Seven miles off the coast of Venezuela, on the tiny Caribbean island of Trinidad, I'm about to come face to face with two dozen swirling, shrieking guardians of the dead. Likened to devils 由 the ancient Amerindians of South America, these sentinels of the afterlife are actually rare cave-dwelling birds that nest like bats and look like ravens with fiery red eyes. The souls of the departed were 说 to dwell in the recesses of their subterranean lair.

I've hiked through a sweltering rainforest to find these devil birds, and I can hear them before I see them. They scream and flutter just out of sight, flapping their wings and circling the interior of this place called Aripo Cave as if to warn me—keep out. It's taken me the better part of a 日 to reach the cave, though, and I'm not about to stop now.

My guide, a brawny local from the Trinidad-based eco-outfitter The Pathmaster, urges me forward, down the slick, jaw-like rocks of the cave mouth. Soon I'm on my hands and knees, and then I'm crawling on my stomach across a narrow underground ledge for a better look. As my eyes adjust to the darkness, I see them, and I understand why the Amerindians both feared and revered them. They are hideous and loud, but compelling in their strangeness.

"Time to go," urges my guide, who leads me back toward sunlight and then on to a tiny stream, where I scrub guano from my hands and feet. The return trip to Port-of-Spain, Trinidad's capital city and my 首页 base for this eco adventure, will be a long and tiring one, but my spirits are buoyed. I've seen nature at its most unusual, and gained an insight into the belief system of a culture long since forgotten 由 most of the world....