Mexico’s first black-and-white hawk-eagle nest is a treasure trove for researchers

The black-and-white hawk-eagle is a little-researched and poorly known species in Mexico, where scientists have described it as a “ghost” because of the sheer scarcity of sightings.
In 2020, researchers in the country’s Lacandon Jungle found a nest used by a breeding pair — the first known black-and-white hawk-eagle nest in Mexico — and monitored its nesting and parenting behavior over the next three years.
The main threat to the species is the loss of its lowland forest habitat, which in this part of Mexico is driven largely by the clearing of forest to make way for livestock pasture.

It was a tourist who first found the nest. It was March 2020, and the visitor was walking through the Lacandon Jungle in southern Mexico. When he reached the highest point, he looked up and pointed to a shelter made of long, thin branches on top of a tree. Fiorella Ortiz, the biologist in charge of the sightseeing tours at the Tamandua ecotourism camp, got out her binoculars to verify the finding. The bird she saw looked odd, so she took a picture of it and sent it to her colleagues.

“We said, ‘It’s the black-and-white hawk-eagle. Stop everything, we need to be there now!’ It’s the first known nest in Mexico,” says Alan Monroy-Ojeda, a tropical ecologist.

Monroy-Ojeda is the scientist responsible for the Mexican Harpy Eagle Initiative, a project led by the organizations Dimensión Natural and Natura Mexicana to study priority raptor species, protect the ecosystems in which they live, and empower the surrounding communities.

The breeding pair of black-and-white hawk-eagles carry dry, green branches to the nest platform. According to researchers, the birds may do this to have a fresh nest or even because the branches have insect-repelling properties. Image courtesy of Santiago Gibert Isern.

The black-and-white hawk-eagle (Spizaetus melanoleucus) is one of six neotropical birds of prey that the initiative studies. The others are the harpy eagle (Harpia harpyja), the ornate hawk-eagle (Spizaetus ornatus), the black hawk-eagle (Spizaetus tyrannus), the crested eagle (Morphnus guianensis) and the king vulture (Sarcoramphus papa). All are considered endangered by Mexican conservation authorities.

“We know of more active golden eagle nests in Mexico than of these tropical eagles together,” Monroy-Ojeda says, referring the species Aquila chrysaetos that’s found throughout the Northern Hemisphere, not just in the neotropics. “Regarding the conservation efforts in the country, there’s a major neglect of these other eagles.”

Monroy-Ojeda traveled with Santiago Gibert Isern, director of Dimensión Natural and the initiative’s chief photographer, to the Tamandua Camp Conservation Area. The camp sits in the Flor del Marqués ejido, or communally managed farmland, in the southern state of Chiapas. It’s one of several sites where this team of scientists has worked with birds for more than 10 years now.

During the early morning hours, the male remains on his usual perch, probably surveying the territory or searching for potential prey. The tree he uses stands out from the canopy, from where he has a direct view of the nesting platform. Image courtesy of Santiago Gibert Isern.

The camp members and the group of scientists built a wooden platform about 30 meters (100 feet) from the tree with the eagle’s nest, allowing them to start monitoring the birds. “And just like that, Santiago and I would observe it, half-hidden. He would climb and use his cameras to document [the eagles]. I would go after and observe, but we were both investigating its behavior,” Monroy-Ojeda says.

The black-and-white hawk-eagle is “almost a ghost,” he says. In the scientific literature, there are records of only four other nests — in Brazil, Suriname and Panama — which makes this species one of the least-documented birds of prey in the tropical Americas.

The great forest of the Lacandon Jungle is one of the last remaining habitats with sufficient resources to support thriving populations of neotropical raptors. Image courtesy of Santiago Gibert Isern.

The black-and-white hawk-eagle mystery

The hawk-eagle’s gaze is deep and piercing, and its eyes are an intense yellow surrounded by a black hood. “If you look at it long enough, you have the feeling that it’s going to come for you,” Monroy-Ojeda says. He lists off its prey: toucans, pigeons, partridges, as well as mammals, reptiles and amphibians, all of which it hunts with a breathtaking dive from the air. It’s the ultimate apex predator.

“It has almighty claws and one of its modus operandi when hunting is to go high in the sky, stop and plunge. It kills the birds that are flying above the canopy with a strike. We have seen it hunt and it’s pretty fascinating,” Monroy-Ojeda says.

Researcher Alan Monroy-Ojeda takes a tour inside Montes Azules Biosphere Reserve in Chiapas. High on his list of priorities is the observation of active nests of neotropical raptors and their parenting behavior. Image courtesy of Santiago Gibert Isern.

Male and female black-and-white hawk-eagles are very similar, unlike most other birds of prey where the females tend to be larger. The adults vary in length from 51-58 centimeters (20-23 inches) and weigh between 750 and 780 grams (26.4 and 27.5 ounces). They have a short, round, black crest, and while their head, neck and underparts are white, their entire dorsal region is covered in a glossy black coat. Their tarsus, the section of the leg from the ankle to where the toes begin, is feathered, unlike in other eagles, which is bare. Their talons are unusually long, disproportionately so for the bird’s size.

While considered endangered in Mexico, the species has an extensive range stretching south to Argentina, and as such has a conservation status of least concern on the IUCN Red List. Nevertheless, the IUCN, the global wildlife conservation authority, notes a declining population trend for the species.

A watercolor painting by Alan Monroy-Ojeda, based on his observations of the black-and-white hawk-eagle and its surroundings. Image courtesy of Alan Monroy-Ojeda.

Dimensión Natural helped draw up a Program of Action for the Conservation of Species (PACE by its Spanish acronym) that was published by the Mexican Secretariat of Environment and Natural Resources and National Commission for Protected Areas. It covers the neotropical eagles and the king vulture, and describes the black-and-white hawk-eagle as being considered rare and threatened across the countries that make up its range. In Mexico, most sightings of the bird are in the country’s southeast, where their preferred habitat is lowland tropical forest.

Habitat fragmentation is one of the main threats to neotropical birds of prey. Slash-and-burn agriculture is widespread in Mexico’s tropical regions as a quick way of clearing rainforest for pasture, rendering these areas uninhabitable for wildlife. Image courtesy of Santiago Gibert Isern.

The main threats to this species are the fragmentation of its habitat and deforestation. There are other dangers, like poaching, theft of nestlings and eggs from nests for the illegal wildlife trade, and pesticide poisoning when eating tainted prey.

“The threats are the same for these six species of neotropical birds” that the Mexican Harpy Eagle Initiative, Gibert Isern says. “The most significant one is forest loss due to the development of the agricultural frontier.”

Forest is cut down, burned, and turned into pasture, he says. “There’s also illegal logging, which affects the eagles as their nests are always in emergent trees that stand out from the average height of the rest of the forest. Many times, illegal logging targets the trees the eagles use,” he says.

Heavy machinery on the banks of the Lacanhá River in the Lacandon Jungle. Workers quarry stone and gravel from the riverbed for construction, but this extraction alters the river’s characteristics and can have unexpected adverse effects on the conservation of natural areas. Image courtesy of Santiago Gibert Isern.

Researchers say the black-and-white hawk-eagle used to nest across a wide swath of Mexican forest, but this range began shrinking rapidly. “The eagle had no other choice than to stay there, in the Tamandua Camp Conservation Area, in the Lacandon Jungle,” Monroy-Ojeda says. “We don’t know how many years that pair of eagles has been nesting there, but the forest has been shrinking for sure. We hope we can keep it as it is or even reverse the process.”

Looking for a chance to survive

The nest spotted by the tourist in March 2020 was up in an emergent tree, towering about 25 m (82 ft) high, well above the canopy. That’s where the team focused its observations over the next three years, knowing that the species has a habit of nesting annually in the same place if it’s not altered.

The sighting by the tourist constituted the first observed nesting attempt. The researchers then started their monitoring and trained all the tourist guides from the Tamandua Camp on how to monitor and surveil the hawk-eagles. Because the guides were already knowledgable in nature tourism, eco camps and conservation, they were the best candidates to keep track of developments at the nest. However, the nesting attempt that year failed for unknown reasons.

The black-and-white hawk-eagle nestling waits for the arrival of one of its parents to feed it. The black spots on its back denote the appearance of the first true feathers. Image courtesy of Santiago Gibert Isern.

A year later, in March 2021, the female succeeded in hatching an egg. “Santiago managed to take pictures of the baby bird but by May it was no longer there. They don’t become independent that quickly, so we believe that something happened,” Monroy-Ojeda says. The hatchling likely died from a predator attack or falling from the nest, the researchers say.

In 2022, there was a third nesting attempt, and this time it was successful. The mother hatched the egg, the hatchling grew bigger, and “We started seeing it jump through the tree, then in between trees and almost a year later, in 2023 we could see it flying above the nest as a fledgling,” a bird that is flying for the first time. Monroy-Ojeda says. “That is what we consider a successful nesting.”

During this process, the researchers were able to discover interesting aspects of the species’ feeding habits. “We recorded what they eat. For example, we wrote what the mother would bring in between its claws when it got to the nest,” Monroy-Ojeda says. “We also did checkouts below the nest area where we picked up feathers and bones to see which species are suffering alterations at the ecosystem level and what their interactions are.”

During this observation period, the team was also able to identify the hawk-eagle’s diet. There were chachalacas (Ortalis spp.), a quail-like bird, and emerald toucanets (Aulacorhynchus prasinus), as well as mammals such as squirrels and coatis (Nasua narica).

After several weeks of constantly caring for the nestling, the female takes it on its first flight. From this moment on, the couple will take turns caring for the nestling and doing different chores. Image courtesy of Santiago Gibert Isern.

By the time the 2023 nesting season rolled around, the breeding pair were trying again. This time, however, their nest fell off the tree because of strong wind gusts. Despite this, they didn’t give up. Soon after, the birds started to reconstruct their nest “probably to do a new nesting in 2024,” Monroy-Ojeda says. “This story teaches us that even though it’s a protected and monitored area, there are natural conditions that make it so that survival can’t be 100%,” he adds. “This species was already threatened, [so] if we add these conditions, we have a species that needs to be even more protected.”

To ensure the survival of the breeding pair, the nest is now under permanent surveillance by Uriel Alexander Morales, a technician and trained guide from the Tamandua Camp, and Jorge Alfonzo Mátuz, a Natura Mexicana field biologist.

The latter organization’s role was crucial for the success of the study of the black-and-white hawk-eagle in the Lacandon Jungle — a region that the Secretariat for the Environment and Natural Resources considers a genetic reservoir because of its megadiversity, including 345 recorded species of birds.

Researchers Alan Monroy-Ojeda and Jorge Alfonzo Mátuz, members of the Mexican Harpy Eagle Initiative, monitor the canopy of the Lacandon Jungle in search of new breeding pairs of the six species of neotropical raptors of conservation concern. Image courtesy of Santiago Gibert Isern.

“Natura Mexicana has been working for many years on the ejido where the black-and-white hawk-eagle nest is. Thanks to Javier, new opportunities arose where we were able to study and preserve the species in the Lacandon,” Monroy-Ojeda says. Javier de la Maza was a biologist and head of Natura Mexicana whose work led many ejidos to carry out conservation actions in areas adjacent to reserves. He died in July 2023.

“Javier planted the seed in these communities and it’s thanks to them that there are still large areas of the tropical forest in the Lacandon, where we may find neotropical raptors,” Monroy-Ojeda says.

The difficulty of protecting a raptor

Getting photos of the “ghost bird” was the biggest and most important success in the last three years of monitoring in the Lacandon Jungle. Santiago Gibert Isern’s work as a photographer has been key for the scientific recording of the black-and-white hawk-eagle.

He says he knows that when the female calls out from the nest to see where the male is, the latter will invariably show up with prey. So he stands ready with his camera at a distance, taking pictures of the moment when the male reaches the nest. Then he analyses the pictures on the monitor to identify the most important elements, including the prey species that constitute the hawk-eagle’s diet.

The black-and-white hawk-eagle nestling waits for the return of one of its parents to feed it. At this stage, the female no longer stays in the nest around the clock, and has instead begun to go out into the tree canopy to hunt. Image courtesy of Santiago Gibert Isern.

“We do something called conservation photography given that we are a partnership: Alan is the researcher and I’m the photographer. We provide feedback to each other to generate information and vital points,” Gibert Isern says. And like that, they came up with the action program for the conservation of neotropical eagles and the king vulture, which acts as a work guide.

They’re now developing a conservation strategy based on the study, surveillance and protocol development for the protection of the black-and-white hawk-eagle. To achieve a successful result, they work in collaboration with the local guides at the Tamandua Camp Conservation Area. In addition to monitoring the hawk-eagles, members of the camp work on habitat protection, which benefits not just the raptors but also more than 450 species of resident and migratory birds that inhabit the tropical rainforests of southeastern Mexico. The guides also lead ethical bird-watching activities, helping generate revenue that benefits the local community.

Community park ranger Javier Vázquez takes a break near a bonfire at a provisional camp. The sheer expanse of the Lacandon Jungle and the lack of conservation centers here mean rangers and researchers alike have to travel long distances to complete the surveillance and monitoring tasks important for the preservation of the neotropical birds of prey and other important species. Image courtesy of Santiago Gibert Isern.

“The main goal of our strategy is to protect the habitat, and that’s where the ejido sets a preservation area,” Monroy-Ojeda says. “In that space, we promote bird tourism, tourism based on bird observations under a strict protocol that has the well-being of this species as its main goal. The tourists come to observe the birds, but always in areas where they don’t bother the different species or interfere with the nesting process.”

Gibert Isern says that if the nest is in an ejido area and draws visitors as part of the research initiative, the community must benefit too. “The aim is to create awareness and make tourists care for the preservation of the birds too. We must come up with activities that provide an economic benefit on a local level,” he says. “That way, the people who coexist with the eagles are the first ones to care about the preservation of said species and become the guardians of the nests.”

Community instructor Silvano López takes a tour down the Usumacinta River in Chiapas. In 2011 on that same river route, he photographed a harpy eagle, a species that hadn’t been recorded in this region in 20 years. Image courtesy of Santiago Gibert Isern.

The researchers say there’s growing public understanding of the importance of nature, the urgency of environmental issues, and the threats that species face, as well as increasing interest in making changes and environmental commitments for the better.

“The environmental crisis is severe, and I choose to be hopeful,” Monroy-Ojeda says. “I think that we can manage to preserve and restore enough habitat. We work to make that happen because we have hope that the situation can be reversed, and that people can take an interest in preserving the rainforest. Because it’s not only beneficial for the eagles but for all of us because of its water, its oxygen, and all the ecosystem services it provides.

“I think that’s what gives us the push to keep going,” he adds, “to make sure that the future generations will admire these eagles.”