Agateador Euroasiático

Identificación

Similar in appearance, all treecreepers are small birds with streaked and spotted brown upperparts, rufous rumps and whitish underparts. They have long decurved bills, and long rigid tail feathers that provide support as they creep up tree trunks looking for insects.<p>The Eurasian treecreeper is 12.5 cm (4.9 in) long and weighs 7.0–12.9 g (0.25–0.46 oz). It has warm brown upperparts intricately patterned with black, buff and white, and a plain brown tail. Its belly, flanks and vent area are tinged with buff. The sexes are similar, but the juvenile has duller upperparts than the adult, and its underparts are dull white with dark fine spotting on the flanks.<p>The contact call is a very quiet, thin and high-pitched sit, but the most distinctive call is a penetrating tsree, with a vibrato quality, sometimes repeated as a series of notes. The male's song begins with srrih, srrih followed in turn by a few twittering notes, a longer descending ripple, and a whistle that falls and then rises.<p>The range of the Eurasian treecreeper overlaps with that of several other treecreepers, which can present local identification problems. In Europe, the Eurasian treecreeper shares much of its range with the short-toed treecreeper. Compared to that species, it is whiter below, warmer and more spotted above, and has a whiter supercilium and slightly shorter bill. Visual identification, even in the hand, may be impossible for poorly marked birds. A singing treecreeper is usually identifiable, since short-toed treecreeper has a distinctive series of evenly spaced notes sounding quite different from the song of Eurasian treecreeper; however, both species have been known to sing the other's song.<p>Three Himalayan subspecies of Eurasian treecreeper are now sometimes given full species status as Hodgson's treecreeper, for example by BirdLife International, but if they are retained as subspecies of Eurasian, they have to be distinguished from three other South Asian treecreepers. The plain tail of Eurasian treecreeper differentiates it from bar-tailed treecreeper, which has a distinctive barred tail pattern, and its white throat is an obvious difference from brown-throated treecreeper. Rusty-flanked treecreeper is more difficult to separate from Eurasian, but has more contrasting cinnamon, rather than buff, flanks.<p>The North American brown creeper has never been recorded in Europe, but an autumn vagrant would be difficult to identify, since it would not be singing, and the American species' call is much like that of Eurasian treecreeper. In appearance, brown creeper is more like short-toed than Eurasian, but a vagrant might still not be possible to identify with certainty given the similarities between the three species.

Taxonomía

The Eurasian treecreeper was first described under its current scientific name by Linnaeus in his Systema naturae in 1758. The binomial name is derived from Ancient Greek kerthios, a small tree-dwelling bird described by Aristotle and others, and Latin familiaris, familiar or common.<p>This species is one of a group of very similar typical treecreeper species, all placed in the single genus Certhia. Eight species are currently recognised, in two evolutionary lineages: a Holarctic radiation, and a southern Asian group. The Holarctic group has a more warbling song, always (except in C. familiaris from China) starting or ending with a shrill sreeh. Species in the southern group, in contrast, have a faster-paced trill without the sreeh sound. All the species have distinctive vocalizations and some subspecies have been elevated to species on the basis of their calls.<p>The Eurasian treecreeper belongs to the northern group, along with the North American brown creeper, C. americana, the short-toed treecreeper, C. brachydactyla, of western Eurasia, and, if it is considered a separate species, Hodgson's treecreeper, C. hodgsoni, from the southern rim of the Himalayas.<p>The brown creeper has sometimes been considered to be a subspecies of Eurasian treecreeper, but has closer affinities to short-toed treecreeper, and is normally now treated as a full species. Hodgson's treecreeper is a more recent proposed split following studies of its cytochrome b mtDNA sequence and song structure that indicate that it may well be a distinct species from C. familiaris.<p>There are nine to twelve subspecies of Eurasian treecreeper, depending on the taxonomic view taken, which are all very similar and often interbreed in areas where their ranges overlap. There is a general cline in appearance from west to east across Eurasia, with subspecies becoming greyer above and whiter below, but this trend reverses east of the Amur River. The currently recognised subspecies are as follows:

Nombre científico

Certhia familiaris

Autoridad

Linnaeus, 1758

Orden

Passeriformes

Familia

Certhiidae

Género

Certhia

Distribución y hábitat

The Eurasian treecreeper is the most widespread member of its genus, breeding in temperate woodlands across the Palearctic from Ireland to Japan. It prefers mature trees, and in most of Europe, where it shares its range with short-toed treecreeper, it tends to be found mainly in coniferous forest, especially spruce and fir. However, where it is the only treecreeper, as in European Russia, or the British Isles, it frequents broadleaved or mixed woodland in preference to conifers. It is also found in parks and large gardens.<p>The Eurasian treecreeper breeds down to sea level in the north of its range, but tends to be a highland species further south. In the Pyrenees it breeds above 1,370 metres (4,490 feet), in China from 400–2,100 metres (1,300–6,900 ft) and in southern Japan from 1,065–2,135 metres (3,494–7,005 ft). The breeding areas have July isotherms between 14–16 °C and 23–24 °C (73–75 °F) and 72–73 °F).<p>The Eurasian treecreeper is non-migratory in the milder west and south of its breeding range, but some northern birds move south in winter, and individuals breeding on mountains may descend to a lower altitude in winter. Winter movements and post-breeding dispersal may lead to vagrancy outside the normal range. Wintering migrants of the Asian subspecies have been recorded in South Korea and China, and the nominate form has been recorded west of its breeding range as far as Orkney, Scotland. The Eurasian treecreeper has also occurred as a vagrant to the Channel Islands (where the short-toed is the resident species), Majorca and the Faroe Islands.

Migración

Especie residente

Comportamiento

Patrón migratorio: Especie residente.

Conservación

Tendencia poblacional: estable.

Tendencia poblacional

estable