Sturnella occidentale

Identificazione

Western meadowlark adults have yellow underparts with a black "V" on the breast and white flanks streaked with black. Their upper parts are mostly brown, but also have black streaks. These birds have long, pointed bills and their heads are striped with light brown and black bands.<p>Measurements:<p>These birds have a flute-like warbled song. These calls contrast with the simple, whistled call of the eastern meadowlark.

Tassonomia

The western meadowlark was formally described in 1844 by the American ornithologist John James Audubon under its current binomial name Sturnella neglecta. The specific epithet is from the Latin neglectus meaning "ignored", "overlooked", "neglected" or "disregarded". Audubon explained that although the account of the Lewis and Clark Expedition of 1803–1806 mentioned yellow larks, these had never been formally described. The type locality is Old Fort Union, North Dakota.<p>Despite having "lark" in their name due to their melodic song, they are not true Larks, as they are instead in the New World Blackbird family.<p>Two subspecies are recognised:<p>Western meadowlarks will occasionally interbreed with eastern meadowlarks where their ranges overlap; however, resulting young appear to have low fertility.

Nome scientifico

Sturnella neglecta

Autorità

Audubon, 1844

Ordine

Passeriformi

Famiglia

Icteridae

Genere

Sturnella

Areale e habitat

The breeding habitats of western meadowlarks are grasslands, prairies, pastures, and abandoned fields, all of which may be found across western and central North America, as far south as northern Mexico. In regions where their range overlaps with the eastern species, these birds prefer thinner, drier vegetation; the two type of birds generally do not interbreed but do defend territory against one another. Their nests are situated on the ground and are covered with a roof woven from grass. There may be more than one nesting female in a male's territory. Nests are sometimes destroyed by mowing operations with eggs and young in them.<p>Western meadowlarks are permanent residents throughout much of their range. Northern birds may migrate to the southern parts of their range; some birds also move east in the southern United States.<p>It has also been introduced to Hawaii to control insects, and is now found on the island of Kauai. Attempted introductions to other islands failed, likely due to the presence of the small Indian mongoose, which is absent from Kauai.

Migrazione

Complete migrants

Comportamento

The nest is built by the female soon after arrival on the breeding grounds. The nest is placed in a concealed location on the ground. It is variable in form and ranges from a simple cup to a partially roofed structure with a runway extending from the nest entrance. Eggs are laid at daily intervals. Incubation only begins after the last egg is laid. The eggs measure on average 28 mm × 21 mm (1.10 in × 0.83 in) and have brownish spots and blotches on a white ground. The eggs hatch over a period of one or two days after being incubated by the female for 13–15 days. The young are altricial and nearly naked; their eyes are closed until the 4th day. Only the female broods the chicks. The nestlings are almost exclusively fed insects. The male brings food to the nest which is then usually fed to the chicks by the female. The young fledge at 10-12 day but are only capable of sustained flight at around 21 days. The young receive parental care for around 2 weeks after fledging. A second brood is attempted.<p>The nests are parasitized by brown-headed cowbirds (Molothrus ater).<p>These birds forage on the ground or in low to semi-low vegetation. They sometimes search for food by probing with their bills. They mainly eat insects, although they will consume seeds and berries. In winter, these birds often feed in flocks.

Conservazione

Tendenza della popolazione

declining