North American bullfrogs are the largest true frog found in North America, weighing up to 1 pound and 8 inches in length. Typical length ranges from 3.5 to 6 inches. Their color varies from brownish to shades of green, often with spots or blotches of a darker color about the back. The hind feet are fully webbed. The sex of an adult bullfrog can be easily determined by examining the size of the tympanum (the external ear of the frog) relative to that of the eye. The tympanum is a round circle located on the side of the head near the eye, and in males, it is much larger than the eye. In females, the tympanum is as large or smaller than the eye. Also, during the breeding season, the throat of the male bullfrog is yellow, whereas the female’s is white.