Bullfrog (Rana [Lithobates] catesbeiana)

Photos by J.D. Willson unless otherwise noted

Description: The bullfrog is the largest frog in the U.S., ranging in length from 3.5 – 8 in (9 – 20 cm.). Coloration is normally plain green above, or a netlike pattern of gray or brown on a green background. The venter is whitish and often has grey mottling with a yellow wash, which is evident on the throats of adult males. In the southeastern part of the bullfrog’s range, coloration can be a heavy pattern of dark grey, brown, or black above, and thick mottling below. They have no dorsolateral ridges, distinguishing it from the similar green/bronze frog (Rana [Lithobates] clamitans). The bullfrog closely-resembles the pig frog (Rana [L.] grylio), but bullfrogs have a less-pointed snout and less-extensive webbing between the toes (webbing does not reach the end of the toe).

Range and Habitat: Bullfrogs are found throughout the eastern and central U.S. and have been widely-introduced elsewhere. They are found throughout Georgia and South Carolina and may be found in nearly any aquatic habitat. They generally breed in permanent ponds and have a higher tolerance for fish than other amphibians in our region.

Habits: Although generally highly aquatic, Bullfrogs may be found moving about on land at night or in wet weather. They are often seen at the edge of ponds and lakes amidst emergent vegetation. Bullfrogs are voracious predators and will attach nearly anything that they can fit in their mouth including insects, other frogs, salamanders, small snakes and turtles, and even small birds. Breeding occurs in late spring and summer. Rather than forming large breeding choruses, male bullfrogs call sporadically throughout the breeding season. Each female lays 15,000 – 20,000 eggs each summer. Tadpoles attain very large sizes and take 1 – 3 years to metamorphose.

Call: The call of the Bullfrog is the familiar “Jug-o-rum,” that is often heard on summer evenings. When captured by a predator Bullfrogs may emit a loud screech that presumably attracts attention to the predator.

Conservation Status: The bullfrog has no serious threats, except for wetland development, and is abundant where it is found. The bullfrog has been introduced in much of the western U. S. and is considered a pest species where it is introduced because of its voracious appetite, which has lead to the local extirpation of some other amphibians and reptiles. In some areas this species is harvested for its legs.

Pertinent Reference:
Boone, M .D, E. E. Little and R. D. Semilitsch. 2004. Overwintered bullfrog tadpoles negatively affect salamanders and anurans in native amphibian communities. Copeia 3:683-690.

Account Author: Matt Slafkosky, University of Georgia – edited by J.D. Willson