Rana catesbeiana

Bullfrogs are the largest frogs in the Chicago Region growing to an average adult size of up to 6 inches (15.2 cm) although some individuals may be larger. They are usually plain, dark green or brownish green and do not have dorsolateral folds. They are semi-aquatic and live in permanent ponds, lakes and rivers. Males are territorial and will fight other males that invade their territory. From May to July their deep "bru-um" call attracts females that lay several thousand eggs in large, gelatinous masses which may measure a yard across (about 1 meter). The eggs hatch into tadpoles which spend that summer and all the following spring in the water. The tadpoles grow up to 6 inches (15.2 cm) in length and metamorphose in the mid to late summer of their second year. Large bullfrog tadpoles can sometimes be seen through the ice in frozen ponds in winter. After transformation, young bullfrogs settle into life around the pond. It takes several years for them to become adult.

Bullfrogs are noted for their voracious, if indiscriminate, appetites. As tadpoles, they eat mostly algae. Adults eat just about anything they can catch and cram in their mouths, including other frogs. Some of the more unusual items observed on their menu include garter snakes, ducklings and even a brown thrasher! Bullfrogs are themselves eaten by herons, snakes and humans. In fact, humans may have spread this species beyond its original range by introducing it to appropriate habitat from which it was previously absent. In parts of Michigan, bullfrogs are becoming rare. The decline has been attributed to overcollecting and a season and bag limit have been enacted in an effort to preserve the giant amphibian.

Species of Frogs and Toads of the Chicago Region

Northern Cricket Frogs
Acris crepitans blanchardi
American Toads
Bufo americanus
Fowler's Toads
Bufo woodhousii fowleri
Tree Frogs
Hyla versicolor complex
Spring Peepers
Pseudacris crucifer
Western Chorus Frogs
Pseudacris triseriata
Rana catesbeiana
Green Frogs
Rana clamitans
Pickeral Frogs
Rana palustris
Northern Leopard Frogs
Rana pipiens
Wood Frogs
Rana sylvatica
Plains Leopard Frogs
Rana blairi
Amphibian links . My homepage

Ellin Beltz ebeltz@ebeltz.net
October 26, 2008

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