Common name: Bullfrog
Scientific names: Rana
Habitat: ponds and streams with deep, slowly moving water
Size: 15 to 25 cm for adults, and up to 15 cm for tadpoles
Description: The Bullfrog is a large green or brownish-green frog with long, strong legs for jumping. This frog usually has dark spots on its back and hind legs. Bullfrog males have a bright yellow throat, and all Bullfrogs have large, exposed eardrums on the sides of their heads.
Fun facts: At night, the Bullfrog makes an impressive sound. It bellows out in a loud, low voice, which sounds like “aarooom.” Many people have been startled by its alarm call, which is a sharp, loud squeak. The frog makes this sound when it jumps from the pond edge into the water. When captured, adult Bullfrogs often relax their bodies and play dead. When released, they quickly jump away.
Life cycle: Female Bullfrogs deposit many thousands of eggs in large masses. The tadpoles require at least six months to transform into frogs. In many areas, they spend the winter as tadpoles and do not transform until their second year.
Ecology: Bullfrogs are native to the eastern United States, but they were introduced into California late in the 1800’s. They are now common in ponds and streams with deep, slowly moving water. While they cannot spend the entire year in temporary wetlands, these frogs sometimes spend the spring in the vernal pools.
The Bullfrog was brought to California as a source of food for people. Since it was introduced, the Bullfrog has hurt California’s wetlands and native species. Bullfrogs eat many animals. Some of them are as big as the Bullfrog itself! Worms, insects, spiders, crayfish, salamanders, other frogs, fish, lizards, snakes, turtles, mice, bats, and birds are all prey for hungry Bullfrogs. Scientists think that the Bullfrog’s large appetite may be responsible for the a decrease in the number of California’s native frogs and fishes. The Bullfrog is food for many animals including snakes, large wading birds, predatory fish, and mammals (including humans).
Conservation: There is no effort to protect Bullfrogs because they are a pest species. It is legal to hunt Bullfrogs in the State of California. People sometimes hunt the frogs for their legs. There are many recipes for cooking frog’s legs. People say they taste like chicken.
Investigate: Which species in the vernal pool grassland could be affected if Bullfrogs found their way into a vernal pool? Remember to consider the species that Bullfrogs eat, as well as the native species that are connected to those species through the food web.