This is the only toad native to Puerto Rico, and once ranged over the entire lowland portion of the island. But habitat loss brought on by an increasing human population is severely reducing its numbers. Another threat is the marine toad, which was brought from South America in the 1920's to control sugar cane grubs. This large, seven-inch toad preys upon the tadpoles of crested toads and also competes with it for food, habitat, and breeding sites.