Mirla Negra/Yellow-legged Thrush/Turdus flavipes

Nombre en español: Mirla Negra

Nombre en ingles: Yellow-legged Thrush

Nombre científico: Turdus flavipes

Familia: Turdidae

Canto: Peter Boesman

El zorzal azulado (Turdus flavipes) es una especie de ave paseriforme de la familia Turdidae propia del noreste de Sudamérica. Recientemente se lo ha vuelto a clasificar en el género Turdus, tras clasificarse en Platycichla.

Descripción

Este túrdido mide entre veintidós y veintitrés centímetros de largo y pesa entre cincuenta y cinco y setenta gramos. Ambos sexos tienen patas y ojos amarillos. El macho tiene pico amarillo y su plumaje es usualmente negro, con espalda y partes bajas de coloración grisácea. Sin embargo, el tono exacto de gris varía según la zona, y el macho de una de las cinco subespecies, P. f. xanthoscelus de Tobago, es completamente negro y se parece al mirlo macho. Las hembras tienen el pico opaco, partes bajas marrones oscuras y parte superior más pálida. Los pichones machos son de color castaño con alas y cola negra, mientras que las hembras se parecen a las adultas, pero con plumaje más opaco y salpicado de color naranja en la cabeza y ocre oscuro más cerca de las patas.

El canto del macho son frases musicales, srip, sriii, sri, sriii, nuevamente parecidos a los del mirlo, pero a veces imitan el canto de otros pájaros. La llamada típica es un srip con un peculiar siiit para indicar alarma.

Distribución y hábitat

Esta ave tiene un rango muy amplio. Una población habita el norte de Colombia, Venezuela, norte de Brasil, Trinidad y Tobago y parte de la Sierra de Pacaraima al oeste de Guyana (incluyendo el Monte Roraima). Otra población vive en el este de Brasil, este de Paraguay y noreste de Argentina. La subpoblación argentina es parcialmente migratoria: es residente en el norte, pero las que habitan más al sur pasan el invierno austral más al norte. Algunas poblaciones del norte de Sudamérica también forman parte de las grandes migraciones locales, pero sus casos no han sido completamente estudiados.

El hábitat de este pequeño túrdido es el bosque tropical, el renoval y las plantaciones muy crecidas. Es una especie de zonas altas, ya que suele anidar a más de dos mil metros sobre el nivel del mar, aunque se han encontrado individuos viviendo al nivel del mar. Se alimenta en árboles y arbustos, y muy raramente sobre la tierra, y su dieta consiste mayormente en frutas y frutos rojos. No forma bandadas muy grandes con otras especies ya que suele permanecer en las copas de los árboles.

El nido está formado por ramas pequeñas, tiene forma de cuenco y lo construyen entre rocas o sobre superficies sólidas. La hembra deposita entre dos y tres huevos de color rojizo, manchados de verde o azul cada ocasión.

Es muy común en gran parte de su rango, y por lo tanto el IUCN no la considera en peligro de extinción. Sin embargo, el zorzal azulado es una especie tímida, y la hembra en particular es muy difícil de ver, ya que no canta y su plumaje le permite camuflarse con su entorno.

Yellow-legged thrush

The yellow-legged thrush (Turdus flavipes) is a songbird of northern and eastern South America. In recent times, it is increasingly often placed in the genus Turdus again, however some taxonomists place this species in the genus Platycichla based on morphology. The South American Classification Committee of the American Ornithologists’ Union places it in the genus Turdus, as does the International Ornithological Committee.

Description

This thrush is 22–23 cm (8.7–9.1 in) long and weighs 55–70 g (1.9–2.5 oz). Both sexes have yellow legs and eye-ring. The male has a yellow bill and its plumage is usually black with a slate-grey back and lower underparts. However, the hue of the grey areas varies, and the male of one of the five subspecies, P. f. xanthoscelus of Tobago, is all-black, resembling the male Eurasian blackbird (Turdus merula). Females have a dull bill, warm brown upperparts and paler underparts. The juvenile male is brownish with black wings and tail, while the juvenile female resemble the adult female, but is duller, flecked with orange above and spotted and barred with dark brown below.

The song of the male is musical phrases, sreep, sreee, sree, sreee, again somewhat resembling that of the Eurasian blackbird, but sometimes including some imitation of other birds songs. The typical call is a sharp srip and a peculiar seeet given in alarm.

Distribution and ecology

It has a highly disjunct distribution. One population breeds in northern Colombia, Venezuela, far northern Brazil, Trinidad, and Tobago, as well as parts of the Pakaraima Mountains in western Guyana (including as it seems Mount Roraima). A second population occurs in eastern Brazil, eastern Paraguay, and far northeastern Argentina. The Argentine subpopulation is partially migratory, being resident in the northern part, while southernmost breeders spend the Austral winter further north. Some populations in northern South America also take part in local movements, but these are not well understood.

The habitat of this small thrush is rainforest, secondary woodland, and overgrown plantations. It is mainly a species of highlands up to 2,000 m (6,600 ft) ASL, but locally it occurs down to near sea level. The yellow-legged thrush mainly feeds in trees and bushes, infrequently on the ground, and mostly eats fruits and berries, e.g., Melastomataceae. It rarely if ever attends mixed-species feeding flocks, as its habit of keeping to the tree-tops makes it rarely worthwhile to join such conspicuous groups.

The nest is a lined shallow cup of twigs on a bank or amongst rocks. Two or three reddish-blotched green or blue eggs are laid.

It is fairly common in most of its range, and therefore listed as Least Concern by the IUCN. However, the yellow-legged thrush is a shy species, and the female in particular is difficult to see, since she does not sing and has a cryptic coloration.

With its curiously disjunct range, in northernmost South America, the islands of Trinidad and Tobago, parts of the Guiana Shield, and most extensively through the Atlantic Forest region, it is unsurprising that five subspecies of Yellow-legged Thrush have been named. These vary principally in overall body color, sometimes more obviously in females. In general, males are black to slate-gray with yellow legs, bill, and narrow eye-ring, while females are generally brown, becoming paler over the underparts, sometimes with a whitish chin, and also has yellow legs and a yellowish eye-ring. The Yellow-legged Thrush is generally fairly common and favors humid forest and secondary woodland, including adjacent clearings and plantations, to at least 2000 m. The species’ diet is principally fruit, and the nest is a shallow cup, typical of many thrushes, bound with mud; clutch size is two eggs. There is some suggestion of migratory movements in the north of the species’ range, and more clearly in the Atlantic Forest.