American Bullfrog
-
Scientific Name
Lithobates catesbeianus - Visit ITIS for full scientific classification.
-
Description
American Bullfrog. © B Kimmel (commons.wikimedia.org)- Large frogs, can grow up to 8 inches in length, and can weigh up to 2.5 pounds.
- Wide heads, thick bodies, long hind legs and webbed feet.
- Large visible eardrums.
- Smooth skin.
- Green to brown color on backs, dark spots, and a cream to yellow colored belly.
- Large tadpoles that can grow up to 6.5 inches in length.
-
Habitat
- Extremely adaptable creatures, found in a wide range of habitats, both natural and man-made.
- Typically found around permanent water, which is necessary for successful reproduction but young frogs and dispersing individuals may be found around temporary water sources.
- Prefers warm temperatures, but can withstand conditions below freezing by burrowing into the sediment.
- Usually found in still, or slow-flowing waters.
-
Invasion Pathways and Distribution
- Initially introduced in some areas for human consumption.
- Can spread by natural dispersal, and through accidental inclusion in fish stock.
- May also spread through escape or release from research facilities, aquariums, or by pet owners.
- They can spread naturally by swimming through rivers and streams, and can be carried by water flow during flood events.
- Native to the eastern U.S., but now widely distributed throughout California.
- See USGS for a map of current U.S. distribution.
-
Life History
- Bullfrog breeding occurs in the warmer months within vegetation beds of permanent water bodies.
- Males are very territorial, and fight over the best egg-laying sites. Eggs are laid in sheets that create rafts on the water surface.
- Tadpoles eat algae, small animals, and small tadpoles of other frog species.
-
Impacts
- Consumes almost anything it comes across including: birds, rodents, snakes, turtles, frogs, crayfish, other invertebrates, etc.
- Tadpoles can eat tadpoles of other frog species.
- Strong ability to consume and outcompete native frogs and other native species.
- Can spread a potentially fatal skin disease (Chytridiomycosis) to native frog species.
-
References and Useful Links
For references by category and links to other useful AIS sites see our Learn More page.
