Data Zone
Justification of Red List category
This species has a small and declining population with declines driven by the loss and degradation of suitable forest habitat but also potentially localised persecution. The species is assessed as Vulnerable. The rate of forest loss within the range has slowed over the past decade but maintaining current protected forest area and extending protection to additional remaining forest within the range is required to reduce the risk of extinction.
Population justification
Based on transect counts in different forest types in northwest Peru, the population density was calculated at 0.65 individuals/km2 (Piana 2016). Within the range, a total of c.24,000 km2 are covered by forest (Global Forest Watch 2023, using Hansen et al. [2013] data and methods therein). To account for the species' patchy distribution (see eBird 2023) and for the fact that many forest patches are too small and remote to offer suitable habitat (see Global Forest Watch 2023), it is precautionarily assumed that only 25% of forested habitat are occupied at this density (i.e., 6,000 km2). The global population may consequently number 3,900 individuals, which equates to 2,600 mature individuals. To account for uncertainty it is assumed that up to a potential maximum of 75% of forests may be occupied, giving an upper bound of 11,700 individuals or 7,800 mature individuals. Given the patchy nature of records and the species' general scarcity throughout the range the best estimate is set at the lower occupancy threshold and the population is estimated at between 2,500-8,000 with a best single value of 2,600 mature individuals.
Trend justification
This species is inferred to be declining as a consequence of habitat destruction and fragmentation; moreover, it is locally persecuted due to attacks on poultry. Blandariz et al. (2023) conducted analysis of expert responses on species change in western Ecuador and gave the species the highest score for 'retraction', corresponding to statements reporting loss from formerly occupied sites. Up until the 1980s, deforestation in western Ecuador proceeded rapidly at a rate of 57% per decade (Dodson and Gentry 1991), so that now mostly small fragments remain (see Global Forest Watch 2023). Forest loss has however since slowed and tree cover was lost at a rate of 9% over the past three generations (22.6 years), but from 2017 onward this slowed further to a rate equivalent to 4% over three generations (Global Forest Watch 2023, using Hansen et al. [2013] data and methods disclosed therein). Even considering the species' dependence on deciduous forests, and accounting for additional impacts of habitat degradation and fragmentation as well as hunting, population declines are likely slow. They are here tentatively placed in the band 1-19% over the past three generations, and slowing to 1-9% over three generations from 2017 onward.
Pseudastur occidentalis is confined to west Ecuador and adjacent north-west Peru. The species appears to be patchily distributed within its range, though observer coverage has been low (eBird 2023).
The species inhabits deciduous and dry deciduous forests, evergreen and cloud forest (Piana 2016, Bierregaard et al. 2020). It is somewhat tolerant of degraded habitat and is also seen in secondary forest, small patches and at forest edge (J. Freile in litt. 2000, O. Jahn in litt. 2007, P. Mena Valenzuela in litt. 2007, Piana and Marsden 2012, Bierregaard et al. 2020). It feeds on lizards, snakes, crabs, rodents, small birds, earthworms, frogs and large insects (Vargas 1995). Breeding appears to take place year round (Vargas 1995).
There has been extensive habitat destruction and fragmentation throughout its range, with over 90% of west Ecuador now deforested; below 900 m, the rate of deforestation in west Ecuador in 1958-1988 was 57% per decade (Dodson and Gentry 1991). Clearance for timber and agriculture, and intense grazing pressure from goats and cattle in the forest understorey, have led to this considerable reduction of forest cover in west Ecuador (Parker and Carr 1992). Even protected areas are affected by illegal settling, logging and livestock-grazing. Habitat loss continues, albeit at a much slower rate, and most remaining lowland forests are in various stages of degradation (Global Forest Watch 2023). Human persecution and retaliatory killings due to attacks on poultry is an additional threat in south-western Ecuador (Vargas 1995).
Conservation Actions Underway
CITES Appendix II. It occurs in several protected areas across its range, including Machalilla National Park (Ecuador) and Cerros de Amotape National Park (Peru), as well as further state and private reserves. Reforestation programmes are carried out in several private reserves such as Buenaventura, Jorupe, Canandé and Lalo Loor in Ecuador (H. Vargas in litt. 2012). The species is listed as Endangered at the national level in both Peru (SERFOR 2018) and Ecuador (Freile et al. 2019).
Conservation Actions Proposed
Study the species' ecology, population structure and dispersal abilities. Quantify the impact of threats, particularly hunting, on the population size. Monitor the population trend.
Protect areas of suitable habitat within the range. Sustainably manage protected areas and their buffer zones. Continue and expand habitat restoration programmes. Raise awareness for the species and its habitat. Enforce laws and regulations against illegal logging, hunting and colonisation inside protected areas.
45-48 cm. Medium-sized, black-and-white hawk. Adult has blackish mantle and wings. Grey head and nape, streaked white. White tail with broad, black subterminal band. White underparts. Yellow legs. Juvenile browner above with dusky streaking on mantle. Voice: A loud husky scream shreeeyr often repeatedly, primarily in flight, most similar to White Hawk Pseudastur albicollis (Coopmans et al. 2004).
Text account compilers
Hermes, C., Martin, R.
Contributors
Arosemena, J., Benstead, P., Berg, K., Freile, J., Horstman, E., Isherwood, I., Jahn, O., Mena-Valenzuela, P., Piana, R., Schulenberg, T., Sharpe, C.J., Symes, A., Vargas, H. & Sánchez-Nivicela, M.
Recommended citation
BirdLife International (2024) Species factsheet: Grey-backed Hawk Pseudastur occidentalis. Downloaded from
https://datazone.birdlife.org/species/factsheet/grey-backed-hawk-pseudastur-occidentalis on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.