Wetlands Functions and Values
The sounds of red-winged blackbirds and woodcocks, the presence of robins and crocuses: all signal the arrival of spring to New England. However, it's when frogs and salamanders (collectively known as amphibians) begin their breeding season that we know that spring is here to stay. From numerous small depressions in the landscape filled with water from spring rains and melting snow come the sounds of chorusing frogs: the quacking of wood frogs, peeping of spring peepers, and whistling of American toads. In these small temporary pools, called vernal pools, salamanders court and lay eggs following a spectacular migration from woodland wintering sites. Each year on the first warm rainy night of spring, millions of amphibians across Massachusetts use this "big night" to migrate to vernal pools in order to breed.
Vernal pools are confined basin depressions that fill with rain and snow meltwater in the spring and hold water for at least two continuous months. In the spring and early summer they are full of life: tadpoles and salamander larvae, fairy shrimp, fingernail clams, aquatic insects, spotted turtles, and wood ducks. By late summer these pools are typically dry. Because they are dry for part of the year, vernal pools lack fish. The absence of fish, which would prey on amphibian eggs and young, makes vernal pools preferred breeding habitats for many of our native amphibians.
Two-thirds of the state's amphibians use vernal pools for breeding. Vernal pools are the nearly exclusive breeding habitat for 30 percent of the amphibian species native to Massachusetts. Among these, the wood frog and spotted salamander are the most common. More significantly, most of the state's rare amphibians breed primarily in vernal pools. These include blue-spotted, marbled and Jefferson salamanders, and the eastern spadefoot toad. These small temporary ponds also provide for state-listed spotted turtles and rare invertebrates, such as the intricate fairy shrimp and Massachusetts clam shrimp.
During the brief spring/summer season, vernal pools are highly productive habitats. Tadpoles and salamander larvae develop quickly, racing against time to grow and transform into terrestrial sub-adults before the pool dries up. As juvenile amphibians disperse into surrounding woodlands and fields, they transport much of the vernal pools' productivity into terrestrial habitats where these amphibians are eaten by numerous predators, such as raccoons, opossums, snakes, shrews, turkeys, bears, hawks and owls.
Scattered throughout New England, vernal pools are important features of the forested landscape. They are generally protected by various state regulations, including the state's wetlands regulations. In some communities, such as Haverhill, vernal pools are also protected by local wetlands bylaws or ordinances. In many cases, primary responsibility for protecting these vital natural resources rests with local conservation commissions. For more information about vernal pools and how they are protected, contact the Haverhill Conservation Department. The Department may also be able to suggest ways to get involved in protecting vernal pools and other wetlands in Haverhill.