American Bullfrog (Rana catesbeiana)
This very large species of frog is similar in coloration to the Green Frog, but fully mature specimens can have a snout to vent length almost 1.5 inches longer. Bullfrogs are found around large bodies of water and spend most of their time in the shallow water along the shore. Like male Green Frogs, Bullfrogs also have a yellow throat during the reproductive season. To distinguish the two species it is necessary to examine the fold of skin that curves behind the tympanic membrane (the circular patch of skin that covers the ear). In the Green Frog this fold of skin continues as a dorsolateral fold while in the Bullfrog it terminates just behind the ear.
In May the males begin calling to attract mates. Females lay eggs in masses in the shallow water. The eggs develop rapidly and tadpoles emerge in less than a week. They spend two years as tadpoles growing to a length of 3 to 5 inches before they metamorphose into young frogs. Mature tadpoles have well developed hindlimbs with webbed feet. Notice how the shape of the head changes as the tadpole begins to change into a frog. The eyes protrude above the skull and the mouth becomes enlarged. Forelimbs appear and the hindlimbs continue to develop. The color changes from tan to dark green. Eventually the tail will disappear.