Maggie's Farm

Vernal Pools are (usually temporary except in high-rain years) marshes. "Wetlands,"  aka swampy areas. They are a cool and productive part of an ecosystem because they contain no fish or turtles to eat all of the baby amphibians.

Generally the spring pools are fed by snow melt, early Spring rain, or slow seeps from springs which do not produce enough water to keep the area wet in high summer.  Springs are interesting things.

Critters that breed in vernal pools clearly need to lay eggs which produce rapidly-maturing young who can leave the pools before they dry up.  For example, Bullfrog tadpoles take a long time, up to a year, to grow and mature via that crazy amphibian metamorphosis so large frogs require permanent bodies of water.

Around here, typical Vernal Pool breeders are Spring Peepers, Common Toad, Wood Frog, Cricket Frog, various salamanders. Spring Peeper eggs - tadpoles - tiny frogs are ready to leave the water in 8 weeks. Toads can do it in 12 weeks.

Here's a nice brief post about New Jersey's vernal pools.