The Bullfrog, Rana catesbeiana, is the largest and arguably the most recognizable frog in North America. Bullfrogs typically have green heads and mottled brown bodies. They can be distinguished from smaller Green Frogs, Rana clamitans, by the folds of skin that that start at the eye and wrap around the tympanum.(eardrum, or large circle behind eye) In Green frogs this fold extends down the back. Their large, powerful hind legs make them popular at frog jumping competitions as well as the dinner table. Record jumping frogs have been recorded leaping over 7 feet!
A Bullfrog’s sex can be determined by looking at the size of the tympanum. In female Bullfrogs the tympanum is about the same size as the eye. In the male Bullfrog the tympanum is usually much larger than the eye. Males also have yellow throats during the breeding season. The males will often fight and wrestle to defend prime nest sites, and you can often hear the deep alternating “rum-rum” calls of neighboring males. Females can lay up to 20,000 eggs in a clutch.
Bullfrog tadpoles are large and can take up to 3 years to complete metamorphosis. Because of this, Bullfrogs are usually found in permanent bodies of water, and not in vernal pools etc. Because Bullfrogs eat pretty much anything that fits in their mouths, including other amphibians, birds, mice, and even snakes, their presence can have an impact on what other species are found in an area. Introductions of Bullfrogs into areas outside of their native range can have a devastating impact on local amphibian populations. This has been the case in the western US, where Bullfrogs were introduced (accidentally and on purpose) in the early 1900’s.
Despite their large size and formidable appetites, Bullfrogs too have predators to worry about. Snapping turtles, Water snakes, Raccoons and Humans will prey on Bullfrogs. In captivity Bullfrogs have been known to live over 15 years, but most in the wild won’t make it though their first year.