The crowned solitary eagle Buteogallus coronatus is one of the largest and most severely threatened eagles of the Neotropics, categorized as Endangered on the IUCN Red List because of its small and fragmented population (total number of reproductive individuals < 1000), significant range contraction and continuing decline (Canal et al., 2017, Conservation Genetics, 18, 235–240). The main threats to the species include habitat loss, human persecution and electrocution by power lines. Like other large eagles, the species has a naturally low population density, late sexual maturity and low productivity, characteristics that when combined with human-induced threats can drive species to extinction. The crowned solitary eagle inhabits open dry forest and savannahs across central Brazil, eastern Bolivia, Paraguay and northern Argentinian Patagonia (Bird Life International, 2016, datazone.birdlife.org).
Savannah enclaves on the periphery of the Amazon forest comprise heterogeneous mosaics of open areas and forests with a diverse community of both savannah and forest adapted species. These enclaves are coveted by large-scale agriculture, particularly in the southern Brazilian Amazon, which has the highest deforestation rates in the country. During February 2017—February 2019 we conducted extensive surveys in this region, including in Campos Amazônicos National Park, which was created in 2006 to protect the largest Amazonian savannah enclave (434,200 ha) in the southern Brazilian Amazon. Within this enclave, during the dry season, we recorded a single adult crowned solitary eagle at 61.818 °W 8.478 °S, at least 600 km outside the species' known range. The record reported here is the most northerly known record of the species. Although unexpected because of the distance from documented populations, the area has large tracts of natural open habitats similar to those used by the crowned solitary eagle elsewhere.
Even though eagles have high dispersal capabilities, the great distance from other known populations suggests that this record is not a dispersing individual. However, further studies are needed to confirm whether there is a resident population within this savannah enclave. As documented for species elsewhere (Hody & Kays, 2018, ZooKeys, 759, 81–97), it is possible that the crowned solitary eagle is expanding its distribution northward, following substantial landscape transformation in this region from Amazonian forest to open areas for extensive cattle ranching. A number of recent records from extensive cattle-ranching areas (Bird-Life International, 2016) suggests that the species is capable of tolerating disturbances associated with this anthropogenic habitat, although the species is persecuted by ranchers (Barbar et al., 2016, Journal of Raptor Research, 50, 115–121).
The existence of a resident population or pioneer colonists of the crowned solitary eagle would be good news both for the species and for Campos Amazônicos National Park, which faces severe challenges to the maintenance of its integrity, with various infrastructure projects planned or ongoing nearby, including roads, hydroelectric dams and mining. The presence of the crowned solitary eagle emphasizes the biodiversity value of this poorly studied region.
