From Opus

Buteo magnirostris

Photo by Deca
Locality: Gonçalves, Minas Gerais, Brazil

[edit] Identification

Total length 32-44 cm (12½-17½ in). Southern subspecies largest. Sexes alike, but female average larger than male. Overall plumage very variable depending on subspecies, but all with barring to underparts, a dark-banded tail, barred secondaries and primaries with a rufescent patch on the latter (often distinctive in flight), yellowish eyes and orange-yellow cere and legs. Very roughly, the races can be divided into four groups (but the actual variation is more clinal):

• Mexico and northern Central America: Upperparts and head brown to grey-brown. Tail barred black and grey. Chest brownish or greyish (often streaky) and remaining underparts barred rufescent and white.
• Southern Central America and northern South America: Upperparts pure grey or greyish tinged brown. Tail banded black and grey (black and whitish from below). Chest grey and remaining underparts barred white and grey to rufescent brown.
• Central and eastern South America: Resemble previous, but upperparts more grey-brown and chest and barring to remaining underparts rufescent brown.
• South-central South America: Resemble previous, but barring to tail often rufescent and head and upperparts dark brown (head may appear almost blackish from a distance).

Juveniles generally have browner upperparts (often appears faintly light-scaled), a more streaky chest (less uniform than in adults of most subspecies), a whitish eye-brow and a little/no rufescent patch in the primaries. Juveniles initially have brown eyes, but this rapidly change to yellow as in the adults.

Generally easily recognized by the yellow eyes, the rufesent patch in the primaries and the pattern to the underparts. Grey individuals from northern South America are commonly confused with various forest-falcons (notably the Barred, the Lined and the Plumbeous) or the Grey-lined Hawk.

Photo by gaviao-real
Locality: Ilha de Marajó, Brazil.

[edit] Distribution

Found from Mexico, south through most of Central America, to South America as far south as NW Peru on the Pacific slope and central Argentina east of the Andes. Absent from the higher parts of the Andes and most of the Pacific slope of Peru (where too dry; see habitat). There are a number of records from Texas, USA.

Typically common, and in most its range the single most commonly observed species of raptor (perhaps except for certain vultures and caracaras).

[edit] Taxonomy

[edit] Subspecies

Many subspecies of the Roadside Hawk have been described, some of which typically are considered invalid.

[edit] Rupornis vs. Buteo

Molecular evidence by Reising et al. (2003) presented evidence for Buteo being polyphyletic in its current treatment. According to the data, Buteo could retain its monophyly if the Roadside Hawk was placed in the monotypic genus Rupornis and the White-rumped Hawk was placed in the monotypic genus Percnohierax. Alternatively, if these two species stayed in Buteo, genera Parabuteo and Geranoaetus would need to be placed in Buteo to avoid paraphyly. At present most authorities keep the Roadside Hawk in Buteo, and the Opus follows in this consensus.

[edit] Habitat

Virtually any habitat with some trees. Avoids the interior of dense humid forest and deserts, but more or less every habitat in between is utilized by this species. Occurs up to an altitude of 2500 m (8200 ft), but rare above 1500 m (4900 ft). Benefits from the widespread clearance of humid forest (e.g. the Amazon) within its range.

[edit] Behaviour

Most commonly seen singly, but occasionally in pairs or small (family?) groups. A true generalist, feeding mainly on insects, small mammals and reptiles, but has also been recorded feeding on small birds and fishes. Mainly hunts from a perch. Breeding is seasonal, but timing varies between regions. The typically 1-2 eggs are laid in a large stick-nest in a tree. Generally easily observed and not shy. The most commonly heard vocalization is a loud scream, typically given while perched (but also sometimes in flight). Flight consists of a series of rapid flaps alternated with short glides. Only infrequently soars.

[edit] External Links