Data Zone
Justification of Red List category
This species has a very small, patchily distributed population. The destruction of its montane forest habitat as well as direct human persecution are driving a moderately rapid population decline. The species is therefore listed as Endangered.
Population justification
The species is thought to be rare and patchily distributed (Thiollay 1994, Ferguson-Lees and Christie 2001).
The population in Venezuela is thought to number in the low hundreds or perhaps 200 mature individuals (C. J. Sharpe in litt. 2003, 2015). In Colombia, the population has been estimated at 320-640 mature individuals (Renjifo et al. 2014). The population in Ecuador has been placed in the band 50-249 mature individuals (Freile et al. 2019), while the population in Peru is thought to number not more than 330 mature individuals (SERFOR 2018). In Bolivia, the population numbers likely fewer than 250 mature individuals (S. K. Herzog in litt. 2013). The population in Argentina is placed in the band 250-2,499 mature individuals (MAyDS and AA 2017). Considering these national population estimates, the global population is here precautionarily placed in the band 1,400-4,200 mature individuals. The distribution range is highly disjunct; observational records (per eBird 2023) suggest that it forms at least ten very small subpopulations.
Trend justification
This species prefers dense primary forests (C. J. Sharpe in litt. 2003, T. Donegan in litt. 2010, Rivas-Fuenzalida et al. 2022), although it may persist in mosaics of primary and secondary forest with open areas (C. Márquez in litt. 2012). Throughout its range, tree cover has been lost at a rate equivalent to 7-9% over three generations (31.7 years), extrapolated from losses over 2000-2022 (Global Forest Watch 2023, using Hansen et al. [2013] data and methods disclosed therein). This value does however not account for the disturbance and degradation of habitat, which may exacerbate the overall rate of habitat loss. In addition to declines caused by forest loss, the species is suffering from high hunting and poaching pressure in many parts of its range; studies found direct mortality due to human-eagle conflict in over half of the territories investigated (Rivas-Fuenzalida et al. 2022, 2023). Due to the species' long generation length of 10.55 years and its slow reproduction, the killing of adults and poaching of nestlings is likely to have disproportionately high impacts on the population trend. Importantly, ongoing forest loss is increasing the risk of conflict and persecution (Restrepo-Cardona et al. 2019).
Based on ongoing forest loss throughout its range and reports of direct mortality, a continuing decline in the population size is inferred. Even though there is no direct quantification of the trend, the above information on the intensity of threats suggests that declines may approach 30% over three generations. Preliminarily therefore, they are here placed in the band 20-29% over three generations.
This species has an extensive, but narrow, disjunct and altitudinally restricted, linear distribution on the coastal ranges of north-central Venezuela (Carabobo and Aragua) and north-eastern Colombia (Santa Marta Mountains), and from the subtropical slopes of the Andes from Venezuela (Mérida and Perijá Mountains) through Colombia, Ecuador and Peru to west-central Bolivia and north-western Argentina.
This species is found on heavily forested mountain slopes, probably occurring mostly in large valleys; it is recorded up to 3,500 m, but is usually found at 1,500-2,800 m (Fjeldså and Krabbe 1990, Thiollay 1994). It has been observed in some partially logged tracts of forest, but this is perhaps as a direct result of extensive primary forest loss in the subtropical zone (Thiollay 1994). The species likely requires some undisturbed primary montane forest in at least part of its large home range (Ferguson-Lees and Christie 2001).
Nests are placed in tall trees in dense forest (Rivas-Fuenzalida et al. 2022). The breeding period usually spans the dry season, but may vary geographically and between years; a pair raises one chick every one or two years (Rivas-Fuenzalida et al. 2022). The species feeds on a variety of mammals and birds. Domestic chickens comprise an increasing percentage of prey items (Márquez and Delgado 2010, Aráoz et al. 2017, Restrepo-Cardona et al. 2019).
The species apparently requires at least part of its home range to include undisturbed primary forest, which has been subject to huge losses in many parts of its extensive range, primarily owing to conversion for agriculture (Ferguson-Lees and Christie 2001, Global Forest Watch 2023).
Persecution and poaching has been recorded in Colombia, Ecuador and Peru in response to or as a prevention of predation of domestic chickens (Márquez and Delgado 2010, Renjifo et al. 2014, Rivas-Fuenzalida et al. 2022). It is not known how serious a threat this is, but studies found direct killings in over half of the territories investigated (Márquez and Delgado 2010; Rivas-Fuenzalida et al. 2022, 2023). This conflict appears to be increasing (C. Márquez in litt. 2014), and as larger extensions of forest are colonised, eagles may come into more frequent contact with humans and poultry (Aráoz et al. 2017, Restrepo-Cardona et al. 2019). Collision with powerlines and electrocution is a further threat, though the impacts are currently not believed to be large (Rivas-Fuenzalida et al. 2022).
Conservation Actions Underway
The species occurs in several national parks and other protected areas in Venezuela, Colombia and Ecuador (C. J. Sharpe in litt. 2003, Y. Molina in litt. 2010, H. Vargas in litt. 2012). A conservation and monitoring project on the east slope of the Eastern Andes of Colombia is seeking to identify priority areas for conservation as well as addressing conflicts between poultry owners and eagles (C. Márquez in litt. 2012). It is listed as Endangered at the national level in Colombia, Argentina and Ecuador (Renjifo et al. 2014, MAyDS and AA 2017, Freile et al. 2019) and as Vulnerable in Peru (SERFOR 2018).
Text account compilers
Hermes, C.
Contributors
Benstead, P., Buitron, G., Calvert, R., Capper, D., Clay, R.P., Donegan, T., Herzog, S.K., Mansur, E.F, Molina-Martínez, Y.G., Márquez, C., Sharpe, C J, Symes, A., Taylor, J. & Vargas, H.
Recommended citation
BirdLife International (2024) Species factsheet: Black-and-chestnut Eagle Spizaetus isidori. Downloaded from
https://datazone.birdlife.org/species/factsheet/black-and-chestnut-eagle-spizaetus-isidori on 25/11/2024.
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 25/11/2024.