䴓属属

䴓科只有䴓属（Sitta）一个属，过去曾归为本科的红翅旋壁雀（Trichodroma muraria）现在被单独列为旋壁雀科（Tichodromadidae）。

• 常见的䴓属鸟类包括：
• 白胸䴓 Sitta carolinensis
• 茶腹䴓 Sitta europea
• 丽䴓 Sitta formosa
• 绒额䴓 Sitta frontalis
• 阿尔及利亚䴓 Sitta ledanti
• 喜山䴓 Sitta leucopsis
• 巨䴓 Sitta magna
• 淡紫䴓 Sitta solangiae
• 黑头䴓 Sitta villosa
• 滇䴓 Sitta yunnanensis

The nuthatches constitute a genus, Sitta, of small passerine birds belonging to the family Sittidae. Characterised by large heads, short tails, and powerful bills and feet, nuthatches advertise their territory using loud, simple songs. Most species exhibit grey or bluish upper parts and a black eye stripe.

Most nuthatches breed in the temperate or montane woodlands of the Northern Hemisphere, although two species have adapted to rocky habitats in the warmer and drier regions of Eurasia. The greatest diversity, though, is in South Asia, and similarities between the species have made identifying distinct species difficult. All members of this genus nest in holes or crevices; most are nonmigratory and live in their habitat year-round, although the North American red-breasted nuthatch migrates to warmer regions during the winter. A few nuthatch species have restricted ranges and face threats from deforestation.

Nuthatches are omnivorous, eating mostly insects, nuts, and seeds. They forage for insects hidden in or under bark by climbing along tree trunks and branches, sometimes upside down. They forage within their territories when breeding, but they may join mixed feeding flocks at other times.

Their habit of wedging a large food item in a crevice and then hacking at it with their strong bills gives this group its English name.

Taxonomy

The nuthatch family, Sittidae, was described by René-Primevère Lesson in 1828.

Sometimes, the wallcreeper (Tichodroma muraria), which is restricted to the mountains of southern Eurasia, was placed in the same family as the nuthatches, but in a separate subfamily "Tichodromadinae", in which case the nuthatches were classified in the subfamily "Sittinae", but the wallcreeper is now placed in a separate family, the Tichodromadidae.

Description

Nuthatches are compact birds with short legs, compressed wings, and square, 12-feathered tails. They have long, sturdy, pointed bills and strong toes with long claws. Nuthatches have blue-grey backs (violet-blue in some Asian species, which also have red or yellow bills) and white underparts, which are variably tinted with buff, orange, rufous, or lilac. Although head markings vary between species, a long black eye stripe, with contrasting white supercilium, dark forehead, and blackish cap is common.

Species

The species diversity for the Sittidae is greatest in southern Asia (possibly the original home of this family), where about 15 species occur, but it has representatives across much of the Northern Hemisphere. The currently recognised nuthatch species are tabulated below.

Distribution and habitat

Members of the nuthatch family live in most of North America and Europe and throughout Asia south to the Wallace Line. They are sparsely represented in Africa; one species lives in a small area of northeastern Algeria and a population of the Eurasian nuthatch subspecies, S. e. hispaniensis, lives in the mountains of Morocco. Most species are resident year-round.

Behaviour

Nesting, breeding, and survival

All nuthatches nest in cavities; except for the two species of rock nuthatches, all use tree holes, making a simple cup lined with soft materials on which to rest eggs. In some species, the lining consists of small, woody objects such as bark flakes and seed husks, while in others, it includes the moss, grass, hair, and feathers typical of passerine birds.

Members of the red-breasted nuthatch superspecies excavate their own tree holes, although most other nuthatches use natural holes or old woodpecker nests.

Conservation status

Some nuthatches, such as the Eurasian nuthatch and the North American species, have extensive ranges and large populations, and few conservation problems, although locally they may be affected by woodland fragmentation. In contrast, some of the more restricted species face severe pressures.

The endangered white-browed nuthatch is found in only the Mount Victoria area of Burma, where forest up to 2,000 m (6,600 ft) above sea level has been almost totally cleared and habitat between 2,000 and 2,500 m (6,600 and 8,200 ft) is heavily degraded.