American bullfrog

Rana castesbeiana

Species Information
Exhibit Name and Location Maryland Mountains to the Sea, Allegheny Stream – Main Building, Level 2
Description of Animal Bullfrogs vary in color from brownish to shades of green, often with spots or blotches of a darker color on the back. The belly color ranges from white to yellow, and in some individuals is marked with black spots or a vein-like pattern. The hind feet are fully webbed. Breeding males emit a deep bass jug-a-rum call that can be heard over a distance of more than half a mile (more than one km). During the long spring and summer breeding season, males aggressively defend a territory, wrestling fiercely with rival males and attempting to mate with as many females as possible. Thousands of eggs are laid during the summer. Tadpoles over-winter and slowly transform into frogs over the next 1 to 3 years, depending on food availability and water temperature.
Aquarist's Note North American bullfrogs prefer warm temperatures and hibernate during cold weather. A bullfrog may bury itself in mud and construct a small cave-like structure for protection during the winter. Because temperatures are always summer-like in the Aquarium’s Allegheny Stream exhibit, the bullfrogs remain active year-round.
Diet Bullfrogs eat any animal they can capture and swallow, including worms, insects, crustaceans, other frogs, snakes, and even small mammals and birds.
Size This is the largest North American frog, weighing up to 1 pound (0.5 kg) and measuring up to 8 inches (20 cm) in length.
Range The American bullfrog’s natural range extends from Nova Scotia to central Florida, from the Atlantic coast to Wisconsin, and across the Great Plains to the Rockies. The species has been introduced as far west as California and Mexico. Warm, still, shallow water is preferred, such as around the edges of lakes and ponds, and sluggish portions of streams and rivers.
Population Status Bullfrogs are abundant in their native habitat and play an important role in insect control. In places like California, where bullfrogs have been introduced by humans but do not occur naturally, bullfrog populations are sky-rocketing. A lack of natural predators is one reason as are the bullfrog's higher tolerance for warmer water temperatures, a longer breeding season, and higher rates of tadpole survivorship than in other species of frogs. As a result, bullfrogs are driving some native species of frogs towards extinction through predation on both adults and tadpoles.
Predators The primary predators of bullfrogs are fish, although a variety of birds, mammals, snakes, crustaceans, and insects prey on these frogs and their tadpoles. Humans hunt these frogs for their meat (frog legs). Bullfrogs also prey upon each other.