The blue nuthatch (Sitta azurea) is a bird species in the nuthatch family Sittidae. It is a medium-sized nuthatch, measuring 13.5cm (5.3in) in length. The species, which shows slight sexual dimorphism, has dramatic coloration unlike any other member of its genus. Its head is black or blackish-blue dark blue upperparts close to purple with azure feathers. The wings are edged with black. The throat and chest are white or a washed buff color, contrasting with the upperparts and the belly of a very dark blue; the covert feathers are generally clear, blue-gray or purplish.
The blue nuthatch's ecology is poorly known, but it feeds on small invertebrates found on trees; reproduction takes place from April to June or July. It also forages in mixed-species flocks in larger groups. They can be found in the Malay Peninsula and on the islands of Sumatra and Java in Indonesia, where it inhabits subtropical or tropical moist lowland forest and subtropical or tropical moist montane forest above 900m (3,000ft) in altitude.
Three subspecies are recognized: S. a. expectata, S. a. nigriventer and S. a. azurea, which differ chiefly in the coloring of their mantles , chests and bellies. The species' closest relatives are the velvet-fronted nuthatch (S. frontalis), the yellow-billed nuthatch (S. solangiae) and the sulphur-billed nuthatch (S. oenochlamys). The population of the species has not been determined but the species appears to be at low risk of extinction because of the extent of its distribution. It has been classified as of least concern by the International Union for Conservation of Nature.
Taxonomy
The blue nuthatch was first described in 1830 under its current binomial name, Sitta azurea, by the French naturalist René Primevère Lesson (1794–1849).[3][4]Sitta is derived from the Ancient Greek name for nuthatches, σίττη, sittē.[5][6] "Nuthatch", first recorded in 1350, is derived from "nut" and a word probably related to "hack", since these birds hack at nuts they have wedged into crevices.[7] The genus may be further divided into seven subgenera,[fn. 1] of which the blue nuthatch is placed alone in Poecilositta(Buturlin 1916).[8]
The nuthatches constitute a genus, Sitta, of small passerine birds in the familySittidae,[9] typified by short, compressed wings and short, square 12-feathered tails, a compact body, longish pointed bills , strong toes with long claws, and behaviorally, by their unique head-first manner of descending tree trunks. Most nuthatches have gray or bluish upperparts and a black eyestripe.[10] In 2006, ornithologist Edward C. Dickinson Proposed splitting Sitta in multiple genera on the basis of distinct morphological traits. He suggested as candidates the velvet-fronted nuthatch (Sitta frontalis) and the blue nuthatch, the morphology of which he describes as "rather aberrant ... in spite of a character trait (white edges to wing feathers) shared with Sitta formosa", and that doing so might, in turn, require the beautiful nuthatch (S. formosa) to be split off as well. He stated, however, that a molecular study would be warranted prior to any re-classification.[11][12]
In 2014, Eric Pasquet and colleagues published a phylogeny based on examination of nuclear and mitochondrial DNA of 21 nuthatch species.[fn. 2] The position of the blue nuthatch within the genus was not established with certainty, having a far lower correlation than many others in the model. Nevertheless, under the findings the species appears best represented by a clade comprising the velvet-fronted nuthatch and the sulphur-billed nuthatch (S. oenochlamys). These tropical Asian nuthatches are themselves a sister clade to one comprising the subgenus Sitta (Micrositta) (sometimes called the canadensis group), along with the brown-headed nuthatch (S. pusilla) and the pygmy nuthatch (S. pygmaea).[10][13]
Phylogenetic tree detail Nuthatch phylogenic detail according to Pasquet, et al. (2014):[10]
There are three recognized subspecies of the blue nuthatch.[14]
S. a. expectata(Hartert, 1914), described in 1914 by German ornithologist Ernst Hartert as Callisitta azurea expectata from a holotype taken in the Malay Peninsula's Semangko Pass in Pahang;[15] it is also found in Sumatra;[14]
S. a. nigriventer(Robinson & Kloss, 1919), described in 1919 by British zoologists Herbert Robinson and Cecil Kloss as Poliositta azurea nigriventer from a holotype taken at Mount Gede[16] in West Java, Indonesia.[14] British ornithologist William Swainson had described the subspecies under the name dendrophila flavipes in 1838, but the name was subsequently little used, and can be considered a nomen oblitum ("forgotten name");[17]
The blue nuthatch is a medium-sized nuthatch that has an average length of 13.5cm (5.3in). The weight is not known,[18] but may be comparable to the Algerian nuthatch (Sitta ledanti), which also measures 13.5cm (5.3in) long, and weighs between 16.6g (0.59oz) and 18g (0.63oz).[19] Its appearance differs significantly from all other nuthatches. All of its subspecies are broadly black and white[20] (especially when viewed in low-light conditions in which their dark blue coloring is not apparent) and have upper plumage shot through with dramatic notes of cobalt, azure and other lighter shades of blue, as well as grays and purples. The head is black, or blackish-blue with a broad, pale blue eye ring .[21][22]
The three subspecies vary predominantly in the coloring of their mantles, chests and bellies. The upperparts are dark blue at the mantle or purplish in some subspecies. The rectrices, which are the tail's flight feathers, are pale blue in the middle with a black border and contrast sharply with the dark areas of the coat. The throat and breast are white, or washed buff, especially in S. a. nigriventer. The belly and abdomen are blackish, contrasting with blue-gray or purplish coverts . The bill is lavender, slightly tinged with green, and black at the tip; the legs are a pale blue-gray and the claws are slate or black.[21][22]
The species displays no significant sexual dimorphism, but Japanese ornithologistNagamichi Kuroda describes the female as having slightly duller upperparts. Juveniles resemble adults, but have a duller crown and ear coverts, as well as a brown cast that does not cover their entire body. The belly is a dull black and the undertail coverts are variably edged creamy white. The juvenile's bill is blackish, with a pink base. Adults experience a partial moult before the breeding season (February–March for S. a. expectata; March–April for S. a. azurea) involving the throat, chest and mantle; a complete moult takes place after the breeding season (March–April and August in Java in Malaysia).[22]
The three subspecies of the blue nuthatch and their distinct morphological characteristics
Sitta azurea expectata - note the dark blue upper parts and azure coverts.
Sitta azurea azurea - note the purple upper parts and violet coverts.
Sitta azurea nigriventer - note the purplish-blue upper parts, blue coverts and buff-colored belly.
The species' vocalizations include a melodious tup or tip, a sudden whit, a thin hissing sit, and a fuller, harder, and more forceful chit. When excited, sit and chit notes are frequently given quickly and repetitively as a chi-chit, chit-chit-chit or chir-ri-rit, which can be prolonged, accelerated into staccato trilling tititititititik, or even becoming a rattling tr-r-r-r-r-r-t. Other calls include a thin, squeaking zhe and zhe-zhe, a squeaky toy-like nasal snieu or kneu, and a buzzy chirr-u. The vocal repertoire of the blue nuthatch is quite varied and is reminiscent of the velvet-fronted nuthatch and, to a lesser extent, the sulphur-billed nuthatch.[12]
Behavior and ecology
A blue nuthatch of subspecies S. a. expectata foraging in a tree, Fraser's Hill, Malaysia
The blue nuthatch feeds on arthropods, of which some have been particularly identified as common in its diet, including Trachypholis beetles, click beetles, Eumolpinaeleaf beetles, spiders, and moth caterpillars.[25] It typically forages for prey in the upper half of large trees, and occasionally in smaller trees.[24] While prospecting on tree trunks, the bird protects its corneas from falling bark and other debris by contracting the bare skin around its eyes – an adaptation apparently unique to the species.[26]
Breeding
The breeding of the species has not been extensively studied. The nest is made in a small tree hole in which it lays three to four dirty-white eggs, washed in lavender and densely speckled with reddish-brown and gray, that measure 19.3mm ×13.4mm (0.76in ×0.53in). In Peninsular Malaysia, juveniles just reaching maturity were observed in late June; on the island of Java, the breeding season takes place from April to July, and on Sumatra an adult feeding its young was observed on May 9.[24]
Predation
Little has been specifically reported on blue nuthatch predators, but one individual was seen to freeze during the passage of a prospecting black eagle (Ictinaetus malayensis).[23]
Distribution and habitat
A blue nuthatch on a tree trunk at Fraser's Hill, Malaysia.
This species lives in the Malay Peninsula (in extreme southern Thailand and northern Malaysia) and in Indonesia on the islands of Sumatra and Java.[1][14] In Malaysia, the species has been observed in Bukit Larut, in the state of Perak, in the Titiwangsa Mountains, in southern Hulu Langat, in the state of Selangor, as well as some isolated populations on the slopes of the massive Mount Benom in the state of Pahang, on Mount Tahan located at the Pahang-Kelantan border, on Mount Rabong in Kelantan and at Mount Padang in the Sultanate of Terengganu.[24]
In Sumatra, the bird is found throughout the Barisan Mountains, and has been observed in the Gayo Highlands of Aceh province, the Batak Highlands of northern Sumatra, and at Dempo in the south of the island.[24] In a 1918 expedition by Robinson and Kloss, they commented: "from the commencement of heavy jungle on the valley slopes up to about 8,000 feet on Korinchi Peak this strikingly coloured little Nuthatch was very common, feeding on tall tree trunks in parties of six or seven."[27]
The blue nuthatch is typically found on mountains, inhabiting subtropical or tropical moist lowland forest and subtropical or tropical moist montane forest. In Malaysia, it is found from 1,070m (3,510ft) to the highest point in the country at 2,186m (7,172ft). In Sumatra, the species has been reported at an altitudinal range of between 900m (3,000ft)[24] and 2,400m (7,900ft),[24] and on Java, between 915m (3,002ft) and 2,745m (9,006ft). Ornithologist John MacKinnon has reported some rare sightings at lower altitudes on the plains of Java.[28]
Threats and protection
The blue nuthatch is a common bird in Sumatra, including in the area of Kerinci Seblat National Park[27] and relatively common in Malaysia and Java.[24] It has a very wide distribution area, approaching 361,000km2 (139,000sqmi).[29] The population has not been rigorously estimated but is considered significant and at low risk, despite BirdLife International's observation that some decline is likely (but not as yet confirmed) due to known destruction and fragmentation of areas the species is known to inhabit.[29] The blue nuthatch is placed in the category of least concern by the International Union for Conservation of Nature.[1]
The 21 species are out of 24 recognized as making up the genus by Harrap and Quinn as of 1996. Of these, the study omitted the Indian nuthatch (Sitta castanea), the yellow-billed nuthatch (Sitta solangiae) and the white-browed nuthatch (Sitta victoriae). The International Ornithological Congress however recognized 28 species as of 2012, based on the elevation of four taxa from subspecies to full species status, including Przevalski's nuthatch (S. przewalskii) and three species from the europaea group.[10]
1 2 Wells, David R. (2007). "Passerines". In Christopher Helm (ed.). The Birds of the Thai-Malay Peninsula. Vol.2. Christopher Helm. pp.431–432. ISBN978-0-7136-6534-5.
↑ Becking, J. H. (1989). "Diets of Javanese birds". In Brill Archive (ed.). Henri Jacob Victor Sody (1892-1959): His Life and Work: a Biographical and Bibliographical Study. p.209.
↑ Curio, Eberhard (2001). "Wie Vögel ihr Auge schützen: Zur Arbeitsteilung von Oberlid, Unterlid und Nickhaut". Journal für Ornithologie (in German). 142 (3): 257–272. doi:10.1007/BF01651365. S2CID38854629.
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 upperparts and a black eye stripe.
The Eurasian nuthatch or wood nuthatch is a small passerine bird found throughout the Palearctic and in Europe. Like other nuthatches, it is a short-tailed bird with a long bill, blue-gray upperparts and a black eye-stripe. It is a vocal bird with a repeated loud dwip call. There are more than 20 subspecies in three main groups; birds in the west of the range have orange-buff underparts and a white throat, those in Russia have whitish underparts, and those in the east have a similar appearance to European birds, but lack the white throat.
The beautiful nuthatch is a bird species in the family Sittidae, collectively known as nuthatches. It is a large nuthatch, measuring 16.5 cm (6.5 in) in length, that is not sexually dimorphic. Its coloration and markings are dramatic, the upper parts being black and azure, streaked with white and pale blue on the head and lined with the same colors on the wing feathers. The underparts are orange, and the eyebrow and throat are ochre. An irregular, dark eyestripe highlights its eye. S. formosa's ecology is not fully described, but it is known to feed on small insects and larvae found on the trunks and epiphyte-covered branches of trees in its range. Reproduction takes place from April to May; the nest is placed in the hole of an oak, rhododendron, or other large tree. The nest is made of plant material and fur in which the bird typically lays four to six eggs.
The white-breasted nuthatch is a species of bird in the nuthatch family Sittidae. It is a medium-sized nuthatch, measuring approximately 15.5 cm (6.1 in) in length. Coloration varies somewhat along the species' range, but the upperparts are light blue-gray, with a black crown and nape in males, while females have a dark gray crown. The underparts are whitish, with a reddish tinge on the lower abdomen. Despite not being closely related, the white-breasted nuthatch and the white wagtail are very similar in plumage. The white-breasted nuthatch is a noisy bird. It has a nasal voice and often utters little cries or vocalizations, often composed of repetitions of small invariant whistles. In summer, it is an exclusively insectivorous bird, consuming a wide range of arthropods, but in winter its diet consists mainly of seeds. The nest is located in the cavity of a tree. The clutch consists of five to nine eggs, incubated for two weeks by the female, who is fed by the male. The two adults then feed the young until they fledge, and for a few weeks after that.
The red-breasted nuthatch is a small songbird. The adult has blue-grey upperparts with cinnamon underparts, a white throat and face with a black stripe through the eyes, a straight grey bill and a black crown. Its call, which has been likened to a tin trumpet, is high-pitched and nasal. It breeds in coniferous forests across Canada, Alaska and the northeastern and western United States. Though often a permanent resident, it regularly irrupts further south if its food supply fails. There are records of vagrants occurring as far south as the Gulf Coast and northern Mexico. It forages on the trunks and large branches of trees, often descending head first, sometimes catching insects in flight. It eats mainly insects and seeds, especially from conifers. It excavates its nest in dead wood, often close to the ground, smearing the entrance with pitch.
The velvet-fronted nuthatch is a small passerine bird in the nuthatch family Sittidae found in southern Asia from Nepal, India, Sri Lanka and Bangladesh east to south China and Indonesia. Like other nuthatches, it feeds on insects in the bark of trees, foraging on the trunks and branches and their strongly clawed toes allow them to climb down tree trunks or move on the undersides of horizontal branches. They are found in forests with good tree cover and are often found along with other species in mixed-species foraging flocks. Adult males can be told apart by the black stripe that runs behind and above the eyes. They have a rapid chipping call note. They breed in tree cavities and holes, often created by woodpeckers or barbets.
The black-naped monarch or black-naped blue flycatcher is a slim and agile passerine bird belonging to the family of monarch flycatchers found in southern and south-eastern Asia. They are sexually dimorphic, with the male having a distinctive black patch on the back of the head and a narrow black half collar ("necklace"), while the female is duller with olive brown wings and lacking the black markings on the head. They have a call that is similar to that of the Asian paradise flycatcher, and in tropical forest habitats, pairs may join mixed-species foraging flocks. Populations differ slightly in plumage colour and sizes.
The Corsican nuthatch is a species of bird in the nuthatch family Sittidae. It is a relatively small nuthatch, measuring about 12 cm (4.7 in) in overall length. The upperparts are bluish gray, the underparts grayish white. The male is distinguished from the female by its entirely black crown. The species is sedentary, territorial and not very shy. It often feeds high in Corsican pines, consuming mainly pine nuts, but also catching some flying insects. The breeding season takes place between April and May; the nest is placed in the trunk of an old pine, and the clutch has five to six eggs. The young fledge 22 to 24 days after hatching.
The Algerian nuthatch or Kabyle nuthatch, is a species of bird in the nuthatch family Sittidae. It is a medium-sized nuthatch, measuring between 11.5 cm (4.5 in) and 12.5 cm (4.9 in). The upperparts are bluish gray. The male can be distinguished from the female by the black front of its crown. The species is sedentary; it feeds on arthropods in summer and on seeds in winter. The breeding season takes place around May–June. The nest, built in a hole of tree, shelters a laying of three or four eggs, brooded by the female. The chicks are fed by both parents.
The brown-headed nuthatch is a small songbird endemic to pine forests throughout the Southeastern United States. Genetic analyses indicated low differentiation between northern and southern populations in Florida, but the study also found lower genetic diversity among south Florida populations that may be a result of the increased habitat fragmentation that was documented. The Bahama nuthatch was formerly considered a subspecies (S. p. insularis), has since been reclassified as its own separate species. Two recent studies assessing vocalizations in Bahama and continental nuthatch populations found important differences. One of the studies also demonstrated that continental and Bahama populations did not respond aggressively to calls of the other population. This type of call-response study is often used to help define cryptic species.
Krüper's nuthatch is a species of bird in the family Sittidae. It is a small to medium-sized nuthatch, measuring 12.5 centimetres (4.9 in) in length. The upperparts are blue-gray, with the front half of the crown black in adults of both sexes, but with a less marked in the female rear. The species has a black or gray eyestripe and a prominent white supercilium. The underparts are blue-gray in males and buff-gray in females, with a large, crescent-shaped rufous pectoral patch. The Krüper's nuthatch feeds on insects in the summer and seeds, especially pines, in the fall and winter. Breeding takes place between March and May, and the nest is usually placed in a tree hole. The clutch consists of five to seven eggs, incubated by the female and fed by the male. Both parents take part in feeding the young.
The chestnut-vented nuthatch is a species of bird in the nuthatch family Sittidae. It is a medium-sized nuthatch, measuring 12.5–14 cm (4.9–5.5 in) in length. The upperparts are a solid gray blue, with a markedly black loral stripe. The underparts are uniform gray to buff from the throat to belly, with brick red on the flanks. The undertail is white with a rufous border. The chestnut-vented nuthatch utters different kinds of calls, which can sometimes sound like a troglodyte alarm, and its song is a monotonous, stereotypical crackle, typically chichichichi. Its ecology is poorly known, but it probably feeds on small arthropods and seeds, and the breeding season begins between March and May. The nest is typically located in a hole in the trunk of a tree, and the clutch has two to five eggs.
The white-browed nuthatch, also known as the Victoria nuthatch, is a species of bird in the family Sittidae. It is a small nuthatch, measuring 11.5 cm (4.5 in) in length and without sexual dimorphism. Like many other nuthatches, the upperparts are gray-blue, contrasting with white underparts on the throat, cheeks, and breast and orange on the flanks, belly, and lower abdomen. Its white supercilium makes it easy to distinguish it from the white-tailed nuthatch, which is a close species in the systematic and geographical sense. Little is known about its ecology, but it feeds on small insects found among bark and lichens, and breeding occurs around April.
The Chinese nuthatch or snowy-browed nuthatch is a species of bird in the family Sittidae. It is a small nuthatch, measuring 11.5 cm (4.5 in) in length. The upperparts are blue-gray and the underparts from a dull buff-grayish to a cinnamon-orange; the cheeks are white. There is a marked sexual dimorphism: the adult male is distinguished by its very black crown, while that of the female is the same blue-grey as the back, or at most dark gray when the plumage is worn. In both sexes, a dark gray eyestripe extends in front of and behind the eye, topped by a clear white supercilium separating it from the crown. The song is variable, and composed of repetitions of small invariant whistles. The species feeds mainly on insects in summer and completes its diet with seeds and fruits. The nest is generally placed in the hole of a conifer. The pairs raises one brood per year, with five or six chicks.
The Yunnan nuthatch is a bird species in the nuthatch family Sittidae. It was first described by William Robert Ogilvie-Grant in 1900 based on a male holotype. It is a small nuthatch, measuring 12 centimetres (4.7 in) in length on average and weighs between 7.5 and 13 grams. The grey-blue upperparts contrast with the light, smooth, buffy lowerparts. It has a fine white eyebrow above a black eyestripe, which is distinct when the plumage is fresh, and exhibits a small degree of sexual dimorphism. A noisy bird, it produces simple, nasal sounds, sometimes in repetitive series.
The chestnut-bellied nuthatch belongs to the family Sittidae.
The Siberian nuthatch is a bird species of the family Sittidae. For a long time considered as a subspecies of the Eurasian nuthatch, it was clearly differentiated in 2006 on the basis of morphological and molecular characters. It is on average larger than the Eurasian nuthatch and also differs in some morphological features such as the shape of its bill, the size of its claws and the color of its underwing and outer rectrices. Its song has also been described as "distinctly different" from that of the Eurasian nuthatch, though without further clarification.
Przevalski's nuthatch, originally given the nomen nudumSitta eckloni, is a bird species in the family Sittidae, collectively known as nuthatches. Long regarded as a subspecies of the white-cheeked nuthatch, it nevertheless differs significantly in morphology and vocalizations. Both S. przewalskii and S. leucopsis have been regarded as closely related to the North American white-breasted nuthatch. It is a medium-sized nuthatch, measuring about 13 cm (5 in) in length. Its upper body is a dark gray-blue or slate color, becoming dark blue-black at the crown. The cheeks and throat are a white buff-orange, turning to a rich cinnamon on the underparts that intensifies in color on the sides of the breast. Vocalizations consist of alternating series of ascending whistles and short notes.
The giant nuthatch is a species of bird in the family Sittidae. It is the largest of the nuthatches, measuring 19.5 cm (7.7 in) in length. Its upperparts are bluish gray, with the front being light gray, contrasting with the darker rest of the back. The bird has two very thick black eyebrow lines and light gray underparts, with whitish cheeks and throat, and a belly more or less washed with buff and cinnamon. For a nuthatch, it has a long beak and tail. The female can be distinguished from the male by its duller eye features and its upperparts having less contrast between the crown, nape, and lower back. The calls are powerful and made up of repetitions of simple patterns. The species gleans its food from the trunks and branches of trees, especially pines, and feeds on insects and berries. It nests around March, in the hole of a tree and without masking the entrance, and the nest has about three young.
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