The Harpy Eagle: Terrifying Apex Predator or Creepy Halloween Costume?

The Muppet Show was a television program for children, but there were certainly a few Muppets that made children uncomfortable. Sweetums was gigantic, ebullient and had little regard for personal space, Uncle Deadly was just plain creepy, but it's possible Sam Eagle was the most forbidding — pompous, ultraconservative and disapproving of nearly everything. He both censured the things he hated and rationalized the things he loved with the slogan "It's the American way!" He was an eagle, after all.

But the suffocatingly patriotic Sam Eagle wasn't a bald eagle (Haliaeetus leucocephalus), the national emblem of the United States. He appears to have been a harpy eagle (Harpia harpyja), the national bird of Panama. But why?

Without seeing into the minds of the Muppets makers, the answer probably has to do with the fact that the harpy eagle is just about the most severe looking — the most judgey looking — bird on the planet. This is to say, the heavy brow, striking black, white and slate gray plumage and crown-like headdress doesn't exactly scream "Approach me! I'm extremely friendly!" Also, go with your gut on this one: They would definitely eye your toddler with interest.

Native to the American tropics, the harpy eagle is the largest eagle in the world, with tarsi (legs) the size of a human's and a claw the size of a grizzly bear's paw. They preside over gigantic territories that can exceed 10,000 acres (4,047 hectares), which they need because their prey is large, too — they eat big animals like sloths and monkeys, macaws and large snakes, picking them out of the tree canopy and carrying them away with ease. Harpy eagles mate for life and a mating pair produces only one chick every three years, feeding the baby for up to 10 monthsafter it leaves the nest at around 6 months of age. They build their nests out of sticks in the tallest, most imposing tree in the rainforest, and they use this roost as a watchtower for spotting all the monkey snacks.

"Most large eagles live in open country like savannas, deserts, oceans and lakes," says Dr. David Anderson, a program director at The Peregrine Fund, a nonprofit dedicated to conserving birds of prey worldwide. "Harpy eagles have short wings and long tails, making them highly maneuverable as they fly through the dense forest canopy to attack prey. Not only can they fly through small openings in the forest, but they have to be massively powerful in order to snatch arboreal mammals out of the trees."

They are also one of the few day-hunting birds that have a facial disc — a structure common in owls, which helps the nocturnal raptors to navigate through trees in the dark and to listen for prey. Harpy eagles need one of these satellite-dish-shaped feather structures on their faces to collect soundwaves and funnel them toward their ears because they spend so much time zooming around in the dim understory of the rainforest, snatching iguanas off branches.

Harpy Eagles Are Listed as 'Near Threatened'

Although it's great to be the most giant and imposing raptor in the forest — apex predators, fearing nothing — it's also proving to be the harpy eagle's downfall. Harpy eagles are listed by the International Union for Conservation of Nature (IUCN) as "Near Threatened," but according to Anderson that classification is misleading:

"Harpy Eagles are definitely under threat," he says. "They are declining in nearly all countries where they are found, and in a few they have been extirpated — they no longer exist in Mexico and El Salvador, for instance. In many places, they are listed nationally as Endangered."

Anderson says there are two main reasons why Harpy eagles are threatened. "Harpy Eagles live in lowland tropical forests, usually below 900 feet (274 meters) elevation, and those forests are under intense pressure as they're rapidly being deforested by growing human populations," he notes.

"Secondly, as more people invade the forests where harpy eagles live, they shoot them out of fear or ignorance. Even though harpy eagles don't eat livestock and pose no threat to humans, it's a sad, common misconception. Because harpy eagles breed for the first time when they are about 6 years old, and they produce only a single young every three years, every time an adult harpy eagle is shot, it is a major loss for the population. They are a species that is not equipped to survive in a rapidly changing world."

Although no one knows exactly how many harpy eagles still exist in the wild, it's estimated that their numbers don't exceed 50,000.

What we do know is they appear to be judging us for our actions.