Frogs and toads hop, swim, crawl and climb across all continents except Antarctica. Their variety and diversity increases as you move from the colder regions towards the equator. It is the warm humid tropical forest realms that have the greatest number of species. Here, in this moist and near constant temperature, species have evolved and specialized over thousands of years. Frogs fill a variety of niches, nooks and crannies, from typical pond and streams, the forest leaf litter, to the canopy.
Costa Rica lies squarely in the tropics, at a crossroads connecting North and South America. This “rich coast” country, is bordered to the east by the warm Caribbean, and the Atlantic Ocean, and to the west by the Pacific Ocean. In between these coasts, lie lowland jungles, mountain forest draped in mosses, alpine tundra, and dry forest–and all adorned with anurans (frogs and toads that is).
Costa Rica hosts 133 species of frogs and toads placed into 8 families. Frogs and toads together form the Order Anura. This is where the term anurans comes from, just another way of saying those amphibians without tails, the “frogs and toads”. The Costa Rican Anurans are a very diverse lot, including dazzlingly gaudy poison dart frogs, and nearly invisibly camouflaged eleutherodactylid litter frogs. Their numbers include the pinky-nail sized froglets, to the fist-sized Smoky Jungle Frog, and behemoth (larger than fist-sized) Marine Toad,. There are short legged ground dwellers, strong-legged pond hoppers, and suction-cupped equipped long-limbed leaf-climbers, all finding food, trying not to be food, and seeing that enough of their frog eggs make it to adult frogs, to survive in a dynamic world.
Peeping, croaking, barking, whistling, rattling, and trilling are a few of the descriptions of frogs calling. Why do frogs call? The quick answer is to attract a mate, and to defend a territory (at least that’s why birds do). Many frogs call infrequently or not at all outside of the breeding season. In an evergreen rainforest environment, breeding occurs when sufficient rain has filled temporary breeding ponds and pools. Such temporary breeding areas will at times explode into a cacophony of several species of frogs all calling and competing for mates. This in turn attract still more frogs to the chorus, as well as frog predators.
The fact that so many frogs are nocturnal–that they operate under the cover of darkness, and that their predominant colorings are greens, browns, tans, and banded or blotched with darker tones, just yells or rather whispers “cryptic, camouflage and stealth”. Yet when it is the breeding season–they grab a megaphone, and turn it up to max and yell, “Hey, Hey, Over Here”, and yell they do with all of of their might, over and over again. OK, Megaphone–no, but an amplifying device called a vocal sac yes.. We’ve all seen the images of the frog with the inflated vocal sac under the chin. The male frogs inflate this sac, and then pushes air through vocal slits in the throat, causing vibrations. These vibrations then resonate in this pressurized air-filled sac or membrane. The point is, that frogs that often act more like army men on a mission than show-off poison-dart frogs, are now making a lot of noise, and in doing so they are putting themselves at great risk. They do this for the survival of their genes, and their species. Apparently, there’s no frog future without pond side peril in the form of pursuing predators in the present. So they squeak, chur, chip chirp and growl for all they are worth. And to a sound recordist, their calls and utterances, place them amongst the most worthy.