The problem with these nonnative species is that they
have no "natural predators, competitors, parasites, or pathogens" that control their population. (Sustaining Biodiversity). Poaching and hunting is another cause of wildlife extinction, but it is a very lucrative business so it is popular. Predator control is also causing extinction. "Since 1929 U. S. Fish and Wildlife
Service's vital Wildlife Without Borders Program, whose Critically Endangered Animals Conservation Fund supports several, freshwater turtle and tortoise conservation projects around the world. Knowledge fits to focus and action. That integration is evident as Jim Breheny, the Wildlife Conservation Society's Executive Vice President and Bronx Zoo Director, indicates: 'This has been the mission of the Wildlife Conservation Society from the very beginning, to bring its expertise for the achievement of one conservation goal: saving species from extinction. More than a century ago, WCS led the way to save the American bison from extinction in North America by breeding animals at the Bronx Zoo and sending their offspring to wild places in the west. Now our zoos, zoological health program, and field conservationists plan to do the same for some of the world's most endangered turtles.