Every spring, on the first rainy days and nights, a strange quacking sound draws me to the woods. Following the sound, I’ll make my way to a small pond in the woods where what I already know is confirmed – it’s not the sound of ducks, but the sound of wood frogs! Wood frogs are one of a handful of wildlife species that use vernal pools – wetlands that dry up every year, or every couple of years. Vernal pools are unique and important habitats for a variety of wildlife species in New Hampshire and they are a bustling with activity in springtime.
Fish are normally top predators in wetlands, but they can’t survive in pools that dry out. As a result, vernal pools provide key breeding habitat for amphibians whose tadpoles and larvae are especially vulnerable to fish predation – wood frogs, spotted, blue-spotted, and Jefferson’s salamanders. In the spring, these amphibians migrate from nearby woodlands to vernal pools, where they breed and deposit their eggs. Once hatched, tadpoles and larvae develop quickly into young frogs and salamanders that must leave the wetland before it dries up – by early or mid-summer for wood frogs, or by late summer or early autumn for salamanders. Fairy shrimp, small crustaceans, also require vernal pools for breeding.
In addition to these species that require vernal pool habitats, there are many other species that use vernal pools throughout the year, but especially in the spring. Spotted and Blanding’s turtles use vernal pools extensively as they travel across the landscape, likely drawn to them as a good source of food – with lots of amphibian eggs, tadpoles, and insects to eat. Great blue herons, snakes, raccoons, and even barred owls are also drawn to these habitats to feed on the abundance of food found in vernal pools each spring.
Vernal pools can exist almost anywhere—in forests, fields, shrub swamps, marshes, or even in gravel pits. They can be smaller than one-tenth acre or larger than two acres. Vernal pools occur as isolated wetlands (not connected to other wetlands), as part of larger wetlands (for example, a vernal pool within a scrub-shrub swamp), or in floodplains along rivers. Vernal pools are found throughout New Hampshire but are most common in the flatter regions of central and southeastern New Hampshire. Because they’re scattered across the landscape and are easy to miss when they are dry, they are easily overlooked in wetland inventories. As a result, most vernal pools haven’t been adequately mapped, and scientists don’t know how many pools have already been lost to development. Without these critical habitats on the landscape, we would lose the unique set of species that require them to complete their life cycle. It’s important to note that most of the species that require vernal pools for breeding actually spend most of the year in the forests around the vernal pools, so the upland areas around these pools are also critical to the survival of these unique species.
What can you do to help protect vernal pools?
Map: The first thing you can do is help find and map them, whether on your own land or on town lands – knowing where these wetlands are is the first step in protecting them. There are some great resources out there for learning how to identify and document vernal pools. NH Fish and Game has developed a detailed guide to Identifying and Documenting Vernal Pools in New Hampshire. The Harris Center for Conservation Education has a volunteer program devoted to finding and documenting vernal pools in the southwestern part of the state, and maintains some great resources for anyone interested in learning more.
Conserve: Land conservation is another great tool for protecting vernal pools, since permanent protection of land ensures that vernal pools and the surrounding uplands are safe from any future development. You can work with your town conservation commission or local land trust to protect these important habitats on your own land or in your community.
While New Hampshire does have permitting requirements in place to protect wetlands and surface waters (RSA 482-A), the upland areas surrounding vernal pools lack protection at the state level. Town conservation commissions and planning boards can work together to develop or update zoning ordinances that protect vernal pools. This is often accomplished with a Wetland Zoning/Protection Ordinance that defines and protects buffer areas around vernal pools and other wetlands.
Share: Teaching others about vernal pools is a great way to spread the word about these important habitats. Vernal pools are beautiful and fun, and people love learning more about them. The more people know about these habitats, the easier it is to protect them going forward.
By Emma Tutein, Natural Resources and Land Conservation Field Specialist, UNH Cooperative Extension
2021 Taking Action for Widllife Newsletter