The American bullfrog, Lithobates catesbeianus, is a large amphibian known for its size and distinctive call. This species inhabits diverse environments. This article explores the bullfrog’s natural geographical range, preferred aquatic settings, and current global distribution.
Original Home
The American bullfrog is native to eastern North America, with its historical range spanning a vast area. This includes the eastern Canadian Maritime Provinces, extending southward to central Florida. Westward, its natural distribution reaches Wisconsin and stretches across the Great Plains to the Rocky Mountains, encompassing nearly every U.S. state east of the Mississippi River. The species is largely absent only from North Dakota within its native continental range.
Preferred Living Environments
American bullfrogs prefer specific aquatic environments. They thrive in large, permanent freshwater bodies that are either still or slow-moving, including swamps, ponds, lakes, marshes, and sluggish sections of streams and rivers. Dense emergent and submerged vegetation provides important cover and ambush opportunities. Man-made habitats like canals, ditches, culverts, and artificial pools can also support bullfrog populations.
These amphibians are drawn to warm, stagnant waters, which support their growth and reproduction. While they prefer these conditions, bullfrogs tolerate colder temperatures. During winter, they hibernate by burying themselves in mud or debris at the bottom of water bodies. This adaptability contributes to their success in diverse aquatic settings.
Where They Live Now
Beyond their native range, American bullfrogs have established populations globally, largely due to human activity. They are considered an invasive species in regions like the western United States, including states like Arizona, California, and Hawaii. Their global presence extends to Europe, Asia, South America, the Caribbean, and some Pacific islands.
The spread of American bullfrogs has occurred through several pathways. Intentional introductions for food sources, particularly frog legs, and their role in the pet trade were primary reasons for their initial dispersal. Accidental escapes from aquaculture operations, research facilities, or releases by pet owners have also contributed to their establishment in new environments.
Once introduced, these frogs can have substantial ecological impacts on local ecosystems. Their voracious appetites mean they prey on a wide array of native species, including other amphibians, fish, small mammals, birds, reptiles, and insects. This predation, along with competition for resources and habitat, can lead to declines in native populations. Bullfrogs can also act as carriers for pathogens like chytrid fungus and ranaviruses, which are detrimental to amphibian health worldwide.