White-rumped Hawk Parabuteo leucorrhous Scientific name definitions

The White-rumped Hawk is a very small raptor of humid montane forest with two apparently disjunct populations: it is found in the Andes from Venezuela to south to Bolivia, and also in the forested regions of Paraguay, southwestern Brazil, Uruguay and northern Argentina. In the Andes it is most often seen in soaring flight low over the canopy of fairly broken forest . There are very few observations of active foraging and so there is very little information on its diet, though it is known to take reptiles, frogs, insects and rats. As indicated by its common name, the most distinguishing characteristic of the White-rumped Hawk is its obvious white rump and under tail coverts, which contrast strongly with its all black chest, head, wings and back. When seen from below, the white-checkered underwing coverts and fairly long banded tail are conspicuous.

33–40 cm (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); male 290 g (n = 1), female 389 g (n = 1) (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ); wingspan 67–79 cm (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ). Small buteonine; deep blackish overall, with conspicuous white rump and undertail coverts and creamy white underwing coverts; thighs rufous; tail, from above has single narrow greyish-brown band in distal half, from below 2–3 white bands. Existence of pale morph, similar to that of B. brachyurus, has been claimed, but no clear evidence. Irides , cere, legs and feet yellow. Female similar to male, but slightly larger. Immature brown above, mottled with rufous; below heavily mottled rufous.

Previously placed in genus Buteo. In order to avoid apparent paraphyly, recent genetic study proposed resurrection of genus Percnohierax for this species (2 Riesing, M. J., L. Kruckenhauser, A. Gamauf, and E. Haring (2003). Molecular phylogeny of the genus Buteo (Aves: Accipitridae) based on mitochondrial marker sequences. Molecular Phylogenetics and Evolution 27(2):328–342. Close ), but such treatment shown to be unnecessary (3 Amaral, F.S.R., Sheldon, F.H., Gamauf, A., Haring, E., Riesing, M., Silveira, L.F. and Wajntal, A. (2009). Patterns and processes of diversification in a widespread and ecologically diverse avian group, the buteonine hawks (Aves, Accipitridae). Molecular Phylogenetics and Evolution. 53(3): 703–715. Close ). Monotypic.

Mountains of Venezuela and Colombia through Ecuador and Peru to Bolivia (La Paz, Cochabamba, Chuquisaca (4 Tobias, J.A. and Seddon, N. (2007). Ornithological notes from southern Bolivia. Bulletin of the British Ornithologists' Club 127(4): 293–300. Close ) ); Paraguay, S Brazil (but recorded N to Bahia) and N Argentina (Salta, Tucumán, Chaco and Misiones).

Dense higher-elevation forest, forest edge and Chaco; tropical to subtropical zones, occasionally to temperate; in subtropical zone, prefers dense forest. Occurs mostly at 1500–2900 m in Colombia, 1650–2500 m in Peru, and up to 3500 m in Bolivia; at lower elevations in Argentina (Misiones) and Paraguay.

Thought to be mostly sedentary, but periodically wanders, suggesting species is somewhat nomadic (1 Ferguson-Lees, J., and D. A. Christie (2001). Raptors of the World. Christopher Helm, London, UK. Close ).

Very little information available; known to take reptiles, frogs, insects and rats. Adult fed fledged juvenile "three small mouse-sized mammals" in Ecuador (5 Greeney, H. F., and T. Nunnery (2006). Notes on the breeding of north-west Ecuadorian birds. Bulletin of the British Ornithologists’ Club 126(1):38–45. Close ).

Typically a high-pitched whistle, with some variations however. Either a short note with a faint but conspicuous two-step dropping in pitch at the very end KEEEEiu  . Also a longer, more monotonous high-pitched whistle  , which sometimes ends in a quavering.

One nest active Feb–Mar in Colombia; in Ecuador, copulation observed in early Jun (6 Freile, J.F. and Chaves, J.A. (2000). Field observations on copulation by White-rumped Hawk Buteo leucorrhous. Cotinga. 14: 12. Close ), and adult seen feeding juvenile in early Jan (5 Greeney, H. F., and T. Nunnery (2006). Notes on the breeding of north-west Ecuadorian birds. Bulletin of the British Ornithologists’ Club 126(1):38–45. Close ). Clutch 2–3 eggs (Argentina). A nest with 2 eggs found in early Oct in S Brazil was on top of a Pinus elliottii, 22 m above the ground; nest a low cup made of small pine branches and sticks of other plants, lined with a few green leaves, 54 cm long, 38 cm wide and 18 cm deep; eggs creamy-white with rust-brown scrawls and spots, 42·6 mm × 34·7 mm and 44·5 mm × 34·5 mm (7 Zilio, F. and de Mendonça-Lima, A. (2012). The White-rumped Hawk (Buteo leucorrhous) in southern Brazil: status, conservation, and first description of the nest. Ornitología Neotropical. 23: 51–61. Close ). No further information available.

Not globally threatened (Least Concern). CITES II. Very little known, and status uncertain; generally rather local and nowhere common, but tolerates somewhat disturbed forest, so probably not threatened. No quantitative estimates have been made of global population size or population trends. In Argentina, seems to have decreased in response to deforestation; no recent records in NE Argentina. More data needed.