Monday, April 21, 2008

Vernal backyard pools

From Stef '06 at the DEP:

Are There Pools in Your Back Yard?

Spring is here, with its special sights and sounds.
On a rainy night when the temperature is above 40 degrees you can not only hear the chorus of frogs but see Maine's wonderful amphibians. Keep your eyes peeled for frogs and salamanders coming out of the woods, crossing your yard, the road, or whatever obstacle might be in their way. These critters are making their annual migration from winter habitat to breeding habitat – they are headed for vernal pools.
Vernal pools (vernal comes from the Latin word for spring) are generally small depressions in the woods that fill with water during spring and fall, and frequently dry up in the summer. These woodland pools don't have fish living in them, and don't have an inlet or outlet that would allow fish to get to them. That's why they make great nurseries—no fish to eat the eggs, tadpoles, and baby salamanders!
In fact, in Maine, vernal pools provide the primary breeding habitat for wood frogs, spotted, blue-spotted, and four-toed salamanders, and fairy shrimp. They also provide critical habitat for some endangered species such as the Blanding's turtle and the ringed boghaunter dragonfly.
Vernal pools are valuable to many other animals as well. All of those hundreds of eggs that the frogs and salamanders lay are meals for hungry skunks, weasels, and other larger animals including bears. Other animals such as deer and moose visit the pools in early spring for fresh leaves because vernal pools tend to green up earlier than the rest of the woods.
The surviving eggs hatch within a few weeks, and tadpoles and larvae emerge. Once the young frogs and salamanders leave the pool, they are still hunted by skunks and weasels and lots of others looking for food.
The frogs and salamanders that survive make their way to either a forested swamp or some dry part of the woods to spend the summer. Wood frogs have been shown to migrate up to 1000 feet from the pond they were born in to find summer habitat – that's a long way for an animal that small!
Next spring, this new generation of frogs and salamanders will make their way back to the same vernal pool in which they were born, to start the process all over again. It is important to protect not only the vernal pool itself, but also the land around the pools, since many organisms spend most of their lives in the surrounding areas. Effective September 1, 2007, a new law enacted by the Maine Legislature is helping to protect the vernal pools and surrounding areas to make sure this continuing cycle of life can take place.
To learn more about vernal pools go to and click on the Keyword "vernal pools" for more information.
This column was submitted by Mary Pierce, formerly an Environmental Specialist with the Maine Department of Environmental Protection's (DEP) Bureau of Land and Water Quality. In Our Back Yard is a weekly column of the DEP. E-mail your environmental questions to or send them to In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333.

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