Miguel Ángel Díaz walks slowly so his footfall on dry leaves doesn’t drive away what he's trying to find in this dense forest of seeded breadnut and sapodilla trees. Coming to a small wetland, a sign warns: Beware of the crocodile.
Díaz, a tourist guide, shines a laser pointer at a woodpecker and a toucan, and then moves it over to the blue tail of a Yucatecan jay. He learned years ago to decipher the sounds of the Calakmul jungle in Mexico's southern Yucatan.
