The American bullfrog is the largest true frog in North America, named for a deep call that sounds like a bellowing bull. It's native to the eastern and central US and southeastern Canada, but people have spread it to many western states, where it's considered invasive.
Appearance
- Appearance
- Adults are usually 3.5–6 in (9–15 cm) long and occasionally reach about 8 in (20 cm). The back is green, olive, or brown, often with small dark spots, and the hind legs have dark bands. Males have a yellow throat and an eardrum much bigger than the eye; in females the eardrum is about eye-sized.
- Voice
- A deep, booming 'jug-o-rum' that can carry half a mile or more. In breeding season, calling is most intense from midnight until just before sunrise.
Look-alikes
Green frogLithobates clamitans
Look along the sides of the back. A green frog has a raised ridge of skin () running down each side; a bullfrog has none, just a fold curving around the eardrum.
Why they get mixed upBoth are big green frogs of permanent ponds and lakes.
Where it lives
- Typical habitats
- Lakes and ponds
- Marshes and swamps
- Slow rivers and large creeks
- Ditches
- Range
- Native across eastern North America, from the Atlantic Coast west to the Great Plains and Texas. Introduced populations live in Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.
- Preferred conditions
- Needs permanent water, so populations can drop in drought years.
- Seasons
In Missouri
Breeding May–Aug
Behavior
- Diet
- A sit-and-wait predator that eats nearly anything it can swallow: insects, crayfish, fish, tadpoles, other frogs, snakes, small rodents, birds, and even bats.
- Activity
- Adults spend winter partly buried in mud at the bottom of ponds.
Life cycle
- Breeding season
- In Missouri, late May through August, peaking in late June.
- Clutch size
- Up to about 20,000 eggs per batch
- Incubation
- Eggs hatch in 3–5 days.
- Larva
- Tadpoles take a few months to turn into froglets in the South and up to 3 years in the North. In Missouri it's usually 11–14 months, including one winter.
- Lifespan
- About 8–10 years in the wild
Conservation
- IUCN Red List
- LCLeast ConcernLow risk of extinction
- Status
- Invasive where it's been introduced, including much of the western US, where it eats and outcompetes native frogs and other wildlife.
- Threats
- Bullfrogs can carry chytrid fungus without getting sick, so they may spread the disease to native frogs.
Culture and stories
- Culture and stories
- It's the state amphibian of Missouri, Ohio, and Oklahoma. In Missouri it's also a game animal with a season and bag limit.
- Its hind legs are eaten as frog legs, and the bullfrog is a common specimen for dissection in biology classes.
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