The Remarkable Wildlife of Costa Rica | Deep Into The Wild | BBC Earth

And this is one of the poison dart frogs. This is a walking billboard of a frog. What it's advertising is its own toxicity. These animals contain some pretty potent chemicals in their skins, known as alkaloids. And by walking about on the forest floor, this is what is known as a textbook case of aposematic colouration, which basically says, don't eat me, don't even put me anywhere near your mouth or your eyes, because I could ruin your day. I'm very, very pleased to have found this one. But there is one more I want to get a hold of that lives in the forest around here. And believe me, it's even smaller. Oh, there's one, there's one, there's one. Right, these are so tricky to catch. Right, this is the little frog. This is the strawberry poison dart frog. Got it. Ha ha. You thought I'd done this before, wouldn't you? This is the poison dart frog, known as the strawberry poison dart frog. And you can see why it has that strawberry reference in its name. Just look at that scarlet or orange top to his body. This, again, is another example of warning colouration. This frog also contains those alkaloids in its skin. And I know people who have actually, well, licked their fingers after holding one of these. And they've gone through a very unpleasant sensation of actually having, or feeling like they've actually got a golf ball in their throat. They've had real trouble breathing or swallowing. But very, just so potent, yet so seemingly harmless to look at. An awful lot of frog you can fit on your thumbnail. Ants, leafcutter ants to be precise. Now you might think of these insects as being the sort of things that terrorise and raid your picnic or put the kiposh on amorous activities that occur on the lawn. But not these guys. Sure, they can defend their own if you go poking around in their nest. But these are kind of like the peaceful ants. These are the harvesters and the gatherers. And what we've got here is a foraging trial of ants carrying little bits of leaves back down to their nest. These ants actually have little crafty predators, parasitic flies and wasps, that will quite happily come along and lay their eggs on the ant's head. Now it's thought that the little tiny guard ants that these ants carry on their leaves are kind of the special forces of the ant world, defending against aerial attack from these would-be predators. Deep down underground, the ants are taking these leaves down to a special fungus garden because it's the fungus the ants depend on. Without it, they're stuffed. They simply cannot digest the juices and the plant material they bring down into the nest. Now, this bizarre carnival of ants are actually vitally important to the running of the forest. What they're doing is recycling nutrients, bringing down vegetable matter from the canopy level and putting it back into the ground. And it's thought they're so important in the rainforest, they actually consume 10% of all living plant material. Now, one of the continual frustrations of rainforests is it is a hugely three-dimensional habitat. There's an awful lot more up there than there is down here. And being a two-dimensional ground-based monkey, I'm in trouble. I like these guys. The first sign you get of a group of white-faced capuchin monkeys moving through is ratchets falling to the ground and leaves and occasional twitterings. But they have just moved through. Oh, they're moving through as we speak. There's still some around. Now, one of the surprising things going on here, which I didn't know, it's a brand new thing for me, is that every now and then, through the leaves, you see a bird of prey. I've got no idea what these are, but what they're doing, they seem to be chaperoning the monkeys. Not, as you might expect, to pick off an unwary monkey or two, but actually to pick off the insects. Because, as you might notice, these capuchins are far from ballet dancers up there in the canopy. They lack finesse and they're constantly shaking the branches about and there's bugs and insects and stuff being dislodged. And that is what the birds of prey are picking up on. Yet another example of one of those beautiful relationships between different species here in the rainforest.