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Introduction

The American Bullfrog – North America’s largest frog – is a fascinating species with a remarkable natural history. While SAVE THE FROGS! often highlights bullfrogs because of the challenges they create as invasive species in many parts of the world, it’s equally important to appreciate their unique ecology, biology, and the role they play in their native habitats. From their distinctive croak and impressive size to their complex life cycle, American Bullfrogs are truly extraordinary amphibians worth understanding beyond their reputation. Formerly known as Rana catesbeiana but now more often referred to by scientists as Lithobates catesbeianus, we hope you enjoy this article and share it with your fellow amphibian enthusiasts!

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American Bullfrog photo by Pete Weiler

Size, Appearance, and Diet

Adult American Bullfrogs range from about 3.5 to 8 inches in length. They have green, moist skin and can be easily identified by their prominent eyes, which sit above the level of the skull. Males have yellow throats, while females have white throats. These frogs are carnivorous, consuming crayfish, water beetles, larvae, snails, and a variety of invertebrates and small vertebrates, including mice and even birds. American Bullfrogs are the largest frog species in North America; there are records of individuals weighing over a pound.

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American Bullfrog photo by Thomas Shockey

The Distinctive Bullfrog Call

Bullfrogs are famous for their distinctive croak, often described as sounding like “jug-o-rum.” This call has a unique vibrating tone, accompanied by rapid croaking. Only males produce these calls, forcing air between their lungs and vocal sac. The vocalizations help establish territories and attract mates during the breeding season in spring and summer.

Support amphibian conservation when you purchase one of our bullfrog tote bags!

Reproduction and Role in the Food Chain

When it comes to reproduction, American Bullfrogs lay an impressive number of eggs—anywhere from 12,000 to 20,000 per clutch. These egg masses float on the water’s surface until they hatch. The tadpole stage lasts much longer than that of many other frogs, taking anywhere from one to three years to reach metamorphosis. Because their larvae develop over multiple seasons, bullfrogs need permanent ponds that hold water year-round and are rarely found in ephemeral ponds that dry up each year.

The enormous number of eggs increases the odds that some offspring will survive predation by snapping turtles, herons, raccoons, and humans. This abundance makes bullfrogs an important part of many food webs in their native range.

If you love American Bullfrogs, please organize a Save The Frogs Day event and educate your community about these amazing amphibians!

Introduction to the American West

American Bullfrogs have earned fame among amphibian enthusiasts in the western United States, especially in California, where they frequently win the Calaveras County Frog Jumping Contest—made famous by Mark Twain. In Twain’s day, the contestants were California Red-Legged Frogs (Rana draytonii), now a threatened species.

Unlike California Red-Legged Frogs, the American Bullfrog is not native to the western USA; it is truly an amphibian of the eastern United States and parts of Canada. Bullfrogs were introduced to many regions around the world—often for frog legs or aquaculture—and in these places they can become invasive, threatening native amphibians through competition, predation, and disease transmission. In areas where they are non-native and invasive, wildlife agencies often manage their populations through capture and removal or habitat modifications.

California Red-Legged Frog (Rana draytonii) photo courtesy Jamie Bettaso

Conservation Status and Management

Fortunately, in their native range, American Bullfrogs remain abundant. You can help keep them healthy by protecting wetlands and ponds, avoiding pollution of water sources, and not releasing bullfrogs into areas where they are not native.

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Let’s keep our water bodies clean! Frog art from the 2020 SAVE THE FROGS! Art Contest by Лилия-Мкртчян of Russia.

Other Bullfrog Species

American Bullfrogs should not be confused with African Bullfrogs (Pyxicephalus adspersus) or Indian Bullfrogs (Hoplobatrachus tigerinus), two other large frog species from other parts of the world.