Frog Friday: American Bullfrog

The American Bullfrog (Lithobates catesbeianus) ranges in size from 3.5 to 8 inches, making it the largest native species of frog in North America. This very large frog can be found throughout the Commonwealth. Although they are a commonly found frog, they are far from ordinary and have many interesting features and behaviors.

Size is just one of many ways to identify the American Bullfrog. They range in color from dark green to olive to brown and have a green and yellow throat and a whitish to yellowish belly. The belly is often heavily mottled with small dark blotches. The American Bullfrog’s dorsolateral folds (ridges located on the top/ back of many frog species) are unique in that they do not extend down the length of the body, but rather turn downward just behind the tympanum (the external circular ear located near the frog’s eye). Like other “true” frogs, their back feet are fully webbed.

American Bullfrogs will breed in almost any permanent body of water, including lakes, ponds, and reservoirs. Rarely will they inhabit an ephemeral wetland. They are voracious predators and will eat just about anything that can fit into their mouths including small mammals, birds, fish, snakes and even other frogs! Unfortunately, they have been introduced into many areas outside of their native range where their voracious appetite has had significant impacts on native species.

The males are very territorial and establish their territory through calls, postural displays, and fighting. They breed from May – August, during which time females deposit up to 60,000 eggs in thin floating sheets, which may be up to 3 feet wide! The eggs hatch in approximately 5 days. The tadpoles take up to 2 years to fully develop into a froglet and will usually overwinter in ponds. So next spring, if you see a very large tadpole swimming in a pond, it could very well be a 1 year old American Bullfrog tadpole!

The deep, drawn out calls of the American Bullfrog, “vrrr-rooom” or “jug-a-rum” are classic sounds of summer and are often described as sounding like the distant roaring of a bull. Click on the sound file below to see if you recognize the call of the American Bullfrog.

Call of the American Bullfrog

• October 23, 2015