On a humid summer afternoon, Steven Whitfield, a wildlife researcher at Florida International University, leaves the extensive trail system at La Selva Biological Station in Costa Rica and wades deeper into the rainforest. "I'll watch out for snakes for you," he says. I stop in my tracks. "You should probably also look out for them yourself, though," he adds.
We soon meet a red-and-blue poison dart frog chirping loudly on a log. I lean in closer to get a photograph, and the chirping stops. "If you get too close, he'll run away," Whitfield tells me, "but if you stay still for a second, he'll start calling again." Sure enough, the chirping resumes, and another poison dart frog soon hops into view.
Venturing into a swamp within the jungle, we are greeted by a bullfrog poking its head through vegetation, as well as a pair of mating toads. The Costa Rican ...
