TIKAL, Guatemala -- Early morning, and thin mist licks around the feet of Tikal's towering Mayan temples. It is that haunted time, not quite light, not quite dark, when one feels that the odds of seeing a jaguar padding golden-eyed through the ruins are at their highest.

In Tikal there is one bat species that eats nothing but other bat species, but as the day strengthens the bats withdraw, and it is time for the birds. Some 285 species of birds have been recorded here. The dawn chorus is all but deafening.

Augmenting the shrieking flocks of low-flying parrots and toucans are Tikal's howler monkeys, whose rumbling, dragonlike roars can be heard up to 7 km distant.