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Spring Peepers

Ah, it's finally spring again. The weather is getting warmer, things are getting greener, and the peepers are calling once again. If you have been anywhere near almost any small body of water at this time of year, you have heard their call: a chorus of "peep, peep, peep," repeated about once every second, coming from many individuals. Males use this call to attract mates and it will carry quite a distance. If you ever see a spring peeper, you will be amazed that such a minute creature could produce such a deafening sound. The spring peeper (Pseudacris crucifer) may attain the grand size of just slightly over an inch and is usually brown and gray with a characteristic "X" on its back, making it quite hard to spot in dead leaves and grasses.

In the spring, from February through May here in Virginia, the peepers are drawn from their woodland hibernation sites to ponds or roadside ditches to find a mate and reproduce. The first night with a warm rain will usually bring them out to start their trek to the water. If a particularly cold night occurs after they have emerged from hibernation, peepers will hide under leaves and other debris. This species has been shown to tolerate temperatures down to -6 degrees Celsius for up to five days. This is possible due to the high levels of glycerol in their tissues. The glycerol, which acts as "antifreeze," is only present in peepers' tissues in the winter and is completely absent in the summer.

About 1,000 eggs per female are laid singly in the water and are attached to submerged vegetation at the bottom of the pond. The eggs will hatch into tadpoles in an average of six days and metamorphose into frogs after an average of 45 days. Newly emerged young are about one half inch in length. Adults spend the rest of the year in woodlands under leaf litter or in brushy undergrowth. Some males may continue to call through the summer and fall from trees, which this tree frog can climb with its adhesive toe pads. Peepers are rarely spotted during this time of year, although they are occasionally seen traveling during the day in wet weather. Spring peepers mainly eat small arthropods such as insects and small spiders. Because of their small size, however, they may fall prey to larger spiders.

Frogs are among the animals most sensitive to habitat change. Because they live both on land and in the water, they are susceptible to changes in both of these habitats. From egg to tadpole to adult, each lifestage is vulnerable to different environmental hazards. Because frogs have quite permeable skin and absorb both water and air in this way, they are prone to absorbing pesticides and other pollutants. Frogs have also been shown to be sensitive to the increased UV radiation caused by the thinning of our atmosphere's ozone layer. Frogs are affected by changes in climate that cause droughts, because wetlands are essential for reproduction. All of these factors, plus loss of habitat, have combined to cause the decline of amphibian populations throughout the world.

Because of this sensitivity, frog populations are monitored as an indicator of the overall health of an ecosystem. Many scientists are involved in such research and organizations have been formed to enlist the help of the public. One of these organizations is the North American Amphibian Monitoring Program (NAAMP), a collaboration between state natural resource agencies, nonprofit organizations, and the U.S. Geological Survey. NAAMP trains volunteers in an amphibian data collecting protocol that uses "calling surveys." Trainees learn to identify different frog calls and are taught the correct protocol to follow in data collection. They are then given a road route, which is driven in the evening and has 10 stops where the volunteer listens for five minutes to determine which species are present.

If you are interested in becoming a volunteer for the NAAMP calling survey, contact Don Schwab, the regional coordinator. He can be reached at the Virginia Department of Game and Inland Fisheries, Nongame and Endangered Species Program, in Williamsburg. His e-mail address is dschwab@dgif.state.va.us and his phone number is (757) 253-7072.