Frog Decline Has Volunteers Hopping
Limited funds mean more of your neighbors are helping scientists keep tabs on amphibian populations
ACADIA NATIONAL PARK, MAINE — Three evenings a week, rain or star shine, Lori Hildebrandt and her children venture out to their backyard bog for some scientific investigating.
Armed with note pad, flashlight, and their own sharp ears, they listen carefully until a sound breaks the silence: the duck-like quacking of a wood frog, high-pitched chirps of spring peepers,. or the musical trill of an American toad. Quickly they jot down what they hear, then listen attentively again.
As frog-lovers, Ms. Hildebrandt and her children, Gabrielle, 10, and Dominic, 7, are joining more than 30 volunteers this spring and summer in listening for the calls of frogs and toads around Acadia National Park on Maine's Mount Desert Island. They are participating in a volunteer program that will help scientists learn more about frogs and toads - sensitive barometers of the environment - and therefore more about both aquatic and terrestrial ecosystems.
Trained to identify the distinctive sounds of each of the island's eight species, they keep track of what they hear on regular evening forays, then report their findings at the end of the amphibians' four-month breeding season.
Sponsored by Acadia National Park and the College of the Atlantic in Bar Harbor in Maine, the survey is the first at a US national park to use volunteers, and according to park biologist Bruce Connery, it could be a model for others to follow. It is part of a growing network of study projects on amphibians (frogs, toads, and salamanders) - many of which are believed to be declining throughout the US and Canada.
Now in its second year, the Acadia survey has already provided biologists with valuable information on the location of various frog and toad species in and around the park (salamanders are voiceless and therefore are not included in the study). Enlisting volunteers, stresses Mr. Connery, has enabled them to collect far more data than limited funds and personnel would otherwise allow.
The project is also a popular way for people of all ages to spend time outdoors, learning more about their natural world.
"This is something we can do with the whole family," says Hildebrandt, whose husband, Richard, has also participated. "It helps teach the children science and ecology, and is a way we can contribute to our environment," she says. The fact that they must go out after sunset, and often in fog and rain when male frogs and toads tend to call the most, doesn't faze them; Hildebrandt says they enjoy it "no matter what the weather."
But why the focus on frogs and toads? Because most amphibians breed in water but live on land, they play an important role in aquatic and terrestrial ecosystems. The fact that they eat insects but are eaten by birds and mammals, also makes them a critical link in many food chains. Finally, their moist, permeable skin makes them particularly sensitive to pollutants.
Many scientists are therefore concerned that apparent worldwide declines of frogs, toads, and salamanders - especially in the past decade - could be indicative of some larger environmental problem. Some experts suspect, for example, that acid rain, global warming, or increased ultraviolet radiation could be adversely affecting these sensitive amphibians. But despite stepped up studies in recent years, they have yet to identify any single cause of the declines.
At Acadia, levels of ozone pollution are known to be high. But according to Steven Ressel, a professor at the College of the Atlantic who is coordinating the frog survey along with Connery, it could be many years before they determine what impact this and other environmental factors are having on amphibians. The goal of the volunteer survey, he says, is to first create an atlas showing what frog and toad species are present and where, then in subsequent years begin to track any fluctuations in their numbers.
While some question whether citizens can obtain reliable scientific data, most experts agree it is possible. Sally Stockwell, wildlife ecologist for the Maine Audubon Society, says her experience organizing volunteers to conduct a breeding-bird survey shows that with good training they can be extremely thorough in gathering data.
According to Dr. Ressel, this is certainly true of the Acadia volunteers. They learn to identify frogs and toads through photos, onomatopoeic descriptions, and recordings of the males' calls. Hildebrandt says that after a few times outside listening, it becomes relatively easy to distinguish between the different species.
To get consistent reliable data, volunteers are asked to choose a spot near standing water or wetlands, then go there at the same time, at least three evenings a week. In addition to recording the calls and any frogs or toads, they also note weather conditions. And they are cautioned against pursuing the animals since that could scare them away or destroy habitats such as egg-laying sites.
The challenge of the survey, according to Ressel, will be to sustain the effort for enough years to get comparative data. But if this year is any indication, that won't be a problem. He says he and Connery were impressed that over 30 people signed up again to participate, including many from last year. He points to volunteers such as Ron and Helen Taylor, who go out to survey far more than the required three times a week, even when it means walking around in what Mr. Taylor calls his full-body "screen-tent" for mosquito protection. "This is a big commitment," says Ressel, "and many of these people are really taking the study seriously."