American Bullfrog

Description:

The largest of all North American frogs, this giant can grow to a length of 8 inches (20 centimeters) or more and weigh up to 1.5 pounds (750 grams). Even the tadpoles of this species can reach 6.75 inches (17.2 centimeters) in length. A large frog, light green to dark olive green above, with dark spots and blotches. Juveniles have many small dark spots. Sometimes light green only on the upper jaw. Cream to yellow below with grey marbling on larger individuals. No dorsolateral folds. A short fold extends from the eye over and past the eardrum to the forearm. Conspicuous tympanum. Males have tympanums larger than their eyes and a yellow throat. Tadpoles are greenish yellow with small spots, growing up to 6 in. (15.3 cm). A loud low-pitched two-part drone or bellow, popularly described as "jug-o'rum." These calls are made during the day and at night. Bullfrogs also produce an alarm call, a fast squeak, which is usually made before the frog jumps into the water to escape from danger. A sharp encounter call is also made, and a loud open-mouthed screaming sound is made when a frog is under extreme stress. Bullfrogs and tadpoles are upalatable to many predators. Adults and juveniles are capable of hopping large distances, and when disturbed, they will hop into water and dive down, usually making a loud squeaking sound as they jump. Eats anything it can swallow, including invertebrates, mammals, birds, fish, reptiles, and amphibians including other bullfrogs. Bullfrogs sit and wait for food to come near them, then they lunge after it. It is likely that bullfrogs hunt and eat other frogs after hearing their breeding or distress calls. Tadpoles eat algae, aquatic plant matter, and some invertebrates. Mating and egg laying occurs mostly from May to late August (but in some areas it occurs as early as March and as late as October.) Males are reproductively mature in 1-2 years, females in 2-3 years. Older females are capable of laying two clutches of eggs in a year. Eggs are laid in a sheet of jelly about 2 feet in diameter. The egg mass floats at first, then sinks to underwater vegetation just before hatching. A female may lay as many as 20,000 eggs and lose up to 27 percent of her body weight. Eggs hatch in 3 - 5 days. Tadpoles enter metamorphosis anywhere from a few months in the South to the end of their 2nd or 3rd summer in Michigan. In most of California, transformation probably occurs after the second summer. (This is just a guess based on seeing many large tadpoles in California waters that appear to have lived at least a year.) Tadpoles prefer areas of warm shallow water with dense aquatic vegetation. Transformed froglets are 2 in. (5 cm.) in length.

Habitat:

Inhabits warm, sunny, open, permanent water - lakes, ponds, sloughs, reservoirs, marshes, slow river backwaters, irrigation canals, cattle tanks, and slow creeks. Found in grassland, farmland, prairies, woodland, chaparral, forests, foothills, and desert oases.

Notes:

This specimen was huge!