WASHINGTON POST (DC) 03 April 08 Patuxent Patrol: On Frog Alert in the Dark of Night - Listening for a Chorus Of Melodic 'Rrrribbit' (Andy Zieminski)
Seven people marched through the nighttime darkness in Upper Marlboro's Patuxent River Park on March 26, barely able to make out the trees, water and wildlife that normally attract visitors.
But that did not matter, because they were there to listen.
"You can hear toads real well in this direction," said Bowie resident Mike Quinlan, thrusting his arm toward an unseen stream in the woods, where a few of the amphibians were croaking in long trills.
The park employees and area volunteers were conducting a frog survey, a type of census that park naturalists started this spring in hopes of keeping track of the frog population over the coming years.
The project is part of a national program started in 2002 called Frogwatch USA, a joint effort of the nonprofit National Wildlife Federation and the U.S. Geological Survey. The organizations are trying to study and draw attention to declining amphibian populations, according to Frogwatch USA's Web site.
One goal of the program is to encourage volunteers to track frog populations in their own neighborhoods. Volunteers, such as the Patuxent group, collect data on roughly how many frogs they find in designated areas and enter the data online. They do not try to tally individual frogs, but rather gauge their numbers by assessing the volume of their calls.
"We might not be able to see them, but we can tell by hearing them that there's a few or [a] whole bunch," said park naturalist Stephanie Jacob, who is leading the Patuxent River Park survey.
Keeping track of frog populations is important because the creatures are an "indicator species to what's going on in the environment," Jacob said. Frogs have porous skin, making them sensitive to pollution in the air and water, as well as to long-term temperature changes, she said. They also tend to vanish from areas when human development encroaches on their habitat. Frog populations are fairly healthy in the Patuxent River park because it is large and protected against development, Jacob said.
But the same cannot be said for other parts of the county.
Volunteer Bonnie Campbell said that when she moved to Mitchellville 17 years ago, she and her family frequently saw toads around their house.
"But now we don't see them anymore," said Campbell, who participated in the survey with her daughter, Kellie Robinson, and grandchildren Matt and Mary.
The volunteers were required to attend a training session in February, when they looked at pictures of 19 species of frogs that live in the park and listened to their calls on a CD.
"They have pretty distinct sounds," said John Duvall, a Marlton resident and part-time park employee. "At first, they may not, but as you listen, you'll pick up different tones and sounds."
The Patuxent group planned to visit four locations in the park over seven Wednesday nights in March and April, the breeding season and most active time of year for many of the park's frog species.
Group members go out about a half-hour after sunset, when the frogs begin to call.
At each site, all near bodies of water, the volunteers listen silently for three minutes and then apply a four-point scale to how many of each frog species they heard. They mark zero if they hear nothing, one for a few distinct individual frogs, two for a chorus in which individuals could be picked out, and four for a chorus in which no individuals could be picked out.
Campbell, the volunteer from Mitchellville, said the survey has educated her about the sounds of outdoors. Before, she said, "I would have said, 'Listen to those crickets over there. They sure are loud.' "
On Frog Alert in the Dark of Night