By Ron Magill, Zoo Miami communications director
Of all the species found within the rainforests of the Americas, few are as impressive as the harpy eagle. With a wingspan of between 6 and 7 feet and talons the size of grizzly bear claws, it’s one of the largest and most powerful birds of prey on earth.
To put this into perspective, an adult bald eagle generally weighs close to 9 pounds, whereas an adult harpy eagle can weigh more than twice that at nearly 20 pounds. The tarsus of this magnificent bird can be the size of a woman’s wrist, and they can exert over 100 pounds of pressure when snatching their prey.
Learn more about this fascinating bird of prey and the role of the Miami Zoo in its conservation.
Harpy eagle characteristics
Among harpy eagles’ distinguishing features is a majestic crest that they elevate to help create a facial disc, often getting them confused with a large owl. The disc helps direct sound into the ears of the harpy. Though they have exceptional eyesight that’s estimated to be four times as fine as that of a human, the thick canopy in which these birds hunt often obstructs vision and necessitates exceptional hearing to locate prey.
Other distinguishing features are relatively short and stout wings with a long tail. This is an adaptation to facilitate hunting in the dense canopy of the rainforest. As opposed to other eagles that have relatively long wings and short tails for soaring over open areas, such as prairies and bodies of water looking for their prey, the harpy must be able to fly quickly and make sharp twists and turns as it maneuvers through the dense canopy during a hunt.
It’s analogous to the difference between a bomber airplane with long, thin wings that allows it to soar high above its target without any obstructions, and a fighter jet with short, broad wings and special tail to be able to make quick turns to avoid contact during battle.
As juveniles, harpy eagles have plumage ranging in color from off-white to tan and gray. As they mature, dark gray to black bars appear on their wings and tail, creating a stark contrast with their white chest and light gray face. It can take up to five years for a harpy eagle to develop its adult plumage.
Harpy eagles have the slowest reproductive rate of any bird of prey, producing only one offspring every two to three years. Though a female will often lay two eggs, only one chick is raised as it’s incredibly demanding and will be cared for by its parents for up to 18 months.
Their diet consists mainly of arboreal mammals, predominantly monkeys and sloths, but they’ve also been known to take macaws, porcupines, armadillos and kinkajous among others. Because of harpy eagles’ formidable size and strength, they can carry prey weighing up to 15 pounds.
Harpy eagles live in tropical rainforests, some of the most biologically diverse ecosystems in the world. Though tropical rainforests only occupy less than 6% of the earth’s surface, they’re home to approximately half of all the world’s plant and animal species. It’s estimated that there are millions of species of plants, insects, animals and microorganisms yet to be discovered within them.
Where did the name ‘harpy’ come from?
The harpy eagle gets its name from the mythical Greek beasts, “harpies,” creatures with the head of a woman and the body of a massive bird of prey. The myth states that harpies would snatch people and take them to the underworld. Unfortunately, many people took that myth and applied it to the harpy eagle, perpetuating the false narrative that harpy eagles would steal children and eventually livestock.
Because of this, harpy eagles were seen as a threat and shot indiscriminately, which contributed to a declining population. However, it’s habitat destruction that presents the greatest threat to these majestic raptors, as they need great areas of undisturbed forests to thrive.
Zoo Miami’s commitment to harpy eagle conservation
Working with the Wounaan Indigenous tribe of Panama, the Panama Audubon Society and the Peregrine Fund, Zoo Miami participated in an expedition into Panama’s Chagres National Park to visit the active nest of a harpy eagle to gather data and better understand their needs and ecology.
Magill’s expedition to a harpy eagle nest
After hours of hiking through a lush tropical forest, we arrived at the nest tree that was approximately 140 feet tall. Though we could not see the nest at the top of the tree through the lower canopy, the droppings at the base of the tree confirmed its presence and that it was occupied.
We used a modified crossbow attached to a fishing reel to send a line over the top of the tree so that we could set up climbing ropes, with the hope of ascending to the nest to see firsthand what was in it.
As I reached the nest that was approximately 120 feet up in the massive tree, my heart skipped a beat when I saw an approximately 10-week-old harpy eagle chick sitting in the center staring at me with wonder and curiosity! I was joined by Rafael Alvarez, who had ascended before me. He had climbed to several harpy eagle nests previously and was considered one of the world’s experts.
I sat beside the nest which was about 6 feet wide and 2 feet deep. About 20 feet away on a branch of the same tree, the adult female harpy kept a close eye on us. She issued a series of calls that made me nervous, but never showed any signs of aggression. I had read reports of harpy eagles attacking people at nest sites. Rafael calmly explained that, although he was aware of the reports, he had never experienced an attack and reassured me that we weren’t in any danger.
While up there, we collected bones, including skulls and mandibles from several sloths and a skull from a kinkajou, as well as casts that had accumulated in and around the nest. Casts are regurgitated pellets that contain hair, bones, claws and other non-digestible parts of the prey. These items, when identified, would provide a wealth of knowledge about the eagle’s prey species and feeding behaviors.
After closely examining the chick, Rafael set a trap of nylon cords baited with chicken in hopes that we could capture one of the adults so that we could attach a satellite transmitter to it, which would provide us with important data on range and movement.
The following day, we were able to successfully capture the male in the trap and brought him down so that we could collect a series of measurements while also fitting him for a backpack that we would attach the satellite transmitter to. In addition, we attached a leg band with the name “Chagre” inscribed on it in reference to the national park in which he lived. After collecting all the data, Chagre was released and successfully reconnected with the female and the chick at the nest.
Saving the harpy eagle with Jim Fowler
The data we were able to collect on that expedition, combined with all the programs designed to educate the Panamanian people about the harpy eagle, resulted in Zoo Miami leading the effort to build a Harpy Eagle Center at Summit Gardens just outside of Panama City.
A leading consultant in that project was Wild Kingdom’s Jim Fowler, who had served as an inspiration and mentor to me for many years and who was one of the first biologists to publish studies that he did on harpy eagles in Guyana. Jim flew down to Panama with me when we first presented the project. His notoriety and the immense respect people had for him led to the successful completion of the center that he helped design and pick the location for.
Read more about Ron and Jim’s incredible journey to save the harpy eagle.
The ultimate reward for all these efforts happened on April 10, 2002, when Panama passed a law officially declaring the harpy eagle as the national bird of Panama. Today, Panama has an annual festival celebrating the harpy eagle, and it holds a distinguished spot on everything from the national crest to the badges of a variety of Panamanian law enforcement agencies. Most importantly, it’s now federally protected and holds a place of reverence and respect among the Panamanian people who no longer fear the myths of the past.
Since that time, Zoo Miami has exhibited harpy eagles and is presently the only zoo in the United States to successfully reproduce them, with several chicks hatching over the past decade.
The very first chick that hatched was named, “Panama,” and was gifted to the country as a symbol of gratitude and partnership in the conservation of this iconic species. “Panama” continues to live at the Harpy Eagle Center outside of Panama City, where she’s cherished and revered by the many thousands of people who visit the center each year.
For me, that initial experience of sitting in a nest alongside a harpy eagle chick in the wilds of a pristine Panamanian rainforest remains the most amazing wildlife experience of my life. I will never forget having sat in a very special place where normally only eagles dare to fly.
See Ron Magill and Zoo Miami’s harpy eagles on Mutual of Omaha’s Wild Kingdom Protecting the Wild, “The Most Powerful Predator of the Sky.”
