Native to the eastern and southern regions of North America, the American bullfrog (Lithobates catesbeianus) has been spreading west across the United States and Canada.
More recently, it's been invading northern states such as Montana. According to biologists, bullfrogs began their leap around the world in 1898, when they were imported to satiate a consumer appetite for frog legs. Similar importations spread the croakers to Asia, Europe, and South America. Bullfrogs loud, deep "jug o'rum" call can be heard from a considerable distance.
American Bullfrogs are voracious feeders, eating anything smaller than themselves, including ducklings, fish, mice, frogs, and small turtles. They have been implicated in extirpations of native frogs and turtles, and declines in waterfowl production. Their lack of predators, prolific nature (one female can lay 20,000 eggs/year), and incentive to relocate make bullfrogs a difficult invasive species to control.
State and federal officials in Montana and several other western states are working to contain and control bullfrog populations.