Chaco Eagle needs help to avoid extinction!

Chaco Eagle needs help to avoid extinction! 

¡El Águila Coronada necesita ayuda para evitar su extinción!

Hello everyone! We are Diego Gallego, Beatriz Martínez-Miranzo and José Hernán Sarasola. We are biologists at the Center for the Study and Conservation of Birds of Prey in Argentina (CECARA), a group of scientists that contribute to the protection and conservation of raptors. As top avian predators, raptors play a key role in ecosystems, but require large areas of habitat, making them extremely susceptible to changes in land use and human disturbance. As a result, a great number of raptor species are currently listed as threatened.

 

The Chaco Eagle

The Chaco Eagle (Buteogallus coronatus) is one of the rarest and most severely threatened birds of prey the Neotropical region. It is one of the largest raptors in all southern South America, reaching a wingspan of up to six feet (180 cm), and weighing nearly nine pounds (4500 g). Adults have grey to ash-colored plumage, and a conspicuous crest on the head.

 

 

The species inhabits a variety of forested habitats, including savannah-like ecosystems, open woodlands and dry shrublands, from southern Brazil, Bolivia, and Paraguay to central Argentina. It takes four to five years for this eagle to mature to breeding age and has a low productivity rate, producing only one egg per nesting season. Unfortunately, it is listed Endangered by the International Union for the Conservation of Nature (IUCN), with a world population estimated at less than 1,000 reproductive individuals as populations continue to decline. The Chaco Eagle is considered extinct in Uruguay, where it has not been reported since the 1930s.

 

Main threats for Chaco Eagle conservation

The primary threats to Chaco Eagle populations are mostly human-related. First, the species appears highly sensitive to broad-scale habitat transformations of native forests into croplands, but the effects on Chaco Eagle populations have not been assessed. The species also suffers from illegal killing by locals, another key source of mortality, with more than 100 incidents reported across Argentina. This direct persecution is based on traditional beliefs that the species preys on livestock, but in Argentina, the Chaco Eagle diet mainly consists of armadillos and reptiles such as tegus, pit vipers and coral snakes.

 

 

 

Other important causes of mortality are related to human infrastructures. On the one hand, Chaco Eagle individuals can be electrocuted in power line poles where they perch while hunting for food. On the other hand, they are also at risk of drowning in open-pit water reservoirs that are common in farmlands and ranches of arid habitats.

 

 

Despite its wide range of distribution and its critical conservation status, few studies exist on Chaco Eagle, and many aspects of its biology remain unknown, including habitat use and dispersal behavior. Unfortunately, it is not easy for Chaco Eagle populations to recover: added to the fact that they only lay one egg per reproductive attempt, more than half of the nests fail. Even worse, when the fledglings successfully leave the protection of their parents, they face a 4-year stage, known as dispersal, and only 30% survive. With all this in mind, statistical models predict a probable extinction of this endangered species in the next 50 years. The disappearance of this apex predator could eventually result in an uncontrolled increase in the populations of its preferred prey species, such as venomous vipers and armadillos, with unknown consequences to other wildlife and the ecosystem.

Chaco Eagle Project

Twenty years ago, little was known about Chaco Eagles. Thanks to a few long-term studies, particularly in central Argentina, new scientific information about Chaco Eagle ecology has emerged and provided some insight into threats affecting their populations. Milestones include a change in people´s perception towards Chaco Eagle and a subsequent decrease in the illegal killing in La Pampa province (the southernmost of its distribution area). In 2019, a beautiful initiative of which I am part, Chaco Eagle Project, was founded. Its main objectives are (1) to increase our knowledge on its status and ecology and gain more knowledge on unknown aspects of its biology and behavior, (2) to promote social awareness on the main threats for its decline, (3) to implement mitigation measures to reduce human-related mortality and (4) to create a network of enthusiasts committed with its conservation, including landowners, ornithologists, land management technicians and other professionals of nature.

 

 

Proof of the hard work that we have been developing in recent years are the conservation and outreach programs that we have carried out in different provinces of Argentina, funded by some foundation gifts and grants. However, before additional education and conservation is conducted we need to fully understand the extent and relevance of the threats that make the future of this species uncertain.

 

Plans and Goal

Research on the Chaco Eagle is imperative to build baseline knowledge on the movement ecology, habitat use, and sources of mortality of juveniles during the most critical period of their life, dispersal. Work to date includes having tagged more than 25 Chaco Eagle fledglings with solar-powered GPS-satellite transmitters during the past years.

 

 

With an estimated transmitter lifetime of 7-8 years, these devices precisely mark the location of the individual hourly. Marked juveniles provide vital information on their movements and survival. Additionally, some tagged juveniles have survived their dispersal period and, as breeding adults, they currently provide us the location of their nests, which are otherwise very difficult to find. To fully understand the changes needed to improve juvenile survival and ensure recruitment into the adult breeding population for this endangered eagle, we need to follow each marked bird for at least 6 years. Unfortunately, the detailed data collected by the transmitters comes at an annual cost of $780 per bird and funding for this project has ended. We must continue to sponsor the transmitters to support ongoing monitoring to maintain the vital satellite data for this endangered raptor.

 

 

Budget

The budget includes two years of monitoring on 14 individuals. All field work and analyses will be covered by the CECARA organisation and myself, and the findings are part of my PhD Thesis, scheduled for 2024: “Natal dispersal and habitat selection of Chaco Eagle (Buteogallus coronatus) in semiarid environments of central Argentina”. We believe this work will build a foundation for future research addressing movement ecology of the endangered Chaco Eagle and future conservation and education actions to improve the status of the eagle in Argentina. Findings from this research will be shared with the international and local conservation community.

 

Some organisations that have funded us include Prince Bernhard Nature Fund (PBNF), The Rufford Foundation, The Whitley Foundation (WFN) and The Raptor Research Foundation (RRF). Other collaborators include the UNLPam (Universidad Nacional de La Pampa) and CONICET (Argentinian Scientific and Technical Research Council).

 

To support this important research on the endangered Chaco Eagle, please consider a gift to our GoFundMe campaign and share it!

 

In the name of the Chaco Eagle, thank you very much for your support!