Fat purple clouds had been gathering all day above Cubará, kicking up a dusty wind and cloaking the forested hills in shadow and mist. When the rain finally came, it came as a torrent, hammering metal roofs, overflowing ditches and transforming roads into rivers. A team of biologists, freshly arrived from Bogotá, could do little besides huddle on a porch in anticipation of their mission: find and document as many bird species as possible.