North American bullfrogs must live in water and are therefore usually found near some source of water, such as a lake, pond, river, or bog. Warm, still, shallow waters are preferred. North American bullfrogs are the largest true frog found in North America, weighing up to 0.5 kg and 203 mm in length. Typical length ranges from 90 to 152 mm. 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.North American bullfrogs prefer warm weather and will hibernate during cold weather. A bullfrog may bury itself in mud and construct a small cave-like structure for the winter. Their hunting style is 'sit and wait.' Bullfrogs can wait for a long time for some type of prey to come by, then, with a flash of the tongue, they grab it and bring it back into their mouths. Bullfrogs are active both during the day and at night; they are most active when the weather is moist and warm. Adult males are very aggressive and defend their territories, which can range from 3 to 25 meters of shoreline, by physically wrestling with others. The call of a male bullfrog has a low frequency and can be heard for over one kilometer. Bullfrogs are predators. They usually eat snakes, worms, insects, crustaceans, frogs, tadpoles, and aquatic eggs of fish, frogs, insects or salamanders. They are cannibalistic and will not hesitate to eat their own kind. There have also been a few cases reported of bullfrogs eating bats.
Source: Lithobates catesbeianus American Bullfrog, Animal Diversity Web, University of Michigan Museum of Zoology