A comprehensive review of the endangered Black-and-chestnut Eagle (Spizaetus isidori) of South America

BOW Team November 24, 2022
Black-and-chestnut Eagle in flight, Peru. © Tomás Rivas Fuenzalida | Fundación Ñankulafkén
Black-and-chestnut Eagle, Peru

Black-and-chestnut Eagle in flight, Peru. © Tomás Rivas Fuenzalida | Fundación Ñankulafkén

Raptors – or birds of prey – play a critical role in ecosystem balance by stabilizing the food web, promoting biodiversity, and serving as environmental barometers. Despite their importance, raptor populations have suffered significant declines and some have been driven to extinction. Large raptors are especially vulnerable to extinction because they require vast areas of suitable habitat to thrive. Apart from scavengers, the raptors most likely to be at-risk, and thus given a higher priority for research and conservation, are forest-dependent species with confined distributions and long generation times.

Adult female Black-and-chestnut-Eagle captured for banding and satellite transmitter installation, Argentina © Tomás Rivas Fuenzalida | Fundación Ñankulafkén
Adult female Black-and-chestnut-Eagle captured for banding and satellite transmitter installation, Argentina © Tomás Rivas Fuenzalida | Fundación Ñankulafkén

The Black-and-chestnut Eagle (Spizaetus isidori) is a large apex predator (63–74 cm; 2–3.5 kg) endemic to South American montane cloud forest, which is narrowly distributed along the wooded slopes of the Andes and nearby mountain ranges (1000–3500 m) of Venezuela, Colombia, Ecuador, Peru, Bolivia and northern Argentina (11°N–28°S). Despite its continental distribution, S. isidori is one of the lesser-known Neotropical raptors and is classified as Endangered by the IUCN.

Black-and-chestnut Eagle in the nest, Peru @Tomás Rivas Fuenzalida | Fundación Ñankulafkén
Black-and-chestnut Eagle in the nest, Peru © Tomás Rivas Fuenzalida | Fundación Ñankulafkén

S. isidori has been affected by intense deforestation across much of its range; one estimate suggests the total habitat loss in Colombia is up to 60%. In several countries, the species is persecuted by humans in retaliation for poultry depredation. Due to these and other anthropogenic pressures, in 2001 its global population was estimated to be less than 1,000 mature individuals; it’s expected to be much lower today. The most studied aspects of the species are its trophic ecology as well as the breeding ecology based on found nest sites in Colombia, Ecuador, Bolivia, and Argentina. Recently, research expeditions in Ecuador, Peru, and Argentina have quadrupled the number of known breeding sites, providing the basis for population-level ecological studies.

In this all-new, comprehensive review for Birds of the World, authors Tomás Rivas-Fuenzalida, Juan Manuel Grande, Sebastián Kohn, Félix Hernán Vargas and Santiago Zuluaga Castañeda update the status of knowledge of the species, including unpublished information and works in preparation. This was achieved thanks to the work carried out over the last decade by institutions dedicated to the research and conservation of birds of prey in South America, including the Fundación Cóndor Andino (Ecuador), Fundación Proyecto Águila Crestada (Colombia), the Colaboratorio de Biodiversidad, Ecología y Conservación (Colbec, Argentina), The Peregrine Fund (USA) and Fundación Ñankulafkén (Chile). These organizations are currently working in a large-scale, long-term project to study and conserve the Black-and-chestnut Eagle in South America.

We appreciate the work of these individuals and their organizations on the work of these magnificent raptors. We are also excited to announce our new partnership with Fundación Ñankulafkén, who will be contributing expert content on these and other raptor species to Birds of the World.

 

About Fundación Ñankulafkén:

Fundación Ñankulafkén is a non-profit organization whose mission is to promote the conservation and knowledge of threatened or little-known birds of prey in Chile and other Neotropical countries. To this end, it carries out research and conservation projects, focused mainly on forest-dwelling raptors, such as the Rufous-tailed Hawk (Buteo ventralis), the White-throated Hawk (Buteo albigula), the Chilean Hawk (Accipiter chilensis), the Black-and-chestnut Eagle (Spizaetus isidori), the Black-and-white Hawk-Eagle (Spizaetus melanoleucus), the Black Hawk-Eagle (Spizaetus tyrannus), and the Orange-breasted Falcon (Falco deiroleucus). This work has been carried out in Chile, Argentina, Peru and Ecuador, where the Ñankulafkén team has found the largest breeding populations in the world for these species. If you are interested in supporting or learning more about the conservation work of the Fundación Ñankulafkén, contact them via email: contacto@ñankulafken.cl.

Juvenile Black-and-white Hawk Eagle, Peru. © Tomás Rivas Fuenzalida | Fundación Ñankulafkén
Juvenile Black-and-white Hawk Eagle, Peru. © Tomás Rivas Fuenzalida | Fundación Ñankulafkén