Bicolored hawk

The bicolored hawk was formally described in 1817 by the French ornithologist Louis Vieillot under the binomial name Sparvius bicolor. He specified Cayenne in French Guiana as the type locality. The bicolored hawk was formerly placed in the large and diverse genus Accipiter. In 2024 a comprehensive molecular phylogenetic study of the Accipitridae confirmed earlier work that had shown that the genus was polyphyletic. To resolve the non-monophyly, Accipiter was divided into six genera. The genus Astur was resurrected to accommodate 9 species, including the bicolored hawk, that had previously been placed in Accipiter. The resurrected genus had been introduced in 1799 by the French naturalist Bernard Germain de Lacépède. The genus name is from Latin astur, asturis meaning "hawk". The bicolored hawk is also closely related to the Cooper's hawk (A. cooperii) and Gundlach's hawk (A. gundlachi); these three form a superspecies. Until recently, the Chilean hawk (A. chilensis) from the colder, southernmost South America was treated as a race of A. bicolor but due to its differences in habitat preferences and plumages from the bicolored hawk, A. chilensis is now considered a full species. Four subspecies are recognised: • A. b. fidens (Bangs & Noble, 1918) – occurs in Eastern and Southern Mexico. ==Description==

At in length and in weight, it is significantly smaller than the northern goshawk of Eurasia and North America, and somewhat smaller than the Cooper's hawk of North America, but it is among the largest hawks in Central and South America (only the rare grey-bellied hawk is larger). As in other hawks, the female is far larger than the male. Adults are grey above with darker wings and crown, and a banded tail. The underparts typically vary from dark grey to very pale grey, but the southern subspecies can sometimes be rufescent below. The thighs are always pure rufous (not always easily seen), and the underwing coverts are white in the northern subspecies and rufous in the southern. Juveniles are very variable. They can be white, buff or rufous below, and sometimes with dark streaks. Their upperparts are browner than in adults, and the thighs are sometimes paler. ==Distribution and habitat==

The bicolored hawk is widespread but uncommonly observed. Its range extends from Mexico to west Ecuador, the Guianas to Colombia, south to east Peru, through Amazonian Brazil to Paraguay, north-northwestern Argentina, north of Uruguay, Bolivia and to Chile. It mainly resides in forest, along forest edges and in clearings in tropical and locally subtropical zones, ==Behaviour==

The bicolored hawk is difficult to detect due to its shyness and inconspicuousness. Because of this behaviour, the bicolored hawk may be more common than it seems. Vocalisations Its vocalisations are mainly subdued and unnoticeable. Males have been heard to give a soft, clear whistle and females can emit a loud "cac cac cac" when around the nest and young. During incubation, males give a sharp "kek" vocalisation upon arrival to the nest with food, to which the female replies with a nasal "wreh". Food and feeding These hawks capture prey in a stealthy manner by flying through dense vegetation to ambush unsuspecting prey. They may also capture prey through aerial pursuit after inconspicuously sitting and watching their target. At times, the bicoloured hawk may hunt in pairs. Most commonly, it feeds on smaller birds such as thrushes, mockingbirds and small doves, but has also been known to consume small mammals, including bats, as well as reptiles and large insects. The eggs are brooded for about three weeks by the female while the male forages for food. Bicolored hawk chicks are categorized as semi-altricial; the eyes are open at hatching but the chicks are not immediately mobile and are fed by the parents. The young fledge around 30–36 days after hatching and the fledgling period spans nearly seven weeks, during which the young will return to the nest frequently for food until they become independent. ==References==