Amphibians include bullfrogs, green frogs, leopard frogs, spring peepers, wood frogs, and others. Animals can also eat each other; the bullfrog eats crayfish and crayfish eat young bullfrogs. Species occurring on the refuge include bullfrogs and lowland leopard frogs. Adult arroyo toads are also vulnerable to predators such as American Bullfrogs and garter snakes. American bullfrogs are the largest frogs native to Louisiana. Woodhouse toads and non-native bullfrogs are common around the Rio Grande. Amphibians present include American bullfrogs, red-backed salamanders, and spring peepers. Bullfrogs and snapping turtles eat many ducklings. Crayfish and bullfrogs are also found. The waterholes are also home to bullfrogs, chameleons, dung beetles, killifish, and terrapins. As the group played at night, Denny became aware of bullfrogs croaking. Venomous and non-venomous snakes, bullfrogs, and opossums have also been reported to hunt them. In particular, the watercourse includes waterfowl, turtles, bullfrogs, fish, and crustacean species. Male bullfrogs aggregate into groups called choruses. The gular is dichromatic in bullfrogs, with dominant and fitter males displaying yellow gulars.