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. However, the greatest diversity is in Southern Asia, and similarities between the species have made it difficult to identify distinct species. All members of this genus nest in holes or crevices. Most species are non-migratory 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. Lesson used the French Sittées rather than the Latin Sittidae.
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". However, the wallcreeper is now placed in a separate family, the Tichodromadidae.Snow & Perrins (1998) pp. 1408 The wallcreeper is intermediate in its morphology between the nuthatches and the treecreepers, but its appearance, the texture of its plumage, and the shape and pattern of its tail suggest that it is closer to the nuthatches.
The next closest relatives to nuthatches after the wallcreeper, are the treecreepers (Certhiidae) and spotted creepers (Salpornithidae), with these families placed in a larger grouping with the wrens (Troglodytidae) and gnatcatchers (Polioptilidae). This superfamily, the Certhioidea, is proposed on phylogenetic studies using mitochondrial and nuclear DNA, and was created to cover a clade of families removed from a larger grouping of passerine birds, the Sylvioidea.Cracraft, J.; Barker, F. Keith; Braun, M. J.; Harshman, J.; Dyke, G.; Feinstein, J.; Stanley, S.; Cibois, A.; Schikler, P.; Beresford, P.; García-Moreno, J.; Sorenson, M. D.; Yuri, T.; Mindell. D. P. (2004) "Phylogenetic relationships among modern birds (Neornithes): Toward an avian tree of life." pp. 468–489 in Assembling the tree of life (J. Cracraft and M. J. Donoghue, eds.). Oxford University Press, New York.
The nuthatch vanga of Madagascar (formerly known as the coral-billed nuthatch) and the sittellas from Australia and New Guinea were once placed in the nuthatch family because of similarities in appearance and lifestyle, but they are not closely related. The resemblances arose via convergent evolution to fill an ecological niche.Harrap & Quinn (1996) pp. 16–17 "Family Introduction"
Genus name The nuthatches are all in the genus Sitta Linnaeus, 1758, a name derived from : , Ancient Greek for this bird.
The English term nuthatch refers to the propensity of some species to wedge nuts or other large seeds in a crack and hack at it with their strong bills.
Species boundaries In the 20th century and earlier, species boundaries in the nuthatches were sometimes difficult to define. The red-breasted nuthatch, Corsican nuthatch and Chinese nuthatch have breeding ranges separated by thousands of kilometres, but are similar in habitat preference, appearance and song. They were formerly considered to be one species, but are now split into threeHarrap & Quinn (1996) pp. 12–13 "Species limits" and comprise a superspecies along with Krüper's and Algerian nuthatches. Unusually for nuthatches, all five species excavate their own nests.
The Eurasian, chestnut-vented, Kashmir and chestnut-bellied nuthatches form another superspecies and replace each other geographically across Asia. They are currently considered to be four separate species, but the south Asian forms were once believed to be a subspecies of the Eurasian nuthatch.Harrap & Quinn (1996) pp. 109–114 "Eurasian Nuthatch" A recent change in this taxonomy is a split of the chestnut-bellied nuthatch into three species, namely the Indian nuthatch, Sitta castanea, found south of the Ganges, the Burmese nuthatch, Sitta neglecta, found in southeast Asia, and the chestnut-bellied nuthatch sensu stricto, S. cinnamoventris, which occurs in the Himalayas. Mitochondrial DNA studies have demonstrated that the white-breasted northern subspecies of Eurasian nuthatch, S. (europea) arctica, is distinctive, and also a possible candidate for full species status. This split has been accepted by the British Ornithologists' Union.
A 2006 review of Asian nuthatches suggested that there are still unresolved problems in nuthatch taxonomy and proposed splitting the genus Sitta. This suggestion would move the red- and yellow-billed south Asian species (velvet-fronted, yellow-billed and sulphur-billed nuthatches) to a new genus, create a third genus for the blue nuthatch, and possibly a fourth for the beautiful nuthatch.
The fossil record for this group appears to be restricted to a foot bone of an early Miocene bird from Bavaria which has been identified as an extinct representative of the climbing Certhioidea, a clade comprising the treecreepers, wallcreeper and nuthatches. It has been described as Certhiops rummeli. Two fossil species have been described in the genus Sitta: S. cuvieri Gervais, 1852 and S. senogalliensis Portis, 1888, but they probably do not belong to nuthatches.Jiří Mlíkovský, Cenozoic Birds of the World. Part 1:Europe , Prague, Ninox Press, 2002, 407 p., p. 252, 273
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. The sexes look similar, but may differ in underpart colouration, especially on the rear flanks and under the tail. Juveniles and first-year birds can be almost indistinguishable from adults.
The sizes of nuthatches vary, from the large giant nuthatch, at and ,Harrap & Quinn (1996) pp. 169–172 "Giant Nuthatch" to the small brown-headed nuthatch and the pygmy nuthatch, both around in length and about .Harrap & Quinn (1996) pp. 130–133 "Brown-headed Nuthatch" The eastern rock nuthatch subspecies Sitta tephronota dresseri, while not as long-bodied as the giant nuthatch, is the heaviest nuthatch at 42.7–55 g.Harrap & Quinn (1996) pp. 158–161 "Eastern Rock Nuthatch"
Nuthatches are very vocal, using an assortment of whistles, trills and calls. Their breeding songs tend to be simple and often identical to their contact calls but longer in duration. The red-breasted nuthatch, which coexists with the black-capped chickadee throughout much of its range, is able to understand the latter species' calls. The chickadee has subtle call variations that communicate information about the size and risk of potential predators. Many birds recognise the simple alarm calls produced by other species, but the red-breasted nuthatch is able to interpret the chickadees' detailed variations and to respond appropriately.
Species The species diversity for 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. Species in taxonomic sequenceCommon andscientific names Subspecies ImageDescriptionRange (population if known)White-cheeked nuthatchSitta leucopsis1 long, white cheeks, chin, throat, and underparts, upper parts mostly dark grey.western HimalayasHarrap & Quinn (1996) pp. 148–150 "White-cheeked Nuthatch"Przevalski's nuthatchSitta przewalskii1 long, white cheeks, chin, throat, and underparts, upper parts mostly dark grey.southeastern Tibet to western ChinaRasmussen, P.C., and J.C. Anderton. 2005. Birds of South Asia. The Ripley guide. Volume 2: attributes and status. Smithsonian Institution and Lynx Edicions, Washington D.C. and BarcelonaGiant nuthatchSitta magna2 long, greyish upper parts and whitish underparts.China, Burma, and Thailand.White-breasted nuthatchSitta carolinensis7 long, the white of the face completely surrounds the eye, face and the underparts are white, upper parts are mostly pale blue-grey.North America from southern Canada to MexicoHarrap & Quinn (1996) pp. 150–155 "White-breasted Nuthatch"Bull, John and Farrand, John Jr. The Audubon Society Field Guide to North American Birds, Eastern Region. Alfred A. Knopf, Inc. (1977) pp. 646–647 "White-breasted Nuthatch"Beautiful nuthatchSitta formosa1 long, black-backed with white streaking, bright blue upper back, rump and shoulders, dull orange underparts and paler face.Northeast India and Burma and locally in southern China and northern Southeast AsiaHarrap & Quinn (1996) pp. 172–173 "Beautiful Nuthatch"Blue nuthatchSitta azurea3 long, greyish upper parts and whitish underparts.Malaysia, Sumatra and JavaHarrap & Quinn (1996) pp. 168–169 "Blue Nuthatch"Velvet-fronted nuthatchSitta frontalis5 long, violet-blue above, with lavender cheeks, beige underparts and a whitish throat, bill is red, black patch on forehead.India and Sri Lanka through Southeast Asia to IndonesiaHarrap & Quinn (1996) pp. 161–164 "Velvet-fronted Nuthatch"Yellow-billed nuthatchSitta solangiae3 long, white underparts, bluish upper parts, yellow beak.Vietnam and Hainan Island, ChinaHarrap & Quinn (1996) pp. 164–165 "Yellow-billed Nuthatch"Sulphur-billed nuthatchSitta oenochlamys6 long, pinkish underparts, yellow beak, bluish upper parts.Endemic to the PhilippinesHarrap & Quinn (1996) pp. 165–168 "Sulphur-billed Nuthatch"Pygmy nuthatchSitta pygmaea6 long, grey cap, blue-grey upper parts, whitish underparts, whitish spot on the nape.Western North America from British Columbia to southwest Mexico(2.3 million)Harrap & Quinn (1996) pp. 127–130 "Pygmy Nuthatch"Brown-headed nuthatchSitta pusilla1 long, brown cap with narrow black eye stripe and buff white cheeks, chin, and belly, wings are bluish-grey, small white spot at the nape of the neck.Endemic to the Southeastern United States(1.5 million)Bahama nuthatchSitta insularis1Very similar to brown-headed nuthatch, but has a darker eye stripe, much longer beak, shorter wings, and a different call than it.Endemic to Grand Bahama