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Resource Cards

In the Mid-Columbia, you'll find bullfrogs in ponds, back-waters, and irrigation canals.

Bullfrogs are amphibians. They live both on land and in water. They are nocturnal animals capable of jumping nine times their length. Mid-Columbia residents who live near wetland areas may hear the loud booming call of the male bullfrog at dusk and during summer nights.

What do Bullfrogs look like?
Bullfrogs are the largest frogs in North America. Their bodies are usually a dull green color, but may be brownish, and adults range in size from 3.5 to 6 inches long. Their external eardrum (tympaniomembrane) is large. The male and female are distinguished by the size of the eardrum. The female's eardrum is approximately the size of the eye, while the male's is larger than the eye. A bullfrog's hind feet are fully webbed except for the last joint of the longest toe.

Where do Bullfrogs live?
Bullfrogs range naturally from the eastern to central U.S., north to Nova Scotia, and south to Mexico. The species was introduced to the Pacific Northwest in the late 1920s or early 1930s as a food source because they have big, meaty legs, which are said to be low in calories and fat and highly nutritious. In the last 70 years, the bullfrog has greatly expanded its range. It is larger than native frogs and, in some areas, may have displaced them.

In the Mid-Columbia Basin, bullfrogs prefer permanent stagnant water bodies such as ponds, riverine backwaters, and irrigation canals. They are often found at water's edge and, when frightened, are just as likely to head for cover in the grasses as in the water. They are aggressive when defending their territory. Although not abundant locally, you can find bullfrogs in the willows at the Ringold irrigation return and in the Yakima River. Scientists also have observed bullfrogs sitting on such unlikely places as Russian thistle mats washed into still water in the Columbia River at Leslie Groves Park.

What do Bullfrogs eat?
Bullfrogs eat insects, crayfish, other frogs, minnows, and even small snakes and young birds. Because they are such voracious eaters, they can upset the natural ecology of a site when introduced. Female bullfrogs attach their eggs to underwater vegetation. The young tadpoles can take from 1 to 3 years to mature, longer in cooler climates.

"Science is constructed of facts as a house is of stones. But a collection of facts is no more a science than a heap of stones is a house." Henri Poincare

Keep in mind this fact sheet is intended to be used only as background information to support your effort to encourage inquiry-based science, which parallels the way scientists uncover knowledge and solve problems.

Conduct a research project on the life cycle of frogs. What are the stages in the lifecycle of a frog? Did you know that frogs go through something called metamorphosis? To learn about metamorphosis, conduct your own research in a classroom, at home, or as a science club project. Remember to take the time to explore the great outdoors and look for frogs as well. Before starting this experiment, read a book on frogs so you understand what is involved in raising these fascinating animals.

To begin the experiment you will need frog eggs. Most living specimens may be either purchased locally at pet shops or through school biological supply companies. If you collect frog eggs in the wild, take only a small amount and leave the rest. Once you have your eggs place them in a large container or aquarium. Add pond plants. NOTE: If you plan to capture tadpoles, make sure you are not capturing a species that is on the concerned, threatened or endangered species list. Check with your state or local wildlife office to find out what species you can collect. Also if you raise an exotic frog, do not release it into the wild. Check with the supplier to find out what to do with your frog(s) once your experiment is completed.

Observe the developing frog eggs daily. The tadpoles hatch from frog eggs in a week to 10 days. Once you have tadpoles make sure to have pond plants for them to feed on; if you cannot get pond plants you can feed them small pieces of cooked spinach or lettuce. The transformation from tadpole to frog is fascinating to observe. Keep a journal or other record-keeping device. Include life cycle drawings, descriptions, and measurements of the frog at different times in its lifecycle. Be creative in how you express what you have observed, researched and learned.

Try some of these activities:

• Go to the library and check out books on frogs: Do all frogs take the same amount of time to go from egg to adult frog? Create a chart of the different frogs and their lifecycles. Why do you think there is so much variety?
• Pretend you are a frog. Write your life story, making certain you mention your life cycle somewhere in your tale.
• Write a letter to an organization that is interested in or currently conducting research on reptiles and amphibians. Ask for information about the frogs or other reptiles and amphibians. Find out information on life cycles or ask for suggestions on how you can help.
• Write poems, create a play, or organize a debate about the impact of bullfrogs or other introduced plant and animal species. (Adapted from AskERIC Lesson Plant—Animal Life Cycles.)

Learn important frog facts from the Oregon Coast Aquarium web site: The Case of the Disappearing Frogs."She walked into my office late one day and brought trouble with her. The first thing I noticed were her legs. They were long. Come to think of it they were green, too, with funny little webbed feet. She looked at me with those big bulging eyes and I knew she needed help. I took her arm and hopped her over to a chair. Her skin was moist. She told me her offspring were missing...all three thousand of them." Thus begins the story of the disappearing frogs. This educational site tells the story of the victims, the crime, the suspects, and possible solutions.

1. Amphibians and Reptiles of the Pacific Northwest, 1983. R. A. Nussbaum and R. M. Storm, University Press of Idaho, Moscow, Idaho.
2. Amphibians and Reptiles of Western North America, 1954. Rober C. Stebbins, McGraw-Hill Book Company, New York.
3. Amphibians of Washington and Oregon, 1993. William Leonard, Seattle Audubon Society, Seattle, Washington.
4. Biology of Amphibians, 1994. William Duellman and L. Trueb, Johns Hopkins University Press, Baltimore, Maryland.
5. Frogs & Toads of the World, 1998. Chris Mattison, Sterling Publishers, New York.
6. From Tadpole to Frog, 1994. Wendy Pfeffer, Harper Trophy, New York.
7. Reptiles and Amphibians, 1992. Harold Cogger and Richard Zweifel. Smithmark Publishers, New York.
8. Simon & Schuster's Guide to Reptiles and Amphibians of the World, 1989. Massimo Capula, Simon and Schuster, New York.
9. Tale of a Tadpole, 1998. Windy Wallace. Dk Publishers, Los Angeles, California.

1. Bullfrogs http://web.uvic.ca/bullfrogs/page2.htm
2. Computer Enhanced Science Education: The Whole Frog Project http://www-itg.lbl.gov/ITG.hm.pg.docs/Whole.Frog/Whole.Frog.html
3. Frogland http://allaboutfrogs.org/froglnd.shtml
4. The Basking Spot http://www.baskingspot.com/
5. Center for Global Environmental Education http://cgee.hamline.edu/frogs/
6. USGS American Bullfrog http://www.npwrc.usgs.gov/nar

Initial development and printing was funded by the Partnership for Arid Land Stewardship (PALS). Project Manager: Karen Wieda. Written by: Ben Booth, Aberdeen School District. Series Editor: Georganne O'Connor; Design: WinSome Design.