About Vernal Pools

At winter's end, woodland hollows and low areas flood, creating temporary isolated pools. The resulting vernal pools fill with melting snow, spring rain, runoff, and rising groundwater. The pools provide seasonal habitat for amphibian and invertebrate species with life cycles that have adapted to these rich temporary habitats.

They’re found in woodlands, meadows, floodplains, and even sandplains all across Massachusetts. They occur in a wide variety of settings including swales, kettle holes, old stream channels, and depressions in larger wetlands.

 

Wildlife of Vernal Pools

Vernal pools provide unique habitat to specialized species. Some animals live in vernal pools year-round, and so must be able to withstand a wide range of conditions from saturated with water to bone-dry or frozen.

wood frog, illustration by Barry Van Dusen
wood frog, illustration by Barry Van Dusen
Easily identified by their dark masks and loud quacking, the Wood Frog (Rana sylvatica) migrates on rainy spring nights to vernal pools to breed. After mating and laying eggs, the adults return to higher ground.

fairy shrimp, illustration by Barry Van Dusen
fairy shrimp, illustration by Barry Van Dusen
The aptly named Fairy Shrimp (Eubranchipus vernalis) are crustaceans who seem to have magic survival powers. They hatch and develop early in the season, before most predators arrive. Their hardy eggs stay in the pond's dry sediment, resistant to drought and cold, and can even survive being ingested and then eliminated by animals.

spring peeper, illustration by Barry Van Dusen
spring peeper, illustration by Barry Van Dusen
You are far more likely to hear the sharp peeping call of the tiny Spring Peeper (Pseudacris crucifer) tree frog, than to see one. Though they're only about an inch in size, their calls carry for a quarter-mile. 

spotted salamander, illustration by Barry Van Dusen
spotted salamander, illustration by Barry Van Dusen
Spotted Salamanders (Ambystoma maculatum), named for their distinctive yellow spots, live in woodlands. On rainy early-spring nights, they migrate up to a half-mile to breed in vernal pools. They gather in a congress–a pool of mating spotted salamanders.

caddisfly larvae, illustration by Barry Van Dusen
caddisfly larvae, illustration by Barry Van Dusen
Caddisfly Larvae (classInsecta, order Tricoptera), like numerous other insect larvae, thrive in vernal pools but can also breed in other wetlands. Caddisflies construct their own protective cases from stems, leaves, and woody material.