White-breasted nuthatch

The nuthatches are a genus, Sitta, of small passerine birds which derive their English name from the tendency of some species to wedge large insects or seeds into cracks, and then hack at them with their strong bills. Sitta is derived from , Ancient Greek for nuthatch, and carolinensis means "of Carolina" in Latin. The white-breasted nuthatch was first described by English ornithologist John Latham in his 1790 work, the Index Ornithologicus. German ornithologist Hans Edmund Wolters proposed the division of the genus Sitta into subgenera in 1975–1982. The white-breasted nuthatch is placed in Sitta (Leptositta) (Buturlin, 1916), alongside the white-cheeked nuthatch (S. leucopsis) and Przewalski's nuthatch (S. przewalskii). Nuthatch taxonomy is complex, with geographically separated species sometimes closely resembling each other. In appearance, the white-breasted nuthatch is similar to the white-cheeked nuthatch of the Himalayas, and was historically sometimes even considered to be conspecific with it. A study published in 2012 showed that four distinct lineages were genetically isolated from each other and could represent different species, recognizable by morphology and song. Molecular phylogenies published in 2014 and 2020 and including all main species' lineages within nuthatches concluded that the white-breasted nuthatch was more closely related to the giant nuthatch (S. magna) than to either white-cheeked or Przewalski's nuthatches; these latter two turned out to be basal in the family. The simplified cladogram below is based on the phylogenetic analysis by Päckert and colleagues (2020): |3= }} == Description ==

The white-breasted nuthatch is a medium-sized nuthatch, measuring about in length. Like other members of its genus, it has a large head, short tail, short wings, a powerful bill and strong feet; it is long, with a wingspan of and a weight of . The adult male of the nominate subspecies, S. c. carolinensis, has pale blue-gray , a glossy black cap ( of the head), and a black band on the upper back. The wing coverts and flight feathers are very dark gray with paler fringes, and the closed wing is pale gray and black, with a thin white wing bar. The face and the are white. The outer tail feathers are black with broad diagonal white bands across the outer three feathers, a feature readily visible in flight. Geographical variation The white-breasted nuthatch currently has seven accepted subspecies, although the differences are small and change gradually across the range. The subspecies are treated in two to four groups based on close similarities in morphology, habitat usage, and vocalizations. These groups cover eastern North America, the Great Basin and central Mexico, and the Pacific coastal regions. this was not passed due to insufficient evidence, but with an expectation to revisit the status when further evidence becomes available. The subspecies of the western interior have the darkest upperparts but a narrower dark crown above the white cheeks, and eastern S. c. carolinensis has the palest back, but a broader dark crown above the cheeks. Similar species Only three other species of nuthatches inhabit North America, the red-breasted nuthatch (S. canadensis), the pygmy nuthatch (S. pygmaea) and the brown-headed nuthatch (S. pusilla); their distributions all overlap with those of the white-breasted nuthatch. They are, however, clearly distinct and much smaller, since they are the smallest nuthatches, measuring 10 centimeters long and weighing around 10 grams. The red-breasted nuthatch has reddish underparts and has a black stripe on the eye. The pygmy nuthatch and the brown-headed nuthatch have a brown crown with a white spot on the nape. File:Sitta carolinensis png.png|White-breasted nuthatch (S. carolinensis) File:Sitta canadensis svg.png|Red-breasted nuthatch (S. canadensis) File:Sitta pygmaea.svg|Pygmy nuthatch (S. pygmaea) File:Sitta pusilla.svg|Brown-headed nuthatch (S. pusilla) == Distribution and habitat ==

The breeding habitat of the white-breasted nuthatch is woodland across North America, from southern Canada to northern Florida and southern Mexico. In the eastern part of its range, its preferred habitat is old-growth open deciduous or mixed forest, including orchards, parks, suburban gardens and cemeteries; it is found mainly in the lowlands, although it breeds at elevation in Tennessee. In the west and Mexico, the white-breasted nuthatch is found in open montane pine-oak woodlands, and nesting occurs at up to elevation in Nevada, California and Mexico. The white-breasted nuthatch is the only North American nuthatch usually found in deciduous trees; red-breasted, pygmy and brown-headed nuthatches prefer pines or other conifers. Although suitable habitat is distributed continentally, it is discontinuous. The separate populations of this non-migratory species have diverged to form distinct regional subspecies. The white-breasted nuthatch, like most of its genus, is non-migratory, and the adults normally stay in their territory year-round. There may be more noticeable dispersal due to seed failure or high reproductive success in some years, and this species has occurred as a vagrant to Vancouver Island, Santa Cruz Island, and Bermuda. One bird landed on the RMS Queen Mary six hours' sailing east of New York City in October 1963. == Ecology and behavior ==

The white-breasted nuthatch often travels with small mixed flocks in winter. These flocks are led by titmice and chickadees, with nuthatches and downy woodpeckers as common attendant species. Participants in such flocks are thought to benefit in terms of foraging and predator avoidance. It is likely that the attendant species also access the information carried in the chickadees' calls and reduce their own level of vigilance accordingly. File:White-breasted nuthatch 3145.jpg|In flight File:White-breasted Nuthatch (Sitta carolinensis) in flight.jpg|In flight, from above File:NuthatchThreat122713.jpg|In a threatening position Breeding The white-breasted nuthatch is monogamous, and pairs form following a courtship in which the male bows to the female, spreading his tail and drooping his wings while swaying back and forth; he also feeds her morsels of food. The pair establish a territory of in woodland, and up to in semi-wooded habitats, and then remain together year-round until one partner dies or disappears. The nest cavity is usually a natural hole in a decaying tree, sometimes an old woodpecker nest. The white-breasted nuthatch is omnivorous, eating insects and seeds. It places large food items such as acorns or hickory nuts in crevices in tree trunks, and then hammers them open with its strong beak; surplus seeds are cached under loose bark or crevices of trees. This bird will occasionally feed on the ground, and readily visits feeding stations for nuts, suet and sunflower seeds, the last of which it often takes away to store. Predators and parasites Predators of adult nuthatches include owls and diurnal birds of prey (such as sharp-shinned and Cooper's hawks), and nestlings and eggs are eaten by woodpeckers, small squirrels, and climbing snakes such as the western rat snake. The white-breasted nuthatch responds to predators near the nest by flicking its wings while making hn-hn calls. When a bird leaves the nest hole, it wipes around the entrance with a piece of fur or vegetation; this makes it more difficult for a predator to find the nest using its sense of smell. The estimated average lifespan of the white-breasted nuthatch is two years, The white-breasted nuthatch can be a host for certain parasites such as the protists Leucocytozoon or Trypanosoma. The white-breasted nuthatch is the typical host of another protist species, Haemoproteus sittae. Trematodes, such as Collyriclum faba, have also been recorded in this species. The white-breasted nuthatch can also be the target of hematophagous flies of the family Hippoboscidae, such as Ornithoica confluenta and Ornithomya anchineuria or of certain mites, such as Knemidokoptes jamaicensis, which produces scabies. == Conservation status ==

The white-breasted nuthatch is a common species with a large range, estimated at . Its total population is estimated at 10 million individuals, and there is evidence of an overall population increase, so it is not believed to approach either the size criterion (fewer than 10,000 mature individuals) or the population decline criterion (declining more than 30% in ten years or three generations) of the IUCN Red List. For these reasons, the species is evaluated as least concern by the International Union for the Conservation of Nature. The white-breasted nuthatch is protected under the Migratory Bird Treaty Act of 1918, to which the three countries in which it occurs (Canada, Mexico, and the United States) are all signatories. == References ==