Commercial Hunting May Be Largest Threat To Tropical Forests

Many of the birds and mammals found in tropical ecosystems are frugivores, animals that disperse seeds rather than eat and kill them. These same animals are hunted at unsustainable rates virtually throughout the tropics. Researchers Richard Corlett, and Carlos Peres and Erwin Palacios review the consequences this has on tropical Asia and the Amazon, respectively, and consider the pervasive consequences for plants.

In tropical Asia, commercial hunting for large-scale regional trade in wild animals has replaced traditional subsistence hunting. Most species are being hunted illegally at unsustainable levels and enforcement is weak in many areas. Reductions in the current rates of deforestation and logging will not be enough to save many of the region's animals from extinction. Ending the trade in wild animals and their parts should be the number one conservation priority in tropical Asia.

Using more than 100 forest sites scattered across the Amazon, the authors show that most large game birds and mammals have been severely reduced to a small fraction of their original population densities, often just 1–5 percent of the densities of the same species in similar protected forests.

Seed dispersal depends entirely on vertebrates for plant species with large seeds encased in fleshy fruits. Thus, hunting invariably alters relative seed dispersal distances among different plant species. Hunting is already changing plant species composition of tropical forests worldwide. As the composition of plant species changes, they may not provide the fruits and seeds necessary to sustain populations of frugivorous and granivorous vertebrates.