Invasive species in the Everglades are exotic plants and animals that are not native to the area and have aggressively adapted to conditions in wilderness areas in southern Florida. The Everglades are a massive watershed in the southern portion of the U.S. state of Florida that drains overflow from the vast shallow Lake Okeechobee that is in turn fed by the Kissimmee River. In the 20th century, Florida experienced a population surge unparalleled in the U.S., accompanied by rapid urban expansion made possible by draining portions of the Everglades. The widespread building created new habitats and disturbed established plant and animal communities. Many of the new residents or tourists in Florida were responsible for introducing plant species to the area by accident, or deliberately to improve landscaping. Approximately 26 percent of all fish, reptiles, birds, and mammals in South Florida are exotic—more than in any other part of the United States—and the region hosts one of the highest numbers of exotic plant species in the world. (This list is part of a featured topic: Everglades.)