2:00 am

The clear winter nights in the jungles of southeastern Mexico are surprisingly cold. This morning, the wet cold wakes me at two in the morning. The darkness is intense, and my eyes take a while to adapt and see -- or guess at -- strange forms. In the little cot where I spent the night, the sounds of the jungle are with me. At the nearby water hole I can hear an animal drinking; it might be a coati. An owl shrieks untiringly. My exhaustion makes me feel like this project -- to continue our study on the ecology and conservation of the jaguar -- began centuries ago rather than last week.

We are in the jungle of the state of Campeche, one of the last refuges for many species of Mexico's tropical flora and fauna. To protect a part of this patrimony of humanity, in 1989 the federal government issued a decree creating the Calakmul Biosphere Reserve covering 723,185 hectares. This land, where 1,600 species of vascular plants and 550 species of vertebrates have been documented, still holds considerable populations of species such as the elegant eagle (Spizaetus ornatus), the tapir (Tapirus bairdii), the white-lipped wild boar (Tayassu pecari), and the jaguar (Panthera onca) which have disappeared in most of the rest of Mexico.