Rana catesbeiana

Raca.jpg (6088 bytes)

Key Characteristics:

Adult Characteristics

Tadpole Characteristics

Egg Characteristics

Large tympanum

Eyes inset from
margin of head


Lack dorsolateral ridge

Olive ground color
with black specks

Large sheets
(up to 20,000)

Have a dorsal fold
from eye to shoulder

Dorsal fin doesn't
extend onto body


Large size

      .       .

Males call

    .     .

General Description:
Bullfrogs are the largest anurans occurring in Idaho.  They may reach sizes between 150mm to 200mm (7.9 in.) snout-to-vent length.   They are easy to recognize due to the presence of a fold of skin that extends from the eye, goes around the large tympanumclick here for definition and down to the shoulder.  Bullfrogs lack the dorsolateral folds present on Northern Leopard Frogs.   Bullfrogs vary in color, but generally have a dorsal ground color that is some shade of green with darker spots or blotches.  Their ventral coloration is white to yellowish and may have dark mottling to some degree.  Male Bullfrogs give a deep bass call while defending their territory and attempting to attract females.

Bullfrog tadpoles are equally large (compared to other tadpole species), and may reach lengths of up to 150mm (6 in.).  Their dorsal coloration is generally an olive to yellowish green with numerous black specks.   Their ventral coloration ranges from white to cream.  Their dorsal fin doesn't extend onto the body and their eyes are inset from the margin of their head (unlike the Hylid tadpoles).  Bullfrog tadpoles overwinter and don't metamorphose until late the following summer.

Bullfrog eggs are laid in large sheets, over 300mm (12 in.) in diameter.  The eggs are initially laid on the surface but they sink to the underlying vegetation and debris before hatching.  The small eggs (1.3mm or 1/20 in.) are pigmented and generally hatch in 4 or 5 days.  Even though the eggs themselves are small, large clutches of up to 20,000 eggs may be laid.

Idaho Distribution:
In Idaho the distribution of Bullfrogs is associated with the Snake River Plain in the western portion of the state and in the western part of the panhandle.

Distribution was not modeled for this species.

Since its introduction into the Pacific Northwest, the Bullfrog has become well established in many permanent waters, especially at lower elevations.  These frogs are highly aquatic and are seldom found far from the edge of their water source.   Permanent water sources such as lakes, ponds, sloughs, slow moving rivers and streams  are all utilized by Bullfrogs.

Game species
Global Rank:
State Rank:
SE nonnative species to Idaho

Species description, key characteristics and original work by John Cossel Jr. © 1997
Species ecological information from Groves et al. ©1997.
Original images provided by Charles R. Peterson, Henry J. Fabian and Charlotte C. Corkran,© 1997
Design and Optimization by Ean Harker©1999, 2000.
DAI layout by Stephen Burton, and Mike Legler © 1999.