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Today on Animal Fact Files we’re talking about hoatzins. Along the waterways of the South American Amazon and Orinoco river basins are arboreal birds with a prehistoric veneer. Technically, it’s currently understood that all living birds are the remaining descendants of avian dinosaurs - meaning all birds are dinosaurs - some may just look more “dinosaury” than others. We’ve talked about the dinosaur-like shoebills and cassowaries - but today’s subject even comes with dino claws - at least as a baby.

Hoatzins live in wetlands, swamps, and along forest rivers throughout northern and central South America. They’re mostly active during the day, sticking close to the water’s edge, but on bright moonlit nights they may venture slightly deeper into the woods in search of their unique food which we’ll be discussing later in this video. Generally, these birds don’t travel much, even when they “migrate” during the dry season. If the area they normally live dries up, they may move to a more permanently wet area - though they don’t really travel further than a mile (1.6 kilometers) - so we’re not even sure that counts as a “migration.”

Hoatzins are so unique, scientists aren’t even sure how to classify them - even with DNA. In the past they’ve been said to be closely related to cuckoos, doves, and cranes, but ultimately the verdict’s still out. Because of their enigmatic nature, hoatzins belong to their own order - an order in which they are the sole living species.

One unique hoatzin attribute is their claws - though it’s really more about how they use them and less about them actually having them. Technically, there are other living bird species, such as the Eurasian coots and some turaco species which develop wing claws at some point in their life cycle. So hoatzins aren’t alone in having clawed wings; they are, however, the only birds known to science that use their claws to climb.

Hoatzins aren’t really great at flying. Considering these birds are kind of like small turkeys in terms of size, weighing in at 800 grams (1.8 pounds) in weight and more than two feet (61 centimeters) in length, hoatzins similarly aren’t the best at soaring through the air. They’re more well designed for perching in trees and hopping along tree branches. Even hoatzin babies may not learn to fly for weeks after leaving the nest - this is why they use their claws to climb.

Hoatzins built their nests over water. If a predator such as a toucan, monkey, snake, or hawk comes in to attack a nest, the babies will make a break for the waves. They may not be able to fly, but they can fall and they can swim! Once the danger has passed, the hoatzin chicks will make their way back up the tree using the claws found on approximately what would equate to their first and second fingers. There are usually two babies to a nest and they often have quite a few caretakers.

A breeding pair of hoatzins are generally considered monogamous, though roving males may try to seduce a female if her partner is away. They’ll breed during the wet season and take turns incubating the eggs and feeding the chicks, but they’ll also have some assistance. Their babies from previous years may stick around and help raise their younger siblings. In instances where helping siblings are present, the hoatzin chicks generally leave the nest and begin flying faster!

Though they may look like raptors ready to pounce on an unsuspecting creature, hoatzins are actually vegetarians. Not only that, but they’re almost exclusively folivores - meaning their diet consists mostly of leaves. Sometimes hoatzins will eat flowers and fruits, but most of what they eat are leaves. These leaves are digested in a way that’s similar to a sheep or a cow. The leaves are broken down in the hoatzin’s digestive tract by symbiotic bacteria, and just like the ruminants they mimic, hoatzins are gassy! In fact, the process can be so stinky these birds are often described as smelling like dung!

For more facts on hoatzins, check out the links in the description. Thank you to Lin Stern for today’s request. Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files!