Mantled Howler Monkey

You will hear a mantled howler long before you see one, and possibly before you are fully awake: the dawn roar of a male carries three kilometers or more through wet forest, produced by a resonating throat bone that turns a ten-kilogram monkey into a public address system. The howl is real estate law, troops announcing position so that rival groups can avoid an actual fight neither can afford. Howlers run the rainforest's low-energy strategy: they eat leaves, which are abundant and nearly worthless, and pay for it by resting up to three quarters of the day, draped over branches like discarded coats. Troops of a dozen or two are a fixture of Costa Rican forest, mangrove and even roadside strips.