If you were to hold a contest about which animal in Costa Rica is the most colorful, there would be many contestants. The resplendent quetzal, for instance. Our numerous species of toucans and parrots. Our gorgeous butterflies. And our colorful frogs — especially the red-eyed tree frog.
Red-Eyed Tree Frogs Are Beautiful
And it’s not just because of those fire-engine-red eyes. These brilliant green frogs are decked out in bright blue-purple stripes on a bright yellow background, not to be outdone by bright orange feet. But even with all that flashy color, these little guys can hide in plain sight. Easily. It helps, of course, that they are largely arboreal (living in trees.)
While they are mainly insectivores, preferring to eat moths and crickets, red-eyed tree frogs (Agalychnis callidryus) are not above snacking on other smaller frogs. They excel in hiding in plain sight simply by closing their eyes and hunkering down on a branch or leaf. Then they just tuck their legs under themselves and suddenly it’s “no one’s here. Just us leaves.”
This is a useful trick since these cuties are delectable to alligators, bats, owls, and other birds. And tarantulas (which come in small, medium, and Winnebago in Costa Rica.)
If a predator discovers their clever gambit, those bright red eyes pop open and the frog jumps away flashing a dazzling display of colors, Mental Floss reports. Some scientists think this may work to startle predators, but others believe this makes it easier to escape.
“If you startle a white-tailed deer, the first thing it does is flip up its bright white [tail] and you see that, but as soon as it stops running, the tail drops back down and it blends in with the surrounding environment,” said Don Boyer, curator of herpetology at the Bronx Zoo. “As a predator, you’re looking for that bright blue/yellow contrasting coloration, [but] now that the frog has landed and it looks just like a big green blob on a leaf, you may not detect it.”
Red-eyed tree frogs are also largely nocturnal. They prefer the moist coolness of the night to the relentless heat and humidity of Costa Rica’s climate. It’s also a method for avoiding predators. But even this can be problematic.
That’s because it’s not just adult red-eyed tree frogs that wind up on the menu. Some creatures, such as the cat-eyed snake in the video below, love this creature’s eggs and tadpoles. The snake just swallows them up as if they are the tastiest thing ever. But here again, the frogs have evolved a nifty little trick that often helps them avoid predation from hungry snakes.
Red-eyed tree frogs lay those eggs right above the water
Tadpoles tend to hatch about a week after the eggs are laid, but they can speed things up a bit, should a hungry snake or wasp (yes, some wasps also like the eggs) happen upon them. They can pop out of the eggs after just four or five days and bloop right into the water if needed. Maybe they’ll be safe, or maybe they’ll wind up as food for a hungry spider. A quote from a former creative writing teacher comes to mind here:
“Sometimes Mother Nature can be a real b*tch.”
Well, true. But red-eyed tree frogs have been doing a pretty good job of hanging around, having evolved around 10 million years ago. And a 2008 fossil find shows that frogs have been around for at least 300 million years.
The mating season for these little amphibians lasts from fall to early spring when males begin climbing down from their trees. If you watch the videos, you’ll notice something unique about these colorful critters. Unlike others of their kind, red-eyed tree frogs walk, rather than hop. Males creep slowly down the tree trunk until they are just above water. Once there, they begin calling, and then the females come down from the trees, responding to the calls.
“The breeding aggregations are pretty impressive,” Boyer notes. “I’ve seen breeding aggregations of red-eyed tree frogs in Costa Rica and you can have literally hundreds of frogs around a body of water.”
Male red-eyed tree frogs are much smaller than females
Next thing you know, the whole thing looks like the amphibian version of a brawl. Whatever they may lack in size males make up for in feistiness, wrestling and pinning each other to the damp undergrowth until the best frog wins. Females try to crawl by unnoticed, but the males are definitely on the job and it’s not long before every available female has more of them on her back than she knows what to do with. And they will stay there, patiently waiting for her to pick the best egg-laying spot. Believe it or not, sometimes that takes several days.
Scientists aren’t sure how a female of this species picks a mate but think that size (in many amphibians and more than a few reptiles the male is smaller than the female) and the sound of his call, likely has something to do with it. In a type of mating embrace known as amplexus, the male wraps his arms around her.
As soon as she lays her eggs on the underside of a leaf, the males (sometimes there are still a few hangers-on) release sperm, fertilizing them as they leave her body.
These small frogs are quite remarkable and I count myself lucky to have the chance to see them. We’ve even had them in the garden every now and again. With their splendid colors, they look like living jewels.
And you can watch them in the video below.