Nuthatch
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The nuthatches () constitute a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
, ''Sitta'', of small
passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s 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. Most nuthatches breed in the temperate or montane woodlands of the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, although two species have adapted to rocky habitats in the warmer and drier regions of
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
. 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 Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by ...
and live in their habitat year-round, although the
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
n
red-breasted nuthatch The red-breasted nuthatch (''Sitta canadensis'') 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, wh ...
migrates to warmer regions during the winter. A few nuthatch species have restricted ranges and face threats from
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
. Nuthatches are
omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
, eating mostly
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s, nuts, and
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s. 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 The wallcreeper (''Tichodroma muraria'') is a small passerine bird found throughout the high mountains of the Palearctic from southern Europe to central China. It is the only extant member of both the genus ''Tichodroma'' and the family Tichodr ...
(''Tichodroma muraria''), which is restricted to the mountains of southern Eurasia, is placed in the same family as the nuthatches, but in a separate subfamily "Tichodromadinae", in which case the nuthatches are classified in the subfamily "Sittinae". However, it is more often placed in a separate family, the Tichodromadidae.Snow & Perrins (1998) pp. 1408 The wallcreeper is intermediate in its morphology between the nuthatches and the
treecreeper The treecreepers are a family, Certhiidae, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains eleven species in two genera, '' Certhia'' and '' Salpornis''. Their plumage ...
s, but its appearance, the texture of its plumage, and the shape and pattern of its tail suggest that it is closer to the former
taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
. The nuthatch vanga of
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...
(formerly known as the coral-billed nuthatch) and the
sittella The sittellas are a family, Neosittidae, of small passerine birds found only in Australasia. They resemble nuthatches, but whilst they were considered to be in that family for many years they are now afforded their own family. They do not migrat ...
s from
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
and
New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torres ...
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 Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
to fill an
ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...
.Harrap & Quinn (1996) pp. 16–17 "Family Introduction" The nuthatches' closest relatives, other than the wallcreeper, are the
treecreeper The treecreepers are a family, Certhiidae, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains eleven species in two genera, '' Certhia'' and '' Salpornis''. Their plumage ...
s, and the two (or three) families are sometimes placed in a larger grouping with the
wren Wrens are a family of brown passerine birds in the predominantly New World family Troglodytidae. The family includes 88 species divided into 19 genera. Only the Eurasian wren occurs in the Old World, where, in Anglophone regions, it is commonl ...
s and
gnatcatcher The Gnatcatchers are a family of small passerine birds called Polioptilidae. The 21 species occur in North and South America (except for the far south and the high Andean regions). Most species of this mainly tropical and subtropical group are re ...
s. This
superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...
, the
Certhioidea Certhioidea is a superfamily belonging to the infraorder Passerida containing wrens and their allies. It was proposed in 2004 by Cracraft and colleagues to house a clade of four families that were removed from the superfamily Sylvioidea. Cla ...
, is proposed on
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...
studies using
mitochondria A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...
l and
nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...
DNA, and was created to cover a clade of (four or) five families removed from a larger grouping of passerine birds, the
Sylvioidea Sylvioidea is a superfamily of passerine birds, one of at least three major clades within the Passerida along with the Muscicapoidea and Passeroidea. It contains about 1300 species including the Old World warblers, Old World babblers, swallows ...
.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.


Genus name

The nuthatches are all in the genus ''Sitta''
Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
, 1758, a name derived from : síttē,
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
for this bird. The English term ''nuthatch'' refers to the propensity of some species to wedge a large insect or seed in a crack and hack at it with their strong bills.


Species boundaries

Species boundaries in the nuthatches are difficult to define. The red-breasted nuthatch,
Corsican nuthatch The Corsican nuthatch (''Sitta whiteheadi'') is a species of bird in the nuthatch family Sittidae. It is a relatively small nuthatch, measuring about in overall length. The are bluish gray, the grayish white. The male is distinguished from th ...
and
Chinese nuthatch The Chinese nuthatch or snowy-browed nuthatch (''Sitta villosa'') is a species of bird in the family Sittidae. It is a small nuthatch, measuring in length. The are blue-gray and the from a dull buff-grayish to a cinnamon-orange; the cheeks ar ...
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 normally split into threeHarrap & Quinn (1996) pp. 12–13 "Species limits" and comprise a superspecies along with the Krüper's and
Algerian nuthatch The Algerian nuthatch or Kabyle nuthatch (''Sitta ledanti''), in the local dialect (''Nsayeb di Zerqa'') is a species of bird in the nuthatch family Sittidae. It is a medium-sized nuthatch, measuring between and . The are bluish gray. The male ...
. Unusually for nuthatches, all five species excavate their own nests. The
Eurasian Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipela ...
, chestnut-vented,
Kashmir Kashmir () is the northernmost geographical region of the Indian subcontinent. Until the mid-19th century, the term "Kashmir" denoted only the Kashmir Valley between the Great Himalayas and the Pir Panjal Range. Today, the term encompas ...
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 Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...
, the Burmese nuthatch, ''Sitta neglecta'', found in southeast Asia, and the chestnut-bellied nuthatch ''sensu stricto'', ''S. cinnamoventris'', which occurs in the
Himalayas The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 10 ...
. 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 The British Ornithologists' Union (BOU) aims to encourage the study of birds ("ornithology") and around the world, in order to understand their biology and to aid their conservation. The BOU was founded in 1858 by Professor Alfred Newton, Henr ...
. 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 nuthatch The sulphur-billed nuthatch (''Sitta oenochlamys'') is a species of bird in the family Sittidae. It is endemic to the Philippines. Its natural habitats are subtropical or tropical moist lowland forest and subtropical or tropical moist monta ...
es) to a new genus, create a third genus for the
blue nuthatch The blue nuthatch (''Sitta azurea'') is a bird species in the nuthatch family Sittidae. It is a medium-sized nuthatch, measuring in length. The species, which shows slight sexual dimorphism, has dramatic coloration unlike any other member of i ...
, and possibly a fourth for the
beautiful nuthatch The beautiful nuthatch (''Sitta formosa'') is a bird species in the family Sittidae, collectively known as nuthatches. It is a large nuthatch, measuring in length, that is not sexually dimorphic. Its coloration and markings are dramatic, the u ...
. The fossil record for this group appears to be restricted to a foot bone of an early
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
bird from
Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total l ...
which has been identified as an extinct representative of the climbing Certhioidea, a
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
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.


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 The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head.Dunn and Alderfer (2006), p. 10 Also k ...
, 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 The brown-headed nuthatch (''Sitta pusilla'') 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 stud ...
and the
pygmy nuthatch The pygmy nuthatch (''Sitta pygmaea'') is a tiny songbird, about long and about 10 grams in weight. Description Measurements: * Length: * Weight: * Wingspan: It ranges from southern British Columbia south through various discontinu ...
, both around in length and about .Harrap & Quinn (1996) pp. 130–133 "Brown-headed 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 The black-capped chickadee (''Poecile atricapillus'') is a small, non-migratory, North American songbird that lives in deciduous and mixed forests. It is a passerine bird in the tit family, the Paridae. It is the state bird of Massachusetts and ...
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.


Distribution and habitat

Members of the nuthatch family live in most of North America and Europe and throughout Asia down to the
Wallace Line The Wallace Line or Wallace's Line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by English biologist Thomas Henry Huxley that separates the biogeographical realms of Asia and Wallacea, a trans ...
. Nuthatches are sparsely represented in Africa; one species lives in a small area of northeastern AlgeriaSnow & Perrins (1998) pp. 1400–1401 "Algerian Nuthatch" and a population of the Eurasian nuthatch subspecies, ''S. e. hispaniensis'', lives in the mountains of
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to A ...
.Snow & Perrins (1998) pp. 1402–1404 "Nuthatch" Most species are resident year-round. The only significant migrant is the red-breasted nuthatch, which winters widely across North America, deserting the northernmost parts of its breeding range in Canada; it has been recorded as a vagrant in
Bermuda ) , anthem = "God Save the King" , song_type = National song , song = "Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , es ...
,
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
and England. Most nuthatches are woodland birds and the majority are found in
conifer Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...
ous or other
evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...
forests, although each species has a preference for a particular tree type. The strength of the association varies from the Corsican nuthatch, which is closely linked with
Corsican pine ''Pinus nigra'', the Austrian pine or black pine, is a moderately variable species of pine, occurring across Southern Europe from the Iberian Peninsula to the eastern Mediterranean, on the Anatolian peninsula of Turkey, Corsica and Cyprus, as wel ...
, to the catholic habitat of the Eurasian nuthatch, which prefers
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
or mixed woods but breeds in coniferous forests in the north of its extensive range.Snow & Perrins (1998) pp. 1399–1400 "Corsican nuthatch" However, the two species of rock nuthatches are not strongly tied to woodlands: they breed on rocky slopes or cliffs, although both move into wooded areas when not breeding.Snow & Perrins (1998) pp. 1404–1406 "Eastern Rock Nuthatch" In parts of Asia where several species occur in the same geographic region, there is often an altitudinal separation in their preferred habitats. Nuthatches prefer a fairly temperate climate; northern species live near sea level whereas those further south are found in cooler highland habitats. Eurasian and red-breasted nuthatches are lowland birds in the north of their extensive ranges, but breed in the mountains further south; for example, the Eurasian nuthatch, which breeds where the July temperature range is , is found near sea level in Northern Europe, but between altitude in Morocco. The velvet-fronted nuthatch is the sole member of the family which prefers tropical lowland forests.


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 Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar regions ...
nests. Several species reduce the size of the entrance hole and seal up cracks with mud. The red-breasted nuthatch makes the nest secure by daubing sticky conifer
resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on nat ...
globules around the entrance, the male applying the resin outside and the female inside. The resin may deter predators or competitors (the resident birds avoid the resin by diving straight through the entrance hole). The white-breasted nuthatch smears
blister beetle Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many are conspicuous and some are aposematically colored, announcing their ...
s around the entrance to its nest, and it has been suggested that the unpleasant smell from the crushed insects deters
squirrel Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. ...
s, its chief competitor for natural tree cavities. The western rock nuthatch builds an elaborate flask-shaped nest from mud, dung and hair or feathers, and decorates the nest's exterior and nearby crevices with feathers and insect wings. The nests are located in rock crevices, in caves, under cliff overhangs or on buildings. The eastern rock nuthatch builds a similar but less complex structure across the entrance to a cavity. Its nest can be quite small but may weigh up to 32  kg (70  lb). This species will also nest in river banks or tree holes and will enlarge its nest hole if it the cavity is too small. Nuthatches are
monogamous Monogamy ( ) is a form of dyadic relationship in which an individual has only one partner during their lifetime. Alternately, only one partner at any one time ( serial monogamy) — as compared to the various forms of non-monogamy (e.g., pol ...
. The female produces eggs that are white with red or yellow markings; the clutch size varies, tending to be larger for northern species. The eggs are incubated for 12 to 18 days by the female alone, or by both parents, depending on the species. The
altricial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...
(naked and helpless) chicks take between 21 and 27 days to fledge.Snow & Perrins (1998) pp. 1406–1407 "Rock Nuthatch"Snow & Perrins (1998) p. 1398 "Nuthatch: Family Sittidae" Both parents feed the young, and in the case of two American species, brown-headed and pygmy, helper males from the previous brood may assist the parents in feeding. For the few species on which data are available, the average nuthatch lifespan in the wild is between 2 and 3.5 years, although ages of up to 10 years have been recorded. The Eurasian nuthatch has an adult annual
survival rate Survival rate is a part of survival analysis. It is the proportion of people in a study or treatment group still alive at a given period of time after diagnosis. It is a method of describing prognosis in certain disease conditions, and can be use ...
of 53% and the male Corsican nuthatch 61.6%. Nuthatches and other small woodland birds share the same predators:
accipiter ''Accipiter'' is a genus of birds of prey in the family Accipitridae. With 51 recognized species it is the most diverse genus in its family. Most species are called goshawks or sparrowhawks, although almost all New World species (excepting th ...
s,
owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...
s, squirrels and woodpeckers. An American study showed that nuthatch responses to predators may be linked to reproductive strategies. It measured the willingness of males of two species to feed incubating females on the nest when presented with models of a
sharp-shinned hawk The sharp-shinned hawk (''Accipiter striatus'') is a small hawk, with males being the smallest hawks in the United States and Canada, but with the species averaging larger than some Neotropical species, such as the tiny hawk. The taxonomy is fa ...
, which hunts adult nuthatches, or a
house wren The house wren (''Troglodytes aedon'') is a very small bird of the wren family, Troglodytidae. It occurs from Canada to southernmost South America, and is thus the most widely distributed native bird in the Americas. It occurs in most suburban ar ...
, which destroys eggs. The white-breasted nuthatch is shorter-lived than the red-breasted nuthatch, but has more young, and was found to respond more strongly to the egg predator, whereas the red-breasted showed greater concern with the hawk. This supports the theory that longer-lived species benefit from adult survival and future breeding opportunities while birds with shorter life spans place more value on the survival of their larger broods. Cold can be a problem for small birds that do not migrate.
Communal roosting Communal roosting is an animal behavior where a group of individuals, typically of the same species, congregate in an area for a few hours based on an external signal and will return to the same site with the reappearance of the signal. Environment ...
in tight huddles can help conserve heat and several nuthatch species employ it—up to 170 pygmy nuthatches have been seen in a single roost. The pygmy nuthatch is able to lower its body temperature when roosting, conserving energy through
hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
and a lowered
metabolic rate Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
.


Feeding

Nuthatches forage along tree trunks and branches and are members of the same
feeding guild A guild (or ecological guild) is any group of species that exploit the same resources, or that exploit different resources in related ways. It is not necessary that the species within a guild occupy the same, or even similar, ecological niches. D ...
as woodpeckers. Unlike woodpeckers and
treecreepers The treecreepers are a family, Certhiidae, of small passerine birds, widespread in wooded regions of the Northern Hemisphere and sub-Saharan Africa. The family contains eleven species in two genera, ''Certhia'' and ''Salpornis''. Their plumage i ...
, however, they do not use their tails for additional support, relying instead on their strong legs and feet to progress in jerky hops. They are able to descend head-first and hang upside-down beneath twigs and branches. Krüper's nuthatch can even stretch downward from an upside-down position to drink water from leaves without touching the ground. Rock nuthatches forage with a similar technique to the woodland species, but seek food on rock faces and sometimes buildings. When breeding, a pair of nuthatches will only feed within their territory, but at other times will associate with passing tits or join
mixed-species feeding flock A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species that join each other and move together while foraging. These are ...
s.
Insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...
s and other
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s are a major portion of the nuthatch diet, especially during the breeding season, when they rely almost exclusively on live prey, but most species also eat seeds during the winter, when invertebrates are less readily available. Larger food items, such as big insects,
snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class ...
s,
acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera '' Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and b ...
s or seeds may be wedged into cracks and pounded with the bird's strong bill. Unusually for a bird, the brown-headed nuthatch uses a piece of tree bark as a lever to pry up other bark flakes to look for food; the bark tool may then be carried from tree to tree or used to cover a seed
cache Cache, caching, or caché may refer to: Places United States * Cache, Idaho, an unincorporated community * Cache, Illinois, an unincorporated community * Cache, Oklahoma, a city in Comanche County * Cache, Utah, Cache County, Utah * Cache County ...
. All nuthatches appear to store food, especially seeds, in tree crevices, in the ground, under small stones, or behind bark flakes, and these caches are remembered for as long as 30 days. Similarly, the rock nuthatches wedge snails into suitable crevices for consumption in times of need. European nuthatches have been found to avoid using their caches during benign conditions in order to save them for harsher times.


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 An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
white-browed nuthatch is found only in the Mount Victoria area of Burma, where forest up to above sea level has been almost totally cleared and habitat between is heavily degraded. Nearly 12,000 people live in the Natma Taung
national park A national park is a natural park in use for conservation purposes, created and protected by national governments. Often it is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual ...
which includes Mount Victoria, and their fires and traps add to the pressure on the nuthatch. The population of the white-browed nuthatch, estimated at only a few thousand, is decreasing, and no conservation measures are in place. The Algerian nuthatch is found in only four areas of Algeria, and it is possible that the total population does not exceed 1,000 birds. Fire, erosion, and grazing and disturbance by livestock have reduced the quality of the habitat, despite its location in the Taza National Park. Deforestation has also caused population declines for the vulnerable Yunnan and yellow-billed nuthatches. The Yunnan nuthatch can cope with some tree loss, since it prefers open pine woodland, but although still locally common, it has disappeared from several of the areas in which it was recorded in the early 20th century. The threat to yellow-billed is particularly acute on Hainan, where more than 70% of the woodland has been lost in the past 50 years due to shifting cultivation and the use of wood for fuel during Chinese government re-settlement programmes. Krüper's nuthatch is threatened by urbanisation and development in and around mature coniferous forests, particularly in the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...
coastal areas where the species was once numerous. A law promoting tourism came into force in Turkey in 2003, further exacerbating the threats to their habitat. The law reduced bureaucracy and made it easier for developers to build tourism facilities and summer houses in the coastal zone where woodland loss is a growing problem for the nuthatch.


Notes


References

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External links


Oriental Bird Images
{{Featured article Nuthatches Sittidae Taxa named by René Lesson