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North American Bullfrog

Scientific Classification

Common Name
North American bullfrog, bullfrog
Genus Species
Rana catesbeiana

Fast Facts

Green to greenish brown; bullfrogs of the southern US are often spotted; irises of gold or brown; both head and body are flattened and broad
Male: The tympanum (eardrum) of the male is larger than the female's
Snout to vent length: 9–15 cm (2.5–6 in.); record 20 cm (8 in.)
Legs length: 17–25 cm (7–10 in.)
Up to 500 g (17.5 oz.)
Voracious appetite; will eat almost anything that moves and that it can swallow - including invertebrates and small vertebrates such as mammals, birds, reptiles, fish, and even turtles and other frogs
Hatch in four days or less
Clutch Size
20,000 eggs produced by a single large female
Sexual Maturity
2–4 years
Life Span
Average 4–5 years
Nova Scotia to Central Florida, west to Wisconsin and the Rockies; introduced to British Columbia and California
Vegetation along edge of large, slow moving bodies of freshwater
Global: No data
IUCN: Not listed
CITES: Not listed
USFWS: Not listed

Fun Facts

  1. North American bullfrogs are capable of leaping 1 to 2 m (3 to 6 ft).
  2. North American bullfrogs are territorial and protect their territories by calls, displays, chases, jump attacks, and even wrestling. Females are attracted to males with territories that provide the most food.
  3. A female North American bullfrog can lay up to 25,000 small eggs that are held together at the surface of the water. 
  4. Hearing is one of the most important senses to a frog. Male North American bullfrogs chorus at breeding ponds; females also give aggressive and reciprocation calls.
  5. North American bullfrogs have teeth in the roof of their mouth and a muscular tongue capable of flipping prey into their mouth.
  6. North American bullfrogs may remain at the tadpole stage for up to 2 years. A longer tadpole stage means a larger frog after metamorphosis, which usually means a better chance of survival. 
  7. North American bullfrogs close their nostrils and continue to absorb oxygen through their skin while under water. 
  8. In general, frogs have smooth skin while toads have textured skin.

Ecology and Conservation

Where North American bullfrogs occur naturally, they are common and help keep populations of insects in check. But they have been introduced into areas of the western United States where, because of their appetite, they are capable of reducing or destroying local populations of native species. Their populations can increase to become out of balance with the species native to those habitats because often they have no natural predators and their skin secretions make them unpalatable to many animals. Bullfrogs, like all amphibians, have porous skin and respond quickly to changes in the environment. The health of their populations can be an indicator of the health of the environment.


Beringer and Johnson. 1995. Herpetological Review. 26(2):98.

Conant and Collins. Reptiles and Amphibians of Eastern and central North America. Boston: Houghton Mifflin Co., 1991.

Dickerson, Mary. The Frog Book. New York: Dover Pub. Inc., 1969.

Duellman and Trueb. Biology of the Amphibians. Baltimore: Johns Hopkins Univ. Press, 1986.

Stebins and Cohen. A Natural History of Amphibians. 1995. Princeton University Press, Princeton, New Jersey