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Black-and-chestnut Eagle Spizaetus isidori

This species is considered Vulnerable as it has a small population, with all sub-populations believed to number fewer than 1,000 mature individuals, which is undergoing continuing decline as a result of the destruction of its montane forest habitat as well as direct human persecution. Further research is required to elucidate threatening processes and quantify their resulting effects on population trends.

Taxonomic source(s)
SACC. 2006. A classification of the bird species of South America. Available at:
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

Taxonomic note
Oroaetus isidori (Sibley and Monroe 1990, 1993) is transfered to the genus Spizaetus following SACC (2006).

Oroaetus isidori Collar and Andrew (1988), Oroaetus isidori Collar et al. (1994), Oroaetus isidori BirdLife International (2004), Oroaetus isidori Sibley and Monroe (1990, 1993), Oroaetus isidori Stotz et al. (1996), Oroaetus isidori

Distribution and population
This species has an extensive but narrow and altitudinally restricted linear distribution on the coastal ranges of north-central Venezuela (Carabobo and Aragua) and north-east 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-west Argentina (Fjeldså and Krabbe 1990, Thiollay 1994, Roesler et al. 2008). It is thought to be rare and patchily distributed but its status is very poorly known (Thiollay 1994, Ferguson-Lees and Christie 2001). A recent population estimate indicated that the total population may not exceed 1,000 individuals (Ferguson-Lees and Christie 2001), however, the Venezuelan population is estimated to be in the low hundreds (C. J. Sharpe in litt. 2003), a maximum of 200 individuals are estimated to reside in Ecuador (Ridgely and Greenfield 2001), and a large stretch of suitable habitat on the eastern slopes of the Andes in Colombia, from Huila to Meta department, is also thought to hold a few hundred individuals (T. Donegan in litt. 2010). The population in Argentina may be small (Ferguson-Lees and Christie 2001), and whilst there is an unquantified number in Peru and Bolivia, it remains rare. 

Population justification
The population in Venezuela has been estimated in the low hundreds (C. J. Sharpe in litt. 2003). Opinions on the population in Colombia differ: one population alone is thought to support a few hundred individuals (T. Donegan in litt. 2010), or the total population may be fewer than 100 adults (C. Márquez in litt. 2012). The population in Ecuador is thought to consist a maximum of 200 mature individuals. The global population has been estimated to be larger than 1,000 individuals (T. Donegan in litt. 2010, Y. Molina in litt. 2010) or fewer than this (H. Vargas in litt. 2012). Given that further populations exist both in Colombia and in other range countries, it is reasonable to estimate a population of 1,000-2,499 mature individuals. This equates to 1,500-3,749 individuals in total, rounded here to 1,500-4,000 individuals. However, a complete survey of this species throughout its range is needed to accurately quantify its global population.

Trend justification
This species is thought to prefer primary forests (C. J. Sharpe in litt. 2003, T. Donegan in litt. 2010), although it may persist in mosaics of primary and secondary forest with open areas (C. Márquez in litt. 2012). Given habitat loss (Thiollay 1994) and persecution by humans (H. Vargas in litt. 2012) throughout its range, the population is considered to be declining.

It is found on heavily forested mountain slopes, probably occurring mostly in large valleys, usually at 1,500-2,800 m, but recorded from sea-level to 3,500 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). Despite such observations, it is considered that the the species requires some undisturbed primary motane forest in at least part of its large home range (Ferguson-Lees and Christie 2001). It has been recorded feeding on a variety of mammals and birds, and its breeding season in Colombia and Bolivia is thought to be between February and September (Ferguson-Lees and Christie 2001). Chickens comprised over a third of prey items at one nest in Colombia (Márquez and Delgado 2010).

It 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 due to conversion for agriculture (Ferguson-Lees and Christie 2001). Persecution has been recorded in Colombia and Ecuador in response to predation of chickens (Márquez and Delgado 2010, Y. Molina in litt. 2010). It is not known how serious a threat this is, but in one Colombian study, eight cases of eagle persecution and killing were noted (Márquez and Delgado 2010). As larger extensions of forest are colonised, eagles may come into more frequent contact with humans and livestock (C. Márquez in litt. 2012, H. Vargas in litt. 2012).

Conservation Actions Underway
It 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 chicken owners and eagles (C. Márquez in litt. 2012).
Conservation Actions Proposed
Research its ecological requirements and tolerance of habitat fragmentation. Attempt to obtain an accurate global population estimate of this difficult to survey species. Expand network of protected areas to include large core areas of mountain slope primary forest. Investigate methods to protect backyard chickens from eagle predation (C. Márquez in litt. 2012, H. Vargas in litt. 2012).

Ferguson-Lees, J.; Christie, D. A. 2001. Raptors of the world. Christopher Helm, London.

Fjeldså, J.; Krabbe, N. 1990. Birds of the high Andes. Apollo Books, Copenhagen.

Marquez, C.; Delgado, H. 2010. Feeding ecology and conservation of Isidor's Eagle (Spizaetus isidori) in Colombia. The Peregrine Fund Reports. The Peregrine Fund, Boise, Idaho, USA.

Ridgely, R. S.; Greenfield, P. J. 2001. The birds of Ecuador: status, distribution and taxonomy. Cornell University Press and Christopher Helm, Ithaca and London.

Salaman, P. G. W.; Donegan, T. M.; Cuervo, A. M. 1999. Ornithological surveys in Serranía de los Churumbelos, southern Colombia. Cotinga 12: 29-39.

Thiollay, J.-M. 1994. Family Accipitridae (Hawks and Eagles). In: del Hoyo, J.; Elliott, A.; Sargatal, J. (ed.), Handbook of the birds of the world, pp. 52-205. Lynx Edicions, Barcelona, Spain.

Text account compilers
Benstead, P., Calvert, R., Capper, D., Clay, R., Mansur, E., Sharpe, C J, Symes, A.

Donegan, T., Molina-Martínez, Y., Sharpe, C J, Zuluaga, Z., Márquez, C., Vargas, H., Calderón, D.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Spizaetus isidori. Downloaded from on 16/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 16/04/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Vulnerable
Family Accipitridae (Osprey, kites, hawks and eagles)
Species name author (Des Murs, 1845)
Population size 1000-2499 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 469,000 km2
Country endemic? No
Links to further information
- Additional Information on this species