat paler in colouration. The two taxa can even successfully cross breed, with intermediates as a result. As such, it was commonly thought to be a paler colored morph (a version with paler colours and more white), as occurs in many bird species. In 1858, the lighter coloured morph had first been described as a separate Mexican and Californian species, Podiceps clarkii by George N. Lawrence. Lawrence cited three specimens as representative of his new species, but did not cite a specific holotype. Of the three specimens Lawrence used, two were larger, migratory birds from California, whereas a single specimen was a smaller bird from Laguna Santa Maria in Chihuahua. Deignan designated this last specimen as the holotype in 1961.

Being waterbirds, they require bodies of water that offer the necessary food and shelter that they need to thrive—usually lakes or suitable wetlands—that are also in proximity to suitable tree cover that they can use for nesting. The range of this bird in Mexico is distributed in two streaks southward; one from the California border along the Pacific coast throughout Baja California and across the gulf along the coast to southern Sonora, the other a higher altitude, inland distribution running down from the Big Bend region behind the Texas border down the mountains of central Mexico, with the highest concentration in population in the south from Jalisco to Puebla and northern Oaxaca, where the distribution abruptly ceases. These two distributional areas representing where grebes have ever been seen only meet each other in the very north of Mexico in a strip along the USA border, to the south they do not come together and are separated by a very large distance. It is completely absent from the Atlantic coast. These courtships take place during spring migration and shortly after arriving on the breeding grounds. It is important to note that while there are very few cases of breeding between clark's and western grebes, there have been cases where phenotypic hybrids (birds with plumage that is similar to both species) have mated and produced fertile offspring. It is believed, however, that this becomes less likely when the individuals are from different migrations and are not hybrids, as they have a greater chance of failing during the courtships.