Grey-backed hawk (Leucopternis occidentalis)

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Grey-backed hawk perched in tree
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Grey-backed hawk fact file

Grey-backed hawk description

KingdomAnimalia
PhylumChordata
ClassAves
OrderFalconiformes
FamilyAccipitridae
GenusLeucopternis (1)

Like other birds of prey, the grey-backed hawk (Leucopternis occidentalis) is an efficient hunter, possessing a tooth-like ridge on its upper bill, which is used to break the spine of its prey (4). This species can be distinguished by a broad, blackish mantle, which contrasts with the bright white throat, breast and underparts. The head and nape are grey with white streaks, the legs are yellow, and the tail is white, except for a black horizontal band just above the tail tips (2).

The juvenile grey-backed hawk is similar to the adult, except that the mantle is lighter and streaked with brown. The grey-backed hawk produces a distinctive, husky scream, ‘shreeyr’, which is often made repeatedly during flight (2).

Spanish
Busardo Dorsigrís, Gavilán Dorsigris.
Size
Length: 45 - 48 cm (2)
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Grey-backed hawk biology

The grey-backed hawk has a varied diet, mainly feeding upon reptiles during the breeding season, but also taking rodents, small birds, amphibians, crabs, earthworms and large insects (2) (5). On average, the grey-backed hawk will tackle prey at least as long as its own body, though it has been observed, on occasion, to take prey almost twice its length (5).

Studies suggest that the grey-backed hawk breeds almost all year round, but most frequently during the rainy season, from January to June. A large nest of up to 79 centimetres in diameter is constructed in the upper canopy of tall trees, in which the female lays a single bluish-white egg. Following the 36-day incubation period, the chick remains in the nest for a further 72 days, by which time it is ready to leave (5).

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Grey-backed hawk range

The grey-backed hawk is found in scattered sites around western Ecuador and the northwest of Peru (2).

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Grey-backed hawk habitat

The grey-backed hawk is most commonly found in moist evergreen forest, but may also occupy dry deciduous forest. This species has a preference for the forest edge, and is generally found at elevations between 100 and 1,400 metres, although it has also been observed as high as 2,900 metres (2).

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Grey-backed hawk status

The grey-backed hawk is classified as Endangered (EN) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

IUCN Red List species status – Endangered

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Grey-backed hawk threats

The forests of western Ecuador are considered to be one of the world’s most threatened ecosystems, and as a result of logging and clearance for agriculture, over 90 percent is now deforested. The impact of this habitat destruction on grey-backed hawk populations has undoubtedly been severe. As western Ecuador becomes increasingly developed and road networks expand, the pressure on this species and its habitat will only increase. Even in the areas where the grey-backed hawk is protected, such as the Mache-Chindul Ecological Reserve, illegal logging and hunting are common (2), and other activities that are detrimental to the bird’s habitat, such as livestock grazing, have been allowed to continue (6).

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Grey-backed hawk conservation

Although enforcement is severely lacking, populations of the grey-backed hawk residing within conservation areas, such as Machalilla National Park and Mache-Chindul Ecological Reserve in Ecuador, and Tumbes Reserved Zone (a part of the Northwest Peru Biosphere Reserve) in Peru, do at least receive a modicum of protection (2).

Nevertheless, in order to ensure the survival of this species, protection of existing sites must be consolidated, and further surveys of the bird’s population, as well as mapping of its distribution, should be undertaken so that new protected sites can be established (2).

View information on this species at the UNEP World Conservation Monitoring Centre.
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Find out more

Find out more about the grey-backed hawk and its conservation:

More information about biodiversity and conservation in western Ecuador:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Amphibians
Cold-blooded vertebrates of the class Amphibia, such as frogs or salamanders, which characteristically hatch as aquatic larvae with gills. The larvae then transform into adults with air-breathing lungs.
Deciduous forest
Forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.
Evergreen forest
Forest consisting mainly of evergreen trees, which retain leaves all year round. This is in contrast to deciduous trees, which completely lose their leaves for part of the year.
Incubation
The act of incubating eggs; that is, keeping them warm so that development is possible.
Mantle
In birds, the wings, shoulder feathers and back, when coloured differently from the rest of the body.
Nape
The back of the neck.
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References

  1. IUCN Red List (October, 2008)
    http://www.iucnredlist.org/
  2. BirdLife International (October, 2008)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=3485
  3. CITES (October, 2008)
    http://www.cites.org/
  4. Burnie, D. (2001) Animal. Dorling Kindersley, London.
  5. Vargas, H. (1995) Food Habits, Breeding Biology, and Status of the Gray-backed Hawk (Leucopternis occidentalis) in Western Ecuador. M.Sc. Thesis, Boise State University, Idaho.
  6. World Database on Protected Areas (October, 2008)
    http://www.wdpa.org/
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Image credit

Grey-backed hawk perched in tree  
Grey-backed hawk perched in tree

© Peter Horrell / peterhorrell.com

Peter Horrell
22 Rothesay Avenue
Chelmsford
Essex
CM2 9BU
United Kingdom
Tel: +44 (0) 7802 676308
peter@peterhorrell.com
http://www.peterhorrell.com

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