- The Washington Times - Wednesday, April 19, 2006

It’s a warm evening in late March, and a group of trained volunteer naturalists clusters at a marsh inside the U.S. Fish & Wildlife Service’s Patuxent Research Refuge in Beltsville.

They’re here at the refuge’s central tract, one of the Washington area’s prime spots for frog-watching, to track the mating calls of the marsh’s 12 species of frogs and toads. It’s a census, in effect, and it’s one way to learn whether the marsh’s share of this order of animals, which is in worldwide decline, is holding its own.

The frogs don’t care. It’s spring, and they want mates, now. As the listeners take their posts, they hear what they’ve come to hear: Several high-pitched singers, all male spring peeper frogs no bigger than a human thumb, begin a melody.

Coming from somewhere behind the cattails to the left, the peepers’ song swells to a chorus. Two listeners cup their ears to amplify and catch each nuance of the froggy reprise.

They soon pick up a rhythmic staccato bass line — like the sound of several jolly old men chuckling — interrupted by a series of alto trills from the trees on the distant side of the marsh, from toads keening with longing and passion.

The songs enthrall the three humans, too, as they return to their sport utility vehicle, borrowed from the U.S. Fish and Wildlife Service for the evening because its ruggedness suits the rutted roads of the refuge.

“I heard spring peepers, leopards and a few gray treefrogs,” says Art Abrams of Greenbelt, 49, using the shorthand term for leopard frogs.

“Definitely,” answers Lutz Rastaetter, another Greenbelt resident in his late 40s, “and it was almost a chorus.”

The group members can barely see in the dim light of a new moon, so they turn on a car light to fill out their data sheets.

They note the species calling — pickerel frogs and American toads as well as the peepers, leopards and gray treefrogs — the approximate numbers calling (individuals, overlapping callers, or a chorus), the time, the exact temperature, wind levels and any background noises, such as passing cars, that may have interfered with the calls of the lust-filled frogs.

They will move on to their next listening post, a shallow 2-acre pond. Their data will be tabulated and stored by refuge biologists for researchers’ use and later will be added to an ever-increasing database of knowledge on frog populations.

Ain’t easy being green

Herpetologists, scientists who study reptiles and amphibians, have recognized that over the past 50 years, many species of amphibians, including frogs and toads, have declined markedly worldwide. Whole species — such as Costa Rica’s golden toad and Australia’s gastric brooding frog — have become extinct.

In the lower 48 states, four species of frog and three species of toad, most of them in the Southwest, are listed as threatened or endangered by the U.S. Fish and Wildlife Service.

In many cases, the falloff in numbers can be traced to human influence, according to the Declining Amphibian Population Task Force, an international nonprofit group set up in 1991 under the World Conservation Union in Switzerland to determine the extent and cause of amphibian decline worldwide.

Habitat loss is a prime culprit, according to the DAPTF. Deforestation, the draining of wetlands where amphibians usually live, and the effects of pollution all contribute to the loss of amphibian living space.

However, since 1988, frog numbers in even pristine habitats such as national parks and nature reserves have dropped in some areas at an unexpectedly fast pace.

News such as that has prompted many to join the frog watch.

“Our changes to the climate and our increases in pollution have diminished frogs’ numbers and threatened their existence,” says Laurel resident Stan Hopkins, a semiretired frog surveyor who participates in both the Patuxent survey and the U.S. Geological Survey’s Frogwatch USA for Howard County.

“This needs to be documented and reported,” he says.

How many frogs?

To track any further declines, in 2001 the U.S. Geological Survey began the North American Amphibian Monitoring Program (NAAMP), which set up frog-call surveying procedures to contribute to the frog population database.

“While we were already tracking frog population levels in a limited way, reports of frog malformations and deformities widely reported by the press in the late 1990s definitely speeded up our efforts,” says NAAMP National Coordinator Linda Weir, who is headquartered at the USGS’s Patuxent Wildlife Research Center.

A frog and toad census of the entire United States is a big order — and means that volunteers are vital because there simply are not enough government biologists to spare to take a nationwide frog survey.

So NAAMP set up training sessions and developed a network of nationwide coordinators who train volunteer naturalists to identify local species by learning their calls.

“The goal is to assess population trends and see if they are increasing or decreasing,” Ms. Weir says.

Frog-calling surveys have been carried out by volunteers at the Patuxent Research Refuge since 1997, but since the advent of the monitoring program in 2001, their procedures have been modified to match those of the NAAMP, says Patuxent Research Refuge wildlife biologist Christopher Wicker.

Noisy in love

The NAAMP program goes into gear each year during the amphibian breeding season, spring and summer, when male frogs begin trumpeting their virtues. Only the males call; female frogs are mute unless startled.

The program relies on participants who go out in the evening, beginning one hour after sunset, and note the level of frog calls, by species, at each of 10 listening stations along three established roadside routes within the refuge.

In the Piedmont region of Maryland and Virginia closest to Washington, volunteers are trained to identify the calls of the dozen or so frog and toad species typically found in this region. Each species has an entirely different call, and none of them in our area sounds like the stereotypical “ribbit.”

In fact, the frogs and toads around here emit calls that sound very different: like nails being hammered on shingles (the wood frog); like someone running a finger over a comb (the chorus frog); like the grunts and snores of a restless sleeper (the pickerel frog); or like metallic balls clicked together (the cricket frog).

Most frog calls are mating calls, but some species will emit a warning “squeek!” or will cheep loudly when they are startled or if they are picked up suddenly and examined by a human.

Some male frogs will sound out an “antagonistic” call, which can resemble another species’ sound, if they are grabbed accidentally by another male during the spring mating frenzy.

“The antagonistic call is basically a ‘Get off me’ call,” U.S. Fish & Wildlife Service biologist Marilyn Eames tells volunteers during her training sessions at Patuxent.

Frog songs can be soft, melodic and pleasant, such as the trill of the gray tree frog, or as deafening and obnoxious as the loudest heavy-metal rock concert. Surveyors listening to a loud chorus of hundreds of spring peepers in late April sometimes have to cover their ears to protect their eardrums from the din.

‘Nature deficit disorder’

A separate program called Frogwatch USA was founded by the U.S. Geological Survey in 1998 at Patuxent Research Refuge to study the distribution of frogs and increase ecological awareness among local residents. The National Wildlife Federation, a private nonprofit group, helps USGS administer the program by recruiting and training volunteers to serve as frog surveyors.

Interest in participating in Frogwatch is strongest in New England, the Mid-Atlantic states and California, but the program’s leaders have encouraged volunteers from all 50 states.

Somewhat less structured than the NAAMP program, Frogwatch emphasizes citizen education and gives special attention to children.

“The program provides an opportunity for residents to become ‘citizen scientists,’ giving them that ‘econnection’ with the environment,” says Sue Muller, a natural resource technician with Howard County Recreation and Parks, which runs one of several Frogwatch programs in the Washington area.

“With a generation growing up on computers, Frogwatch USA gives children an avenue to follow, leading them outdoors and away from their computer screens, to learn about nature.”

Ms. Muller calls this “a step in the right direction for dealing with ‘nature deficit disorder.’ ”

Howard County began participating in Frogwatch in 2000 and monitors 35 sites on county parkland. But the favorite breeding spots of all species in the county has yet to be mapped.

“Frogwatch USA is still young,” Ms. Muller says. “We’ll need years of data before population trends can be determined.”

Training to listen

Both NAAMP and Frogwatch USA provide plenty of training in identifying frog calls for its volunteer participants.

Generally, trainees sign up in the late winter and are given basic information about the refuge or park they will survey. They are instructed in the procedures and then sit through a three- to four-hour slide show that teaches them about the species for which they will listen.

At the training session, volunteers listen repeatedly to taped or CD versions of the frogs’ calls, and trainers prompt them to develop their own mnemonic tricks to remember each one. For example, a trainee may write down the letter “L” for leopard frog, because “leopards make a Laughing sound.”

Most participants are given copies of frog-call tapes so they can practice at home, and NAAMP even has set up an online quiz to make certain that volunteers know their frog calls cold before collecting data.

The calls don’t always sound the same in nature as they do on tape, so most volunteers tag along for at least one survey with more experienced frog surveyors who will help them sort out which species they are hearing.

It really isn’t too difficult to learn the different frog calls, says Mr. Hopkins, the frog surveyor for both the Patuxent survey and Frogwatch.

He uses mnemonics, keeps a “cheat sheet” and has relied on commercially available CDs to reacquaint himself with the calls each year.

For him, that’s a pleasure, and one more opportunity to get in touch with nature.

“It’s fun to be part of the night scene at Patuxent,” he says.

Joining the frog monitors

Saturday is Earth Day, the perfect time to volunteer as a frog surveyor. It takes commitment and a bit of training, but tracking a declining population and keeping in touch with nature can be powerful incentives.

Here are some local organizations to get you started:

• Frogwatch USA: A long-term frog and toad monitoring program begun by the U.S. Geological Survey in 1998 and managed since 2002 in partnership with the National Wildlife Federation. Watchers are active in most states, but they concentrate in the Northeast and Mid-Atlantic states and California. Frogwatch aims to increase awareness of amphibian decline and gives volunteers the chance to gather information that can help stave off extinction. See nwf.org/frogwatchUSA

• Local coordinator: Matt Gribbin, National Wildlife Federation, 11100 Wildlife Center Drive, Reston. 800/247-7387, Ext. 6177.

• Public Frogwatch session: Font Hill Park, 3520 Font Hill Drive, Ellicott City, Md. 7 p.m. April 23. Contact Sue Muller at 410/313-4697 or at [email protected]

• The North American Amphibian Monitoring Program (NAAMP): A joint effort of the U.S. Geological Survey (which provides central coordination and database management) and regional partners (which recruit and train volunteer observers to collect amphibian population data). For full information and for the “frog call quiz” mentioned in the story, see www.pwrc.usgs .gov/NAAMP.

• Maryland Coordinator: Wayne Hildebrand in Keymar, Md., at [email protected]

• Virginia Coordinator: J.D. Kleopfer, Virginia Department of Game and Inland Fisheries in Williamsburg, at [email protected]

• Patuxent Research Refuge: Scarlet Tanager Loop, Laurel. Established in 1936 and comprising 12,750 acres, Patuxent is one of more than 500 refuges in the National Wildlife Refuge System administered by the U.S. Fish and Wildlife Service. However, it’s the nation’s first and only national wildlife refuge devoted to wildlife research. See www.fws.gov/northeast/patuxent/volunteer.html.

Frogs, toads at home here

Even for trained listeners to the calls of frogs and toads, it’s often difficult to tell the differences among the species. Then again, in our area, listeners have to keep track of just a dozen species. Here’s a list of the frogs and toads found in the Washington area:

• American bullfrog (Rana catesbeiana)

• Gray treefrog (Hyla versicolor)

• Green frog (Rana clamitans)

• Northern cricket frog (Acris crepitans)

• Pickerel frog (Rana palustris)

• Southeastern chorus frog (Pseudacris feriarum)

• Southern leopard frog (Rana sphenocephala)

• Spring peeper (Pseudacris crucifer)

• Wood frog (Rana sylvatica)

• American toad (Bufo americanus)

• Eastern Spadefoot toad (Scaphiopus holbrooki)

• Fowler’s toad (Bufo fowleri)

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