Protecting and enhancing the natural values of Salt Spring Island and its surrounding waters


American Bullfrog

American Bullfrog


Lithobates catesbeianus (formerly Rana catesbeiana) is native to eastern North America and introduced to our area. These frogs breed in permanent ponds and lakes with abundant aquatic vegetation. They are seldom found away from water courses. They are robust and very large, up to about 230 mm in body length. A fold that extends from behind the eye and around the upper portion of the ear drum to the shoulder is diagnostic. Longitudinal folds (dorsolateral folds) along the sides of the body are lacking. The colour of the back and sides ranges from green to greenish brown, often with dark speckles. The abdomen is whitish and often mottled with grey; the undersides of the thighs typically also have grey mottling. The ear drum is large, about the diameter of the eye in females and larger in males. Eggs are laid in warm water from late spring through the summer during a prolonged breeding season. Eggs are small (1.5 mm in diameter) and in loose, floating masses containing up to about 78,000 eggs. The masses are over 30 cm in diameter and larger than Bronze Frog egg masses that are otherwise similar. Tadpoles are greenish brown with numerous black dots and light flecks on the back and sides; the underside is often yellowish. The tail is long with massive trunk musculature. The dorsal fin is low and starts behind the body – tail trunk boundary. Tadpoles resemble Bronze Frog tadpoles but are larger (up to 60 mm in body length, 135 mm in total length), have an arrow-shaped body that is widest at the rear when viewed from above, have spots with clearly defined edges, and often have yellow on the underside. Tadpoles usually overwinter before transforming into froglets and hence require permanent water.

Learn more about Invasive American Bullfrogs at BC Frog Watch.