Passero cinguettante

Identificazione

Throughout the year, adults are gray below and an orangish-rust color above. Adults in alternate (breeding) plumage have a reddish cap, a nearly white supercilium, and a black trans-ocular line (running through the eye). Adults in basic (nonbreeding) plumage are less prominently marked, with a brownish cap, a dusky eyebrow, and a dark eye-line.<p>Juvenile chipping sparrows are prominently streaked below. Like non-breeding adults, they show a dark eye-line, extending both in front of and behind the eye. The brownish cap and dusky eyebrow are variable but generally obscure in juveniles.<p>Measurements:<p>The song is a trill that varies considerably among birds within any particular region. Two broad classes of variation in the song of the chipping sparrow are the fast trill and the slow trill. Individual elements in the fast trill are run together about twice as fast as in the slow trill; the fast trill sounds like a buzz or like someone snoring, whereas the slow trill sounds like rapid finger-tapping. Individual elements in the trill are very similar to a high pitch chi chi chi call.<p>The flight call of the chipping sparrow is heard year-round. Its flight call is piercing and pure-tone, lasting about 50 milliseconds. It starts out around 9 kHz, then falls to 7 kHz, then rises again to 9 kHz. The flight call may be transliterated as seen? Chipping sparrows migrate by night, and their flight calls are a characteristic sound of the night sky in spring and fall in the United States. In the southern Rockies and eastern Great Plains, the chipping sparrow appears to be the most common nocturnal migrant, judged by the number of flight calls detected per hour. On typical nights in August in this region, chipping sparrows may be heard at a rate of 15 flight calls per hour. On better-than-average nights, chipping sparrows occur at a rate of 60 flight calls per hour, and on exceptional nights chipping sparrows' flight calls are heard more than 200 times per hour.

Tassonomia

Chipping sparrows vary across their extensive North American range. There is minor geographic variation in appearance, and there is significant geographic variation in behavior. Ornithologists often divide the chipping sparrow into two major groups: the eastern chipping sparrow and the western chipping sparrow. However, there is additional plumage and behavioral variation within the western group.<p>At least two subspecies of chipping sparrows occur in western North America. The widespread Spizella passerina arizonae is associated with mountains and arid habitats of the western interior. A Pacific slope population constitutes subspecies S. p. stridula. Although these two races are both western, and are often lumped together as the western chipping sparrow, they do not necessarily form a single entity that stands apart from the eastern chipping sparrow (S. p. passerina).

Nome scientifico

Spizella passerina

Autorità

(Bechstein, 1798)

Ordine

Passeriformi

Famiglia

Passerellidae

Genere

Spizella

Areale e habitat

Migrazione

Complete migrants

Conservazione

Tendenza della popolazione

declining