the white-breasted nuthatch (sitta carolinensis) is a small songbird of the nuthatch family which breeds in old-growth woodland across much of temperate north america .
it is a stocky bird , with a large head , short tail , powerful bill and strong feet .
the upperparts are pale blue-gray , and the face and underparts are white .
it has a black cap and a chestnut lower belly .
the nine subspecies differ mainly in the color of the body plumage .
like other nuthatches , the white-breasted nuthatch forages for insects on trunks and branches , and is able to move head-first down trees .
seeds form a substantial part of its winter diet , as do acorns and hickory nuts that were stored by the bird in the fall .
the nest is in a hole in a tree , and the breeding pair may smear insects around the entrance as a deterrent to squirrels .
adults and young may be killed by hawks , owls and snakes , and forest clearance may lead to local habitat loss , but this is a common species with no major conservation concerns over most of its range .
the nuthatches are a genus , sitta , of small passerine birds which derive their  english name from the propensity of some species to wedge large insects or seeds into cracks , and then hack at them with their strong bills .
sitta is derived from sitt , the 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 .
nuthatch taxonomy is complex , with geographically separated species sometimes closely resembling each other .
the white-breasted nuthatch has a similar appearance and contact call to the white-cheeked nuthatch , sitta leucopsis , of the himalayas and was formerly considered to be conspecific .
like other members of its genus , the white-breasted nuthatch has a large head , short tail , short wings , a powerful bill and strong feet; it is 1314 cm (56 in) long , with a wingspan of 2027 cm (811 in) and a weight of 1830 g (0.641.06 oz) .
the adult male of the nominate subspecies , s .
c .
carolinensis , has pale blue-gray upperparts , a glossy black cap (crown 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 underparts are white .
the outer tail feathers are black with broad diagonal white bands across the outer three feathers , a feature readily visible in flight .
the female has , on average , a narrower black back band , slightly duller upperparts and buffer underparts than the male .
her cap may be gray , but many females have black caps , and cannot be reliably distinguished from the male in the field .
in the northeastern united states , at least 10% of females have black caps , but the proportion rises to 4080% in the rocky mountains , mexico and the southeastern u .
s .
juveniles are similar to the adult , but duller plumaged .
like other nuthatches , this is a noisy species with a range of vocalizations .
the male's mating song is a rapid nasal qui-qui-qui-qui-qui-qui-qui .
the contact call between members of a pair , given most frequently in the fall and winter is a thin squeaky nit , uttered up to 30 times a minute .
a more distinctive sound is a shrill kri repeated rapidly with mounting anxiety or excitement kri-kri-kri-kri-kri-kri-kri-kri; the rocky mountains and great basin subspecies have a higher , faster yididitititit call , and pacific birds a more nasal beeerf .
three other , significantly smaller , nuthatches have ranges which overlap that of white-breasted , but none has white plumage completely surrounding the eye .
further distinctions are that the red-breasted nuthatch has a black eye line and reddish underparts , and the brown-headed and pygmy nuthatches each have a brown cap , and a white patch on the nape of the neck .
the white-breasted nuthatch has nine subspecies , although the differences are small and change gradually across the range .
the subspecies are sometimes treated as three 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 .
the subspecies of the western interior have the darkest upperparts , and eastern s .
c .
carolinensis has the palest back .
the eastern form also has a thicker bill and broader dark cap stripe than the interior and pacific races .
the calls of the three groups differ , as described above .
the great basin and eastern forms have been observed in secondary contact on the great plains , where they do not seem to mix .
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 1,675 m (5,500 ft) altitude in tennessee .
in the west and mexico , this nuthatch is found in open montane pine-oak woodlands , and nesting occurs at up to 3,200 m (10,500 ft) altitude in nevada , california and mexico .
pinyon-juniper and riverside woodlands may be used locally where available .
the white-breasted nuthatch is the only north american nuthatch usually found in deciduous trees; red-breasted , pygmy and brown-headed nuthatches prefer pines .
the presence of mature or decaying trees with holes suitable for nesting is essential , and trees such as oak , beech and hickory are favored in the east since they provide edible seeds .
although suitable habitat is distributed continentally , it is discontinuous , and the separate populations of this non-migratory species have diverged to form distinct regional subspecies .
this 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 in october 1963.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 0.100.15 square kilometers (2538 acres) in woodland , and up to 0.2 square kilometers (50 acres) 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 , and occasionally an artificial nest box intended for the eastern bluebird .
the nest hole is usually 312 m (1040 ft) high in a tree and is lined with fur , fine grass , and shredded bark .
the clutch is five to nine eggs which are creamy-white , speckled with reddish brown , and average 19 x 14 mm (0.75 x 0.55 in) in size .
the eggs are incubated by the female for 13 to 14 days prior to hatching , and the altricial chicks fledge in a further 18 to 26 days .
both adults feed the chicks in the nest and for about two weeks after fledging , and the male also feeds the female while she is incubating .
once independent , juveniles leave the adults' territory and either establish their own territory or become "floaters", unpaired birds without territories .
it is probably these floaters which are mainly involved in the irregular dispersals of this species .
this species of nuthatch roosts in tree holes or behind loose bark when not breeding , and has the unusual habit of removing its faeces from the roost site in the morning .
it usually roosts alone except in very cold weather , when up to 29 birds have been recorded together .
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 smooth green 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 nuthatch may also smear blister beetles around the entrance to its nest , and it has been suggested that the unpleasant smell from the crushed insects deters squirrels , its chief competitor for natural tree cavities .
the estimated average lifespan of this nuthatch is two years , but the record is twelve years and nine months .
this nuthatch's responses to predators may be linked to a reproductive strategy .
a study compared the white-breasted nuthatch with the red-breasted nuthatch in terms of the willingness of males to feed incubating females on the nest when presented with models of predators .
the models were of a sharp-shinned hawk , which hunts adult nuthatches , and a house wren , 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 .
the white-breasted nuthatch forages along tree trunks and branches in a similar way to woodpeckers and treecreepers , but does not use its tail for additional support , instead progressing in jerky hops using its strong legs and feet .
all nuthatches are distinctive when seeking food because they are able to descend tree trunks head-first and can hang upside-down beneath twigs and branches .
this 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 .
the diet in winter may be nearly 70% seeds , but in summer it is mainly insects .
the insects consumed by the white-breasted nuthatch include caterpillars , ants , and pest species such as pine weevils , oystershell and other scale insects , and jumping plant lice .
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 .
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 .
the white-breasted nuthatch is a common species with a large range , estimated at 8.6 million square kilometers (3.3 million square miles) .
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 .
the removal of dead trees from forests may cause problems locally for this species because it requires cavity sites for nesting; declines have been noted in washington , florida , and more widely in the southeastern u .
s .
west to texas .
in contrast , the breeding range is expanding in alberta , and numbers are increasing in the northeast due to regrown forest .
this 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 .
