Grey-backed hawk
{{Short description|Species of bird}}
{{Use American English|date=December 2022}}
{{Speciesbox
| image = Gray-backed Hawk - South-Ecuador S4E8637 (15478568822).jpg
| status = EN
| status_system = IUCN3.1
| genus = Pseudastur
| species = occidentalis
| authority = (Salvin, 1876)
| synonyms = Leucopternis occidentalis
| range_map = Pseudastur occidentalis map.svg
}}
The grey-backed hawk (Pseudastur occidentalis) is an Endangered species of bird of prey in subfamily Accipitrinae, the "true" hawks, of family Accipitridae. It is found in Ecuador and far northern Peru.{{cite web |url=https://www.worldbirdnames.org/bow/raptors/ |title=Hoatzin, New World vultures, Secretarybird, raptors |website=IOC World Bird List |version =v 12.2 |editor-last1=Gill |editor-first1= F. |editor-last2=Donsker|editor-first2=D.|editor-last3=Rasmussen |editor-first3=P. |date=August 2022 |access-date=December 8, 2022 }}Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 July 2022. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved July 24, 2022
Taxonomy and systematics
The grey-backed hawk was traditionally placed in genus Leucopternis but following a 2006 paper, taxonomists moved it and two other species to genus Pseudastur.Amaral, F.S.R., Miller, M.J., Silveira, L.F., Bermingham, E. and Wajntal, A. (2006). Polyphyly of the hawk genera Leucopternis and Buteogallus (Aves, Accipitridae): multiple habitat shifts during the Neotropical buteonine diversification. BMC Evolutionary Biology. 6(10): 1–21.Clements, J. F., T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, S. M. Billerman, B. L. Sullivan, and C. L. Wood. 2022. The eBird/Clements checklist of birds of the world: v2022. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/ retrieved November 10, 2022HBW and BirdLife International (2022) Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 6b. Available at: http://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6b_Jul22.zip retrieved December 5, 2022 The grey-backed hawk is monotypic.
Description
The grey-backed hawk is {{convert|45|to|52|cm|in|sigfig=2|abbr=on}} long with a {{convert|104|to|116|cm|in|sigfig=2|abbr=on}} wingspan. One female weighed {{convert|660|g|oz|sigfig=2|abbr=on}}. Females are about 10% larger than males and both sexes have the same plumage. Adults have a gray and white streaked head, nape, and mantle. They have blackish gray upperparts and a mostly white tail with a wide black band near the end. Their eye is dark brown, their cere gray, and their legs and feet pale yellow. Immatures have brownish gray upperparts, a dusky-striped nape, and gray spots on the breast.Bierregaard, R. O., G. M. Kirwan, D. A. Christie, and P. F. D. Boesman (2020). Gray-backed Hawk (Pseudastur occidentalis), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.gybhaw2.01 retrieved December 10, 2022
Distribution and habitat
The grey-backed hawk is found locally in western Ecuador between southern Esmeraldas and Loja provinces and slightly into Peru's Department of Tumbes. It inhabits subtropical and tropical semi-deciduous and evergreen forest, cloudforest, and secondary forest. It prefers moist areas and is often found in steep ravines. In elevation it mostly ranges between {{convert|100|and|1400|m|ft|sigfig=2|abbr=on}} but occurs as high as {{convert|2900|m|ft|abbr=on}}.
Behavior
=Movement=
=Feeding=
=Breeding=
The grey-backed hawk appears to nest at any time of the year but its breeding activity appears to be concentrated between December and April, the local rainy season. Pairs make display flights. Nothing else is known about its breeding biology.
{{birdsong|url=https://xeno-canto.org/species/Pseudastur-occidentalis |species=grey-backed hawk}}
=Vocalization=
Status
The IUCN originally assessed the grey-backed hawk as Threatened but since 1994 has classed it as Endangered. It has a small range and its estimated population of 250 to 1000 mature individuals is believed to be decreasing. The population is fragmented. Its forest habitat is undergoing continuing destruction for timber and agriculture. Even some nominally protected areas are illegally logged and cleared. The "combination of clearance for agriculture and timber supplies and intense grazing (by goats and cattle) in understorey has made [the western] Ecuadorian forests one of [the] world’s most threatened ecosystems."
References
{{Commons category|Pseudastur occidentalis}}
{{Wikispecies|Pseudastur occidentalis}}
{{Reflist}}
{{Taxonbar|from=Q1262047}}