Vernal pools are small temporary, fishless water bodies. Woodland amphibians including wood frogs, mole salamanders (yellow & blue spotted salamanders, Jeffersons) and a variety of invertebrates including fairy shrimp depend on vernal pools as breeding sites. "These waters differ from other freshwater habitats in their alteration between extended flooding and periodic drying. This distinguishing hydrological cycle gives aquatic animals enough time to complete their life cycle during the flooded phase, while drawdown keeps out fish and allows for production of nutritious food from the damp, decaying leaves. Lacking predatory fish and offering abundant food, vernal pools provide specialized habitats for a remarkable variety of wildlife species. (Colburn, Vernal Pools: Natural History and Conservation, p.2)"

The small and shallow pools are highly active with amphibian breeding in early spring. The chorus of wood frogs can be heard throughout the spring and often egg masses (of frogs and salamanders) can be seen along the surface of the pools clinging to high bush blueberry and other wetland shrubs.

"The Big Night" phrase refers to the annual migration of mole salamanders and other amphibians back to their ancestral breeding pools (vernal pools or woodland wetlands). This occurs after a big rainfall when the temperature is above 40 degrees at night.

Southern Maine is full of vernal pools, and many of GWRLT preserves are dotted with them. We are offering two guided Vernal Pools outings at our Tatnic Woods preserve in Wells this spring: "Vernal Pool Walk," with naturalist Sue Bickford, April 16th, 9-11am & "Stories in the Woods: Vernal Pools" with vernal pool nerd and Outreach Coordinator, Brenna Crothers, April 21st, 10-11am (this outing is for young families with children ages 2-5, siblings welcome). If you are unable to attend we do have a few trails that take you by vernal pools, Tatnic Woods and Payeur Preserves. *Remember when visiting vernal pools these habitats are highly sensitive, keep all animals out of the pools.* Learn more about the big night and vernal pools from this article by Sue Pike It's a perfect time for the Big Night of amphibian migration.