Data Zone
Justification of Red List category
This species is believed to have a very small global population size, comprising 800-2,000 mature individuals, all of which are in a single large subpopulation. It is believed to be declining because of forest loss, hunting and electrocution. It is therefore assessed as Endangered.
Population justification
This species occurs at a low density throughout its wide range. In the state of Paraná, Brazil, the population is estimated, based on observations by experienced observers over the past decade, at 20-22 birds, including some that likely range into neighbouring states (Scherer-Neto et al. 2023, ICMBio 2023). As the state of Paraná makes up 2.5% of the species’ EOO, a naïve extrapolation of this population would give a total global population of 800-880 birds (B. Phalan, P. Scherer-Neto and T. Bichinski in litt. 2024). However, it is not known if density in Paraná is representative of other parts of the range. A conservative assumption can be made that it is lower, as most of the western half of the state has been converted to soybeans, maize, pasture and other agricultural uses – however, it should be noted that this is also true of other large areas within this species’ range in the Cerrado, Chaco and Pampas. Even assuming that half of Paraná is entirely unsuitable, and as such that the density in other parts of the range is twice as high, extrapolation to the entire range would give an estimate of 1,600-1,760 birds (B. Phalan, P. Scherer-Neto and T. Bichinski in litt. 2024). Given also that some individuals will be immature, the true number of mature individuals is likely be lower than this estimate. This is consistent with the estimate of 600-1,000 mature individuals in Brazil reported by Marini et al. (2023) based on the number of points of occurrence registered (around 300), accounting for the fact that some territories and individuals will not have been reported. This would imply a global population of 1,200-2,000, though may be an overestimate given that multiple points of occurrence across a wide area can refer to the same individual or pair (B. Phalan, P. Scherer-Neto and T. Bichinski in litt. 2024). The global population of this species is therefore estimated to number 800-2000 mature individuals.
Trend justification
Apart from suffering from habitat loss, the species is also experiencing direct mortality through persecution and electrocution. Population declines are ongoing, as evidenced by a genetic study detecting a recent bottleneck (Canal et al. 2017). Habitat conversion, using ongoing tree cover loss as a proxy (Global Forest Watch 2023), is extensive throughout the range. However, this species also occurs in other habitats including natural savannas, semi-arid areas and grasslands. Loss of natural grasslands in southern Brazil (Santa Catarina and Rio Grande do Sul) was estimated at 20% from 1985 to 2018 (ICMBio 2023). Electrocution by powerlines is a substantial threat to the species, with high rates of mortality in both adults and juveniles (Galmes et al. 2018, Sarasola et al. 2020). A study in central Argentina found electrocution on a specific type of pylon to cause mortality rates of roughly 3% per year (Galmes et al. 2018). Shooting and deliberate disturbance are a substantial threat at least in Argentina and Brazil, where the species is persecuted for attacks on livestock (Sarasola and Maceda 2006, Sarasola et al. 2010, Barbar et al. 2016, Marini et al. 2023). The impact of hunting on the population has not been quantified. Additionally, this species has low breeding success, takes 4-6 years before reproducing for the first time and produces at most one offspring during a successful breeding season (Zorzin et al. 2021, ICMBio 2023, B. Phalan, P. Scherer-Neto and T. Bichinski in litt. 2024). Overall, given the intensity of threats, population declines may well be fast, and a quantification of the trend rate is urgently required.
Buteogallus coronatus has a very large range from central Brazil, Bolivia and Paraguay to central Argentina. There are no unequivocal records in Uruguay (Azpiroz and Cortés 2014).
B. coronatus inhabits lowland and foothill areas of semi-open seasonal dry country (palm-savanna, sparse woodland, steppes with bushes), chaco and campo cerrado (from campo limpo to cerrado sensu stricto). It has also been reported in caatinga, gallery forest, marsh and buriti groves. Moreover, there are a records from extensive cattle ranches (H. del Castillo in litt. 2007). Despite its occurring in mostly open areas it requires tall trees for nesting; a large platform nest is situated in trees and one egg is laid. Reported foods include mammals, birds, reptiles, carrion and fish (R. P. Clay in litt. 2000), but in La Pampa, Argentina, armadillos and snakes and were the most important prey (Sarasola et al. 2010). The species has high dispersal abilities; a genetic study found the population to be panmictic (Canal et al. 2017). The home range of pairs or adults can be 500-600 km2, and juveniles can disperse over an area of 12,000 km2 during their dispersal period (Barbar et al. 2016, Marini et al. 2023).
The most pertinent threats to the species are habitat loss, hunting and electrocution.
In large parts of the range, campo cerrado habitats are being rapidly destroyed by mechanised agriculture, intensive cattle-ranching, afforestation, invasive grasses, excessive use of pesticides and annual burning (Stotz et al. 1996, Parker and Willis 1997, Marini et al. 2023). Chaco habitats appear more intact, but increasing colonisation is destroying wooded areas and grassland. The species is described as sensitive to converted and degraded habitats (Marini et al. 2023), even though records suggest that it may be able to use extensive cattle ranches where it is not subjected to disturbance (H. del Castillo in litt. 2007).
Electrocution by powerlines is a substantial threat to the species, with high rates of mortality in both adults and juveniles (Galmes et al. 2018, Sarasola et al. 2020). Shooting and deliberate disturbance are a substantial threat, at least in Argentina and Brazil where the species is persecuted for attacks on livestock (Sarasola and Maceda 2006, Sarasola et al. 2010, Barbar et al. 2016, Marini et al. 2023). Individuals have also been rescued with serious injuries as a result of collision with kite strings (B. Phalan, P. Scherer-Neto and T. Bichinski in litt. 2024). Moreover, there appears to be some trapping for the illegal trade in Argentina (R. Pereyra in litt. 2012). Nest abandonment because of human activities, and the apparent killing of a fledgling by domestic dogs have also been reported (Zorzin et al. 2021).
Conservation Actions Underway
CITES Appendix II. It is protected in Argentina and Paraguay, and hunting is prohibited in Brazil and Paraguay. It occurs in several protected areas across its range. It is listed as Endangered at the national level in Bolivia, Argentina and Brazil (Ministerio de Medio Ambiente y Agua 2009, MAyDS and AA 2017, Marini et al. 2023).
Conservation Actions Proposed
Quantify and monitor the population trend. Study the impact of threats on the population.
Protect areas of suitable habitat within the range. Promote establishment of ecological corridors to reduce habitat fragmentation. Develop and establish educational and awareness campaigns to limit hunting near key populations. Enforce legal protection of the species. Promote retrofitting of powerlines and pylons, especially in breeding territories.
75-85 cm. Large, powerful, crested eagle. Long, broad wings with short tail. Dull slaty-grey, slightly darker on wings. Prominent bushy crest. Dusky tail with white band and tip. Yellowish legs and cere. Immature brown above with creamy head and dark post-ocular stripe. Cream throat and underparts, mottled brown on upper breast. Brown tarsi and mottling in lower belly. Similar spp. Great Black Hawk Buteogallus urubitinga lacks crest, is smaller and shorter-winged. Adult blacker, immature more heavily streaked brown below. Voice Powerful, long high-pitched whistle.
Text account compilers
Vine, J., Hermes, C.
Contributors
Baumgarten, L., Benstead, P., Capper, D., Clay, R.P., De Luca, A., Develey, P., Galmes, M., Mazar Barnett, J., Pereyra , R., Sarasola , J., Sharpe, C.J., Silveira, L.F., Symes, A., del Castillo, H., Bichinski, T., Scherer Neto, P. & Phalan, B.
Recommended citation
BirdLife International (2024) Species factsheet: Crowned Solitary Eagle Buteogallus coronatus. Downloaded from
https://datazone.birdlife.org/species/factsheet/crowned-solitary-eagle-buteogallus-coronatus on 21/12/2024.
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 21/12/2024.