Archived 2014 discussion: Black-and-chestnut Eagle (Spizaetus isidori): uplist to Endangered?

This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.

BirdLife species factsheet for Black-and-chestnut Eagle

Black-and-chestnut Eagle Spizaetus isidori has an extensive but narrow 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 (Fjeldså and Krabbe 1990, Thiollay 1994, Roesler et al. 2008).  It is classified as Vulnerable under criterion C2a(i), on the basis of a small global population (approximately 1,000-2,499 mature individuals), with all subpopulations  believed to number fewer than 1,000 mature individuals, and a continuing decline as a result of the destruction of its montane forest habitat.

It is thought to be rare and its status is very poorly known (Thiollay 1994, Ferguson-Lees and Christie 2001). 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 of a maximum of 200 mature individuals. The global population has been estimated to be both larger than 1,000 individuals (T. Donegan in litt. 2010, Y. Molina in litt. 2010) or fewer (H. Vargas in litt. 2012); complete surveys of this species throughout its range are needed to accurately quantify its global population.

However, recent sources suggest that no Andean country population contains more than 250 individuals (H. Vargas in litt. 2012). Additionally, the population is considered to be declining as a result of habitat loss (Thiollay 1994) and human persecution (H. Vargas in litt. 2012) throughout its range.  If there is sufficient evidence to suggest that all subpopulations contain ≤250 mature individuals, the Black-and-chestnut Eagle would qualify for uplisting to Endangered under criterion C2a(i) of the IUCN Red List.

For the purposes of Red List assessments, subpopulations are defined as geographically or otherwise distinct groups between which there is little or no demographic or genetic exchange, i.e. typically one successful migrant per year or less.

Comments on the total population size, size of the largest subpopulation and likely population trends of this species are welcomed.


Ferguson-Lees, J. and Christie, D. A. (2001) Raptors of the world. London, UK: Christopher Helm.

Fjeldså, J. and Krabbe, N. (1990) Birds of the high Andes. Copenhagen, Denmark: Apollo Books.

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

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

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6 Responses to Archived 2014 discussion: Black-and-chestnut Eagle (Spizaetus isidori): uplist to Endangered?

  1. Sebastian K. Herzog says:

    In the Armonia data base we have records from 22 localities (excluding a couple of records of apparently wandering birds) in four departments (Chuquisaca, Cochabamba, La Paz, Santa Cruz), and four of these localities are in the same mountain range that could be lumped into one or two localities. Eight of these localities are my records, and I never saw more than 1-2 birds, once or perhaps twice per locality. My cumulative field/bird survey time within the Bolivian range of the species is well over 2 years.

    eBird records are pretty much from the same areas as our data base records, except one or two of them.

    Although it is difficult to convert this information into a population size estimate, I am pretty confident that we most likely have (well) below 250 mature birds in Bolivia.

  2. Carl Downing says:

    Black- and-chestnut Eagle is not a difficult bird to see in Colombia. There is a substantial population in the Santa Marta Mts where I have recorded up to 7 individuals on a single visit to Cerro Kennedy, Magdalena. It is also regularly found on the west slope of the Los Nevados National Park, Risaralda in SFF Otun Quimbaya and higher up in Ucumari Reserve. It also appears common around Monterredondo on the edge of Chingaza National Park, Cundinamarca. There appear to have been no significant reductions in recordings of this species at these sites in 18 years for Risaralda and 13 Years for Magdalena.

  3. Andy Symes says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2014 Red List is to pend the decision on Black-and-chestnut Eagle Spizaetus isidori and keep this discussion open until early 2015, while leaving the current Red List category unchanged in the 2014 update.

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  4. Galo Buitron says:

    My observations in Ecuador suggest that the species seems to be rare and found on scattered locations. I consider that this is also related to the forest conditions. In Ecuador, it is found usually in large tracks of montane forests, but these areas are threatened by logging and mining in Ecuador. Considering that Black and Chestnut Eagle is a large raptor dependent of a good source of medium size preys, a vulnerable category seems to be appropiate considering the rapid loss of pristine habitats in their current range.

  5. Cesar Marquez says:

    We been studying two active nests for the Black and chestnut Eagle one within the Municipality of Gachala (Departamento de Cundinamarca) and the second one within the Municipality of Campohermoso (Departamento de Boyaca) in Colombia. In both places we have observed that there is an incresing conflict with “campesinos” because of the eagle s chicken stilling habits. This has lead to the shooting of adult eagles periodically in these areas by the “affected campesinos”. Whithin the second nest studied and monitored for more than five years, we discovered that the adult pair first reproduced in year 2010 and again reproduced after four years at the beginning of year 2014. In this two events they laid only one egg and raised only one chick. This means a very low reproductive rate indeed. Appart from these, the distance between the two nest is 60 kilometers away. If this could be taken as part of a nest density estimate for this species, this could mean a very low nest density. I estimate that the Colombian adult population for these species is not more than a 100 adult individuals. Although in some isolated subpopulations like in Sierra Nevada de Santa Marta and in Risaralda (Ucumari Reserve) this eagle could be observed, it is quite possible that the same individuals could be observed within different places in the same region in the same day because of their extraordinary flying mobility, which seems to be the case of the Magdalena site mentioned in an earlier comment. I agree that most subpopulations could be well below 250 individuals and that probably the world population is less than 1000 individuals. In accordance to these, I suggest that that the Black and chestnut Eagle should be upgraded as soon as posible to the endangered category.

  6. Andy Symes says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there has been a change to our preliminary proposal for the 2014 Red List status of this species, and the recommended classification to be put forward to IUCN is to treat Black-and-chestnut Eagle as Endangered under criterion C2a(i).

    The final categorisation will be published later in 2014, following further checking of information relevant to the assessment by BirdLife and IUCN.

Comments are closed.