(Bull Frog)
|
(Bull Frog) |
| COMMON NAME: Bull Frog
SCIENTIFIC NAME: Rana catesbeiana STATUS: Federal- No status; States- No status RANKING: Global- Secure; States- Not provided FOREST PRESENT: Dixie, Sawtooth,
REMARKS Not indigenous to Western U.S. May be responsible for decline of native aurans. |
 |
DESCRIPTION: The Bull Frog is the
largest frog in North America. It can reach over 6 inches in length.
Some of the diagnostic characteristics include the absence of dorsolateral
ridges and the presence of a large and conspicuous tympanic membrane (ear
drum). Short folds of skin extend from over the eye to behind the
tympanic membrane, which will be larger than the eye in males and about
the same size as the eye in females. The hind feet are completely
webbed except for the last joint of the largest toe. The dorsal surface
is usually void of any markings but may have spots or dark mottling.
It can range in color from dark olive to pale green. The ventral
surface is usually a light cream to yellow color with dark marbling sometimes
present. Bull Frog tadpoles have a light ventral surface and the
dorsal surface is greenish to yellow with numerous black spots. Bull
Frog larvae winter in the tadpole stage.
LIFE HISTORY: The Bull Frog is
not native to the Western U.S. but was introduced into several localities
in the West where it has been implicated in native anuran declines.
In Region 4, the Bull Frog has became established in various locations
in Utah, Nevada and Idaho. This frog is highly aquatic, and never
strays far from permanent water, whether it be marsh, pond, lake, or reservoir.
It sometimes frequents temporary water bodies long distances from permanent
water. It prefers water with thick aquatic vegetation such as cattails
and can even tolerate brackish water. The Bull Frog is not dependent
on rainfall for breeding. It is nocturnal but calling commonly occurs during
the day as well. The Bull Frog winters at the bottom of water bodies.
BREEDING: Breeding occurs from February through July in permanent water bodies. Eggs are spread out in a large thin sheet over 12 inches in diameter, which is attached to submerged vegetation. Each sheet can contain up to 20,000 pigmented eggs and a sheet can be up to 5 feet wide. Tadpoles may reach lengths of 3 inches or more before metamorphosing. Some larvae may over winter before transforming into frogs.
DIET: Larvae eat organic debris, algae,
plant tissue, suspended matter and small aquatic invertebrates. Adults
consume any animal that can be swallowed, even snakes, bids, fish, crawfish,
and other frogs.
VOICE: Call is a deep pitched "jug-o-rum"
or "Br-wum" bellow. Calls are made during the day and night. It can
be heard up to 1/4 mile away. For recorded CALL
or you can have the CALL WITH SHORT DESCRIPTION.
USDA,
Forest Service
Federal
Building
324
25th Street
Ogden,
Utah 84401