American Bullfrog: River Wildlife Guide

American Bullfrog at a glance

The American bullfrog is North America's largest native frog, known for its deep, resonant breeding call. It is native to much of eastern and central North America, including the Mississippi River basin. Introduced populations are established in the Columbia River basin, where the species is not native. Its large size, broad diet, and association with permanent freshwater help it thrive in many altered landscapes. Although globally widespread and not considered threatened, it can harm native wildlife where introduced.

Behaviour & reproduction

Size: Adults usually measure 9–15 cm (3.5–6 in) from snout to vent, with large individuals reaching about 20 cm (8 in).
Weight: Adults commonly weigh 100–500 g (3.5–18 oz), with exceptionally large individuals exceeding this range.
Lifespan: Typically 7–9 years in the wild; captive individuals can live up to about 16 years.
Status: Least Concern (IUCN).

American bullfrogs spend much of their time in or beside water, often resting with only their eyes and nostrils above the surface. They are frequently active at dusk and at night, but may also bask and feed during daylight. When startled, they typically leap into the water and hide beneath the surface or among aquatic plants. During the breeding season, males call to attract females and defend territories against other males. Territorial encounters can involve vocal exchanges, displays, and wrestling. Females lay broad, floating sheets of eggs, and neither parent provides care after spawning. In cold weather, bullfrogs become dormant underwater, usually resting on the bottom or sheltering among submerged material.

Top wildlife locations

Columbia

Riparian and refuge habitats along the Columbia in the Pacific Northwest. Wildlife access depends on the river reach and the actual shore program.

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Mississippi

These species are documented along the Upper Mississippi corridor. An upper-river record does not promise presence on a Lower Mississippi sailing.

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Destinations describe the species' habitat, not guaranteed cruise stops. Some animals require an optional inland excursion or are found in restricted reserves.

Fun facts about the American Bullfrog

Its common name refers to the male's low, bull-like call.
Tadpoles may take two years or longer to transform in cooler climates.
Bullfrogs use their eyes to help push food down while swallowing.
The visible circular disc behind each eye is an eardrum, called a tympanum.

Best time to see the American Bullfrog

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

American Bullfrog: season matrix by destination

Travel and observation windows vary by region. Highlighted months are an orientation for planning, not confirmed sightings or a guarantee of access.

Columbia

No river-specific wildlife calendar is confirmed. Check the actual river reach, local conditions and excursion access with your operator.

JanFebMarAprMayJunJulAugSepOctNovDec

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Mississippi

No river-specific wildlife calendar is confirmed. Check the actual river reach, local conditions and excursion access with your operator.

JanFebMarAprMayJunJulAugSepOctNovDec

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Where the American Bullfrog lives

This species favors permanent freshwater, including ponds, lakes, marshes, reservoirs, and slow-moving river margins. Along the Mississippi, suitable habitat includes backwaters, oxbows, and vegetated shorelines away from strong currents. In the Columbia basin, introduced bullfrogs occupy ponds, wetlands, sloughs, and other sheltered waters. Warm, shallow edges provide feeding and breeding areas, while deeper water offers refuge. Permanent water is especially important where tadpoles need more than one season to complete development.

What the American Bullfrog eats

Adult bullfrogs are opportunistic predators that usually wait for prey before lunging to capture it. They eat insects, spiders, crayfish, and other invertebrates, as well as small fish, frogs, and other vertebrates they can swallow. Cannibalism occurs, and unusually large individuals may take small snakes, birds, or mammals. Tadpoles feed mainly on algae, plant material, and organic debris, while also consuming some animal matter.

Species at a glance

Common name: American Bullfrog
Scientific name: Lithobates catesbeianus
Animal group: Amphibians
Size: Adults usually measure 9–15 cm (3.5–6 in) from snout to vent, with large individuals reaching about 20 cm (8 in).
Weight: Adults commonly weigh 100–500 g (3.5–18 oz), with exceptionally large individuals exceeding this range.
Lifespan: Typically 7–9 years in the wild; captive individuals can live up to about 16 years.
Status: Least Concern (IUCN).
Identification: Look for a large, robust frog with green, olive, or brown upperparts, sometimes marked with darker mottling, and a pale underside. A conspicuous round eardrum sits behind each eye, typically larger than the eye in males and roughly eye-sized in females. Unlike many similar frogs, bullfrogs lack long raised folds running down the sides of the back; instead, a fold curves around each eardrum. Breeding males often have a yellow throat and give a deep, repeated call commonly rendered as 'jug-o-rum.'

American Bullfrog: frequently asked questions

Where can I see the American Bullfrog?

Columbia, Mississippi. From a river ship, scan sheltered, vegetated shorelines and backwaters with binoculars, since individual frogs can be difficult to distinguish at a distance. On excursions, pause quietly near permitted wetland viewpoints and listen for the low breeding calls of males. Stay on established routes, keep clear of fragile banks, and never handle, feed, or move frogs, tadpoles, or eggs. Clean mud and plant material from footwear and equipment between wetland visits to help reduce the spread of invasive organisms and amphibian pathogens.

When is the best time to see the American Bullfrog?

Ask about the specific river reach and shore excursion. No local monthly sighting calendar is confirmed.

How big does the American Bullfrog get?

Adults usually measure 9–15 cm (3.5–6 in) from snout to vent, with large individuals reaching about 20 cm (8 in).. Adult weight: Adults commonly weigh 100–500 g (3.5–18 oz), with exceptionally large individuals exceeding this range.. Size varies with age, sex and population.

How should I behave around the American Bullfrog?

From a river ship, scan sheltered, vegetated shorelines and backwaters with binoculars, since individual frogs can be difficult to distinguish at a distance. On excursions, pause quietly near permitted wetland viewpoints and listen for the low breeding calls of males. Stay on established routes, keep clear of fragile banks, and never handle, feed, or move frogs, tadpoles, or eggs. Clean mud and plant material from footwear and equipment between wetland visits to help reduce the spread of invasive organisms and amphibian pathogens.

What does the American Bullfrog eat?

Are wildlife sightings guaranteed on a river cruise?

No. Animals move freely and routes, weather, access restrictions and local conditions influence every outing. Confirm the actual itinerary and shore program before booking.