Polk County Conservation

Frogs and Toads of Iowa

This podcast was produced by Polk County Conservation and funded by Resource Enhancement and Protection Conservation Education program or REAP-CEP.

Hi, my name is Heidi Anderson. I am a naturalist with Polk County Conservation.

Frogs and toads are good indicators of the health of our environment because they absorb oxygen through their skin. Researchers worldwide have noted for years that many species of frogs and toads are declining. The decline is thought to be the result of habitat loss, excess UV radiation caused by thinning of the ozone layer, disease, increase in pollution and overuse of pesticides. In response to the decline, the Iowa Department of Natural Resources Wildlife Diversity Program has developed an auditory survey for calling frogs and toads to determine distribution across the state. These auditory surveys are done by volunteers.

When frogs and toads awake from hibernation, the males begin to establish territories and find a mate. To do this, male frogs position themselves in a body of water and sing. As the evenings become warmer, more frogs join in the chorus and the pitch rises. Female frogs are attracted to the persistent calls of the males.

There are a variety of frogs and toads volunteers listen for. Some of the first frogs heard in the spring are Western chorus frogs. These small frogs are a little over a 1 inch long and its call sounds like someone running a fingernail over the teeth of a comb. They usually call from a few inches of water in flooded, grassy areas.

Another frog you may hear in the spring is a cricket frog. Their call sounds like two marbles hitting each other in a series of rapid clicks. The sounds of cricket frogs can be heard a half mile away or more. Cricket frogs have excellent camouflage to blend into muddy stream banks.

The American toad is another active singer. The call of an American toad is a high loud trill that lasts for several seconds, sometimes half a minute. Toads are abundant throughout Iowa, especially in forested areas.

Gray tree frogs can be heard throughout city neighborhoods in Iowa. Typical of tree frogs they have suction cups on the ends of their toes to cling to wet leaves or the stems of plants. Their call sounds like a musical trill that sounds as if the frog is singing under water.

Later in the summer the calls of bullfrogs drown out other frog calls in many ponds and lakes. The bullfrog is largest frog in Iowa growing up to 6-8 inches long. Bullfrogs live in quiet, permanent water that is deep enough to support tadpoles through the winter. The bullfrog call is very deep sounding like the bellow of a bull.

The future of Iowa’s amphibians is directly related to the quality of our water. Keeping our water clean is a responsibility we all share. Good water quality will ensure these vocal animals will continue to sing.

To find out how you can participate in the Iowa Frog and Toad Survey, visit www.iowadnr.com. Polk County Conservation manages 16 different parks and trails in Polk County and frogs can be heard at many of them. The next time you’re out in a natural area; listen for the calls of these special animals.

This podcast was funded by REAP-CEP which is a program the State of Iowa invests in to enhance and protect the state's natural and cultural resources. REAP provides money for projects through state agency budgets or in the form of grants. For more information about REAP, visit www.iowareap.com

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