One of spring's most characteristic sounds is the song sung by frogs. If you walk into the woods or beside a field or along a ditch or stream on any warm evening, you may hear the calling of frogs. Except for a few species, only males make vocalizations, and they may use several different types of calls. One specific call is used to defend territory. Another is used in distress, such as when a frog is attempting to escape from a predator. A third type is used by a male to let another amorous male know it is not a female, but the most commonly used is the vocalization intended to attract a female.
Each species of frog makes a distinctive sound which is produced by moving air through a vocal sac that inflates below the frog's mouth. The call enables females to find suitable mates. It also lets people identify the different species of frogs present in an area even if the individuals can't be seen.
Frog species have different breeding seasons. Wood Frogs, for example, breed for a short period in late winter. Many treefrogs breed in late spring or summer. Spring Peepers have a long breeding season, from February to June. Some frogs, such as the Eastern Spadefoot, are identified as "explosive breeders" because large numbers come together en masse for brief times during heavy rains.
Listen to the calls of various frog species: "Frog Call Lookup," produced by the Patuxent Wildlife Research Center of the U.S. Geological Survey
Identify a frog: "All Living Things: Anura," a tool for species identification developed by Discover Life, a project sponsored by the National Science Foundation; University of Georgia, Athens; and others.
Learn about the importance of frogs in the environment: "Virginia Is for Frogs," produced by Virginia's Department of Game and Inland Fisheries.
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