Fr: Buse cul-blanc
Ang: White-rumped hawk
All: Weißbürzelbussard
Esp: Busardo Culiblanco - Gavilán Negro - Aguilucho de Lomo Blanco
Ita: Poiana groppabianca
Nd: Witstuitbuizerd
Sd: vitgumpsvråk
Photographer:
Roger Ahlman
Pbase Galleries Peru and Ecuador
Text by Nicole Bouglouan
Sources:
HANDBOOK OF THE BIRDS OF THE WORLD Vol 2 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334156
A GUIDE TO THE BIRDS OF COLOMBIA by Steven L. Hilty and William L. Brown - Princeton University Press – ISBN 069108372X
BIRDS OF PERU by Thomas S. Schulenberg, Douglas F. Stotz, Daniel F. Lane, John P. O’Neill, Theodore A. Parker III – Princeton University Press 2007–ISBN: 978-0-691-13023-1
ORNITOLOGIA NEOTROPICAL - The Neotropical Ornithological Society
The White-rumped Hawk (Buteo leucorrhous) in Southern Brazil: status, conservation, and first description of the nest
By Felipe Zilio & André de Mendonça-Lima
Global Raptor Information Network - Working to Conserve Birds of Prey in nature
Neotropical Birds – Cornell Lab of Ornithology
White-rumped Hawk
Parabuteo leucorrhous
Accipitriformes Order – Accipitridae Family
INTRODUCTION:
The White-rumped Hawk is a very small, dark raptor. The white rump that gives the bird its name is usually conspicuous in flight.
It was formerly included in the genus Buteo, but it is now classified in the genus Parabuteo, alongside the Harris’s Hawk. Both species inhabit the New World.
The White-rumped Hawk is found in South America where it frequents subtropical and tropical montane forests.
This species is threatened by destruction of this forested habitat. However, this raptor is able to adapt and tolerate disturbed forest. Some declines are the result of the deforestation, but currently, the White-rumped Hawk is not globally threatened.
DESCRIPTION OF THE BIRD:
Biometrics:
Length: 33-40 cm
Wingspan: 67-79 cm
Weight: M: 290 g – F: 390 g
The White-rumped Hawk adult is mainly black overall, with conspicuous white rump and undertail-coverts. On the underwing, the coverts are creamy-white and the flight-feathers are barred black and whitish. The undertail is boldly barred black and white. On the uppertail, we can see only a narrower buffy-white bar and a very narrow white terminal band. The rufous thighs are slightly barred brown.
The hooked bill is dark grey with yellow cere. The eyes are yellow. Legs and feet are yellow too with black claws.
Male and female have similar plumage, but the female is larger than male. There is no clear evidence of the existence of a pale morph.
The juvenile/immature is dark brown mottled rufous above. Head, neck and underparts are creamy-buff with heavy dark brown streaking. Upper and undertail coverts are white. The tail is barred like in adults. The underwing shows more extended white than in adults. The eyes are duller, mostly paler yellow.
RANGE:
The White-rumped Hawk has Neotropical range. It can be found in W Colombia and Venezuela, S through Ecuador and Peru, to NW Bolivia.
There is another population in S Brazil (N to Minas Gerais), Paraguay, W Uruguay and N Argentina.
HABITAT:
The White-rumped Hawk occurs mainly in lower montane areas to middle elevations, 1700-2900 m in Colombia, 2000-3200 m in Ecuador, 1500-2500 m in Peru, 1400-3000 m in Venezuela and up to 3500 m in Bolivia.
It usually frequents moist forests and forest edges, and often occurs near clearings and broken forest on hillsides.
CALLS AND SONGS: SOUNDS BY XENO-CANTO
The White-rumped Hawk gives a short, whistled scream, dropping in pitch at the end “KEEEEiu”. This call is sometimes repeated tirelessly from a perch while wagging the tail.
It also produces a longer, high-pitched whistle ending sometimes in a quavering.
BEHAVIOUR IN THE WILD:
The White-rumped Hawk is known to hunt for rodents, reptiles, amphibians and insects. There are very few observations of active foraging. But as this raptor is often seen perched on exposed branches in tree canopy or subcanopy, we can suggest that this hawk hunts from perches, but also by soaring low over the ground.
Information about courtship displays is lacking, but some observations give us some details about this behaviour.
The White-rumped Hawk performs aerial displays in April-June. In Brazil, both mates were observed circling together while calling, performing dives and swooping flights, typical of numerous raptors.
However, a copulation observed in Ecuador in early June involved mostly perched vocalizations. The displays observed in Brazil probably occurred outside the breeding season, and were probably used to maintain and strengthen the pair-bonds. In Brazil, this species is presumed to breed in October, and most of these displays were recorded during the austral autumn, between April and June.
The White-rumped Hawk often occurs single and less frequently in pairs, soaring over the forest, especially in the morning. It often perches on trees and on exposed branches.
This species is probably mainly sedentary, although some wandering is recorded.
When the bird is flying, the black-and-white plumage pattern of both underwings and undertail is conspicuous. It is often seen displaying its white rump during the low soaring flights.
REPRODUCTION OF THIS SPECIES:
From an observation of a nest found in the Atlantic Forest of Brazil in 2012, some details are now available.
One nest was active in February/March in Colombia, whereas a copulation was observed in Ecuador in early June. On the other hand, an adult feeding a juvenile was observed in early January.
From the observation of the nest in S Brazil, the cup-shaped structure was found in a stand of pines (Pinus elliottii). It was placed in a fork of three branches, about 22 metres above the ground in pine tree. The nest was typically made with small Pinus branches and a few sticks of other plants. The cup was sparsely lined with green leaves.
Two creamy-white eggs with rusty-brown markings were inside the cup, each egg weighing 25-28 grams. The incubation of the Neotropical hawks lasts usually a month. The breeding period is closely related to weather and food availability.
PROTECTION / THREATS / STATUS:
The White-rumped Hawk appears to be rare or uncommon throughout its wide range. Some declines are the result of deforestation in NE Argentina. Elsewhere in the range, the species tolerates disturbed forests.
The population has not been quantified, but the White-rumped Hawk is currently evaluated as Least Concern. However, the status of this species is unclear and more information is required.
