Bewick's Wren

Identificazione

The Bewick's wren has an average length of 5.1 inches (13 cm) an average weight of 0.3 to 0.4 ounces (8–12 g), and a wingspan of 18 cm. Its plumage is brown on top and light grey underneath, with a white stripe above each eye. Its beak is long, slender, and slightly curved. Its most distinctive feature is its long tail with black bars and white corners. It moves its tail around frequently, making this feature even more obvious for observers.<p>Juveniles look similar to adults, with only a few key differences. Their beaks are usually shorter and stockier. In addition, their underbelly might feature some faint speckling. Males and females are very similar in appearance.<p>Bewick's wrens, like many wrens, are very vocal. Both females and males make short calls while foraging and both use a harsh scolding call when agitated. Males also sing in order to attract mates and protect their territory. The song is broken into two or three individual parts; one individual male may exhibit up to twenty-two different variations on the song pattern, and may even throw in a little ventriloquism to vary it even further. A male wren learns its song from neighboring males, so its song will be different from its father's.<p>Geographic differences have been observed in the appearance of the Bewick's wren. Eastern populations, prior to their decline, were described as being more colorful, such as having a reddish tint to its brown feathers. Pacific populations are described as being darker in appearance, while populations in the Southwest are described as having a grayer plumage.<p>Geographic differences have also been noted in the song of Bewick's wrens. Each regional population of Bewick's wrens have distinctive vocalizations, in particular their call notes. Pacific populations sing notably more complicated songs than Southwestern populations. Eastern populations were also noted to be excellent singers.

Tassonomia

In 1827, the American ornithologist John James Audubon included an illustration of Bewick's wren under the binomial name Troglodytes bewickii in his The Birds of America. In the companion Ornithological Biography, published four years later, Audubon explained that he had shot the specimen near St. Francisville, Louisiana in 1821 and had chosen the specific epithet bewickii in honour of his friend the engraver Thomas Bewick. Bewick's wren is now the only species placed in the genus Thryomanes that was introduced by the English zoologist Philip Sclater in 1862.<p>The Socorro wren was formerly also placed in Thryomanes, but is now known to be a close relative of the house wren complex, as indicated by biogeography and mtDNA NADH dehydrogenase subunit 2 sequence analysis, whereas Thryomanes seems not too distant from the Carolina wren.<p>Fifteen subspecies are recognised of which two are now extinct. Subspecies can be distinguished by the small differences in the color of the dorsal feathers but this can be difficult for museum specimens as the colors tend to change after a few years of storage.

Nome scientifico

Thryomanes bewickii

Autorità

(Audubon, 1827)

Ordine

Passeriformi

Famiglia

Troglodytidae

Genere

Thryomanes

Areale e habitat

The Bewick's wren once had a range that extended throughout much of the United States and Mexico and parts of Canada. It used to be fairly common in the Midwest and in the Appalachian Mountains, but it is now extremely rare east of the Mississippi River. It is still found along the Pacific Coast from Baja California to British Columbia, in Mexico, and in a significant portion of the Southwest, including Texas, Arizona, New Mexico, and Oklahoma. Western populations do not tend to migrate. Eastern populations, prior to their decline, used to migrate from its northern range to the Gulf Coast.<p>The preferred habitat of the Bewick's wren is that of arid open woodlands and brush-filled areas such as hillsides and uplands, but will reside in humid areas locally (Subtropical and Temperate zones). They are more common than house wrens in drier habitats, such as those found in the Southwest. In California, Bewick's wrens inhabit a shrubland area called chaparral.

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione