Hook-billed kite

Hook-billed Kite
Scientific classification
Kingdom Information
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Bilateria
Branch	Deuterostomia
Phylum Information
Phylum	Chordata
Sub-phylum	Vertebrata
Infraphylum	Gnathostomata
Class Information
Superclass	Tetrapoda
Class	Aves
Sub-class	Neornithes
Infra-class	Neoaves
Order Information
Order	Accipitriformes
Sub-order	Accipitres
Family Information
Superfamily	Accipitroidea
Family	Accipitridae
Sub-family	Perninae
Genus Information
Genus	Chondrohierax
Species Information
Species	C. uncinatus
Synonyms	Falco uncinatus
Population statistics
Population	200,000 (2016 est)
Conservation status	Least concern

The hook-billed kite (Chondrohierax uncinatus) is a bird of prey of the family Accipitridae, and found throughout much of the subtropical and tropical regions of North and South America.

Description

The hooked-billed kite is a medium-sized raptor, about 15 to 20 inches long,with a wingspan of 30.6 to 38.5 inches, and weigh 7.5 to 12.7 ounces. Females are larger than males. It is polymorphic, i.e., there are three color morphs, gray (a characteristic seen primarily on male birds), brown (generally seen on female birds), and black. The gray morph has a gray-slate back and a lighter gray-blue head; the blackish tail has a whitish extremity and a broad gray central band; the ventral region is entirely gray, of a lighter shade than that of the back, and covered by a series of white streaks and sometimes by other thinner dark gray or reddish stripes, but in some specimens it is almost uniform. The brown morphs have a gray-to-dark brown back with a dark gray or black vertex, gray and reddish cheeks, a reddish collar and two gray stripes on the dark brown tail; the dorsal region is entirely reddish, more or less lined with white-cream stripes. The rare dark morph is almost completely slate-black, except for one or, more rarely, two large white or gray-white bands on the tail, and white spots on the underside of the primary feathers.

The bill has an elongated, hooked tip, giving the bird its name, and enabling it to extract snails from the shells. Between the bill and the white eyes is a yellow bold stripe. Legs and feet are small, yellow-orange in color. Juvenile birds do not differ much from the brown morph adults, but have feathers with a reddish margin on the back and wings, three thin brown bands on the tail, and white-cream abdomen with variably spaced thin dark or reddish horizontal bands.

Subspecies

• Chondrohierax uncinatus mirus; Lesser Antilles: Grenada
• Chondrohierax uncinatus uncinatus; southern United States and western Mexico, south to Brazil and northern Argentina

A third subspecies, C. u. wilsonii of Cuba, along with C. u. mirus, was investigated to determine genetically how different both island birds were as compared to the nominate subspecies of the mainland. What was discovered was that wilsonii had a much greater genetic sequence divergence estimate (1.8–2.0%) when compared with the mainland subspecies than did mirus (0.1–0.3%). The results caused the researchers to grant full species status to the Cuban kite as Chondrohierax wilsonii. A fourth assumed subspecies, C. u. aquilonis of western Mexico, had little to support a separation from the nominate subspecies.

Range and habitat

The hook-billed kite has a primarily neotropical range, but it has been observed as far north as the southern United States in Texas, and from northwestern Mexico (Sinaloa, Tamaulipas) to the south, through the plains of Central America, to South America. To the west of the Andes it goes as far as north-western Peru, while to the east of the Cordillera the species is present throughout the Amazon, up to central Peru, southern Bolivia, southern Brazil and northern Argentina. A particular subspecies, C. u. mirus, is endemic to Grenada, an island of the Lesser Antilles.

It is present in lowland areas, less commonly at medium altitudes, it is found in a wide range of forest habitats, including marshy forests, mangrove swamps, gallery forests, palm forests, evergreen mountain forests, coffee plantations and secondary forests, and in semi-open areas near water courses. In northern Mexico and adjacent areas of Texas, it is present in the arid thorny scrubland of acacia and in tropical deciduous forests.

Diet

It feeds almost entirely on snails, but occasionally it will also prey on frogs, salamanders, lizards, birds, large insects (including caterpillars) and spiders. It is a perch hunter, descending to the to capture terrestrial snails or other prey; it can also hunt in flight, remaining suspended in mid-air prior to swooping down. The researchers found that the size of the beak varies from one part of the range to the other, in correlation to the size of the most frequent arboreal snails in the region. Nevertheless, the beak of this kite is not as specialized as that of the everglade kite (Rostrhamus sociabilis) to extract the snails from its shell. Probably only rarely does it feed on the adult specimens of the large aquatic snails (for example the Ampullaridae), preferred prey of the everglade kite, but sometimes it consumes the younger specimens, which it may find on tree trunks.

Breeding

The hook-billed kite nests later than any other species of kite, probably to adapt to the seasonal changes in the abundance of prey, and the eggs hatch at the beginning of the rainy season, when the snails are more abundant. The nest is a very fragile cup-shaped platform, without padding and made up of small twigs, positioned at the bifurcation of a tree or on a horizontal branch, and so crude that from looking at it from below one can often see the eggs and chicks inside. Each brood consists of 1 to 3 eggs, off-white in color with chocolate brown spots. Incubation lasts for 34-35 days in Guatemala and for 38 or 39 days in Argentina. Both parents collaborate in nest building, incubation and chick feeding. In one nest observed in Suriname one of the two chicks was much larger than the other, which did not survive, suggesting the possibility of cainism in the species.

Threats

Overall, this species is classified by the ICUN as "least concern", due to the extensive range and large population. However, the subspecies C. u. mirus - endemic only to Grenada in the Caribbean - has been persecuted as a pest due to confusion with the broad-winged hawk (Buteo platypterus) in addition to habitat loss, and subsequently listed as "endangered".