The Corsican nuthatch (Sitta whiteheadi ) 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 Corsican nuthatch is found only on the island of Corsica, where it populates the old forests of high altitude laricio pines, descending lower in winter. Its scientific name comes from John Whitehead, the ornithologist who brought the bird to the attention of the scientific community in 1883. The Corsican nuthatch is closely related to the Chinese nuthatch (S. villosa ) and the red-breasted nuthatch (S. canadensis ). It is threatened by loss of nesting sites and habitat fragmentation, with an estimated population size of about 2,000 individuals, possibly in moderate decline. Due to the small population size and the limited range, the conservation status of the Corsican nuthatch is classed as "vulnerable" by the International Union for Conservation of Nature.
The Corsican nuthatch is sometimes referred to as Whitehead's nuthatch, but it has a variety of local names in the Corsican language, such as pichjarina, pichja sorda or furmicula, and capinera, used at least in Corte.: 5–6 The species remains relatively unknown to the public. The regional natural park of Corsica has published a small comic strip on the bird, and the "Corsican ornithological group" (GOC) has chosen the species as its logo, represented in a very refined form. In the forest of Aïtone, near Évisa, the National Forestry Office has created a "nuthatch trail", which is one of the places where the species can be more easily observed.: 25–30
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Altricial animals are those species whose newly hatched or born young are relatively immobile. They lack hair or down, are not able to obtain food ...
A territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
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Partial MigrantPartial migration is when within a migratory species or even within a single population, some individuals migrate while others do not.
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The Corsican nuthatch is the only species of bird endemic to Corsica, and even to metropolitan France. Its range covers the majority of the island, which is very mountainous. This bird is found from the Tartagine-Melaja forest in the north to the Ospedale forest in the south, but it is particularly abundant in the Monte Cinto, Monte Rotondo, Monte Renoso and Monte Incudine massifs. There are also two isolated populations, in Castagniccia in the northeast of the island, and in the Cagna mountain in the south.
The Corsican nuthatch favors Corsican pines (Pinus nigra laricio) forests interspersed with clearings; this habitat is fairly dry in the summer (three weeks to two months of drought) and experiences heavy rainfall in the off-season (800–1,800 mm (31–71 in) per year).: 9–14 This nuthatch is sedentary; it generally lives in deep valleys between 1,000 m (39,000 in) and 1,500 m (59,000 in) above sea level between April and October, but can be found from 750–1,800 mm (30–71 in) above sea level, although the more open forests at higher elevations are less suitable. It descends lower in winter, and may then inhabit mixed forests of Corsican and maritime pines (Pinus pinaster) or forests of white fir (Abies alba) ; however, its stand indices are significantly lower than in pure Corsican pines forests.: 15–25 It avoids hardwood-dominated or mixed woodlands.: 9–14
Old pines provide the nuthatch with abundant food, and the species is absent from sectors where trees are less than 28 cm (11 in) in diameter, and where the Corsican pine is in the minority compared to other species. The places most likely to shelter the Corsican nuthatch have large trees (over 16 m (630 in) high) and large diameter (over 58 cm (23 in)). The preference of the bird for the Corsican pine over the maritime pine could be explained by the toughness of the seeds of the latter. From a historical perspective, Thibault and colleagues explain in 2002 that "the Corsican nuthatch and the Corsican pine, probably present on the island since at least the middle of the Quaternary, had to face the last climatic fluctuations of the Pleistocene, which caused deep modifications in the composition and distribution of the vegetation. It is likely that the nuthatch survived in the Corsican pines throughout this period.
Like all nuthatches, the Corsican nuthatch can move head down along branches, and is rarely found on the ground. It is a territorial bird and are not shy. It lives in monogamous couples evolving all year long on the same territory of three to ten hectares, the two birds of the couple defending it from intruders, of the same species or of another. The home range, the area where the birds generally live within their territory, varies in size, depending on the season and age of the birds, but especially on the cone production of the pines.: 15–25
The Corsican nuthatch consumes mainly pine nuts, but also small flying insects in summer. From March to November, small arthropods (adult insects and their larvae, spiders) represent the main part of its diet; it catches them in flight but more generally in the trees; it makes a quarter of its captures in flight, from a lookout post, and exploits the rest of the time the substrates provided by the trees. In spring and summer, it is more likely to be found in the treetops, foraging high up in the foliage of pine trees, at the end of branches, like a chickadee; in autumn, however, it searches for food along the trunks and on large branches, and may also form mixed feeding flocks with other small passerines outside the breeding season. November marks the beginning of the opening of pine cones, from which the Corsican nuthatch extracts seeds with its fine bill. In years of high production, the nuthatch may find food resources in the cones until March. As nuthatches often do, the Corsican nuthatch hides some seeds under the bark or under lichens or plant debris, and consumes them in the off-season, especially when early spring snows prevent access to pine cones, or when cones remain closed on wet, cold days. This use of hiding places may also partly explain the bird's complete sedentarity.
Male Corsican nuthatches begin singing in late December, but the breeding season occurs in April–May. In years of high cone production, breeding occurs early; in years of low production, nuthatches must wait until insects are present in large quantities. The species depends for its nesting on old conifers that are two to three hundred years old with sufficiently soft trunks, dead, worm-eaten or partially struck by lightning. The Corsican nuthatch favors dead trees that still have some branches, which can be used as a singing post, as a stalking post or to monitor the surroundings, but the height of the trunk, the surrounding pine cover or the diameter of the trunk are not decisive.: 15–25
A 2005 study reported that the nests of different pairs were located 284–404 m (932–1,325 ft) apart depending on the year (between 1998 and 2003). Both members of the pair excavate the nest, often reusing cavities excavated by great spotted woodpeckers (Dendrocopos major ), but avoiding the high risk of predation from the former nests of these birds. There can be two entrances to the cavity if the trunk is particularly rotten. The entrance is 3–4 m (120–160 in) wide, and the cavity averages 56 mm × 109 mm (2.2 in × 4.3 in) with an average depth of 12 cm (4.7 in). The nest is placed between 2–30 m (79–1,181 in) above the ground. It is made of various plant materials (pine thorns, bark, and shavings) and lined with softer materials such as feathers, moss, horsehair, or lichen.
The female lays in late April or early May, four to six (average 5.1) oval white eggs with reddish-brown spots, especially on the broad end, with "a few faint brown or dark gray-purple markings. Whitehead compares the eggs in size to those of the great tit (Parus major ); according to Jourdain, who compares 42 eggs (14 collected by Whitehead, the other 28 by himself), they measure on average 17.18 mm × 12.96 mm (0.68 in × 0.51 in). The average weight, calculated for 17 of these eggs, is 82.2 milligrams. Brooding lasts from 14 to 17 days; it is carried out by the female alone, which the male feeds on average 3.2 times per hour. The beak and wing of the chicks grow steadily, while the tarsus stabilizes by the twelfth day; the crown darkens by the eleventh day, and the young are fully plumaged after an average of twenty days.
The brood usually has 3 to 6 (average 4.3) fledglings, which leave the nest at 22 to 24 days of age. If the first brood fails or is lost, the pair makes a second brood between May 28 and June 16; one-third of these replacement broods are made in another tree. From one year to the next, nearly half of the pairs change trees to nest in. The young may breed at one year of age. The annual survival rate has been estimated at 61.6% for males (more than three out of five individuals make it through the year); life expectancy is poorly known, but "color marking has shown that a small number of individuals can reach six years of age".
The decrease in numbers can be explained by fire and logging: the Corsican pines to which the species is attached regenerate less quickly than they otherwise disappear, and the felling of dead pines poses problems for the nesting of this nuthatch. In addition to destroying the birds' territories, regrowth after the fire has passed results in the replacement of the laricio pine by maritime pine or holm oak (Quercus ilex ). A study carried out on the consequences of the fires of the summer of 2000, which affected several large Corsican massifs, concluded that the direct consequences (disappearance of territories) and indirect consequences (difficulties in nesting and feeding in winter) could have affected 4% of the species' population. For the same period in the Restonica gorges, 6 out of 12 territories were lost. The major impacts of the forest fires of August 2003 also led to a decline in the population, which was reduced by 37.5% the following spring.
Predators of the Corsican nuthatch include the great spotted woodpecker, which may attack nests and young birds by enlarging the nest cavity to gain access to nuthatch offspring; not all individuals necessarily attack nests, and nuthatches and woodpeckers may even nest in the same tree. The garden dormouse (Eliomys quercinus ) is also a potential predator, having been observed sleeping in a nest and suspected of several losses; to a lesser extent, the Eurasian sparrowhawk (Accipiter nisus ) could count the Corsican nuthatch among its prey: nuthatch remains were reported in the diet of one of these birds of prey in 1967, and Löhrl reported in 1988 that the Corsican nuthatches he raised in captivity would hide at the sight of a raptor. The Eurasian jay (Garrulus glandarius ) may also be a more or less important predator of fledglings.: 25–30
The study of the habitat structure of the Corsican nuthatch has shown that the fragmentation of its habitat, which leads to a local concentration of populations, could be a new threat. Nuthatches avoid open areas and young plantations that present an increased risk of predation, only crossing them if these areas are sufficiently narrow.: 34–42 A 2011 study attempted to quantify the impact of global warming on the future distribution of Corsican and maritime pines; taking only climate disruption into account, it is likely that by 2100, 98% of the Corsican nuthatch's range will still be likely to support it, and that this distribution will even expand by 10%. The bird's habitat is thus more threatened by the increase in frequency and importance of fires and the increase in human activities than by climate change.
The Corsican nuthatch is fully protected on French territory by virtue of article 3 of the decree of October 29, 2009, establishing the list of protected birds on the whole territory and the modalities of their protection; it is also listed in Annex I of the European Union Birds Directive and in Annex II of the Berne Convention. It is therefore forbidden to destroy, mutilate, capture or remove it, to intentionally disturb it or naturalize it, as well as to destroy or remove eggs and nests, and to destroy, alter or degrade its environment. Whether alive or dead, it is also prohibited to transport, peddle, use, hold, sell or buy it.
It is estimated that 9-11% of the individuals are located in eight of the Special Protection Areas of the Birds Directive. Less than another five percent of the estimated population is found in two managed biological reserves and six integral biological reserves. In addition to fire prevention and control, specific measures are envisaged for the protection of the species, mainly focused on forestry methods and strategies: the first priority is to be given to the structure of the habitat; the second priority is given to the presence of nesting sites.: 34–42
