Covering an area of more than 6 million square kilometres, the Amazon Basin dominates northern Brazil and forms a large part of the South American continent. The richness of its biodiversity, and the hostility of its natural environment, mean that even today we can form no clear picture of the Amazon rainforest ecology. Yet even fragmentary glimpses reveal that the Amazon forms an extravagance of nature beyond the wildest imaginings of taxonomists. When biologist T. L. Erwin examined a single species of Amazonian tree, he found 163 unique species of beetle living in its canopy alone (Erwin 1982). Comparing sites seventy kilometres apart, Erwin found only a 1% overlap in the beetle species present (Erwin 1988). Brazil has more species of flowering plants and amphibians than any other country, and ranks in the top four countries on earth for mammals, birds, butterflies and reptiles (Fearnside 1999).