If you are walking along a forest path or wooded road in the next few weeks, keep an eye out for the Spotted Salamander. This shiny, wet-looking amphibian ranges in color from black to blue-gray to brown, with two rows of yellow or orange spots trailing from its head to the tip of its tail. It can grow to up to seven inches long.
Now is the time of year when Spotted Salamanders begin their annual migration to their breeding grounds. You can often see them in wooded areas, silently crossing streets or forest paths on rainy nights. On the South Shore, this is especially the case in March or April, once the ground has thawed. The first heavy rain when the air temperature is above freezing tends to bring on a mass movement of migrating salamanders. They are on their way to a vernal pool, where they will mate and lay their eggs.
The typical habitat of the Spotted Salamander is woodland. A salamander will inhabit an abandoned burrow or any other small cavity in the forest floor. However when the weather grows warm, these salamanders move to shallow pools, traveling up to a mile to return to the place where they were born.
The males arrive first, and the females are not far behind. Courtship ensues, and after the male deposits a gelatinous capsule of sperm on the vernal pool’s floor, the female takes this capsule into her body to fertilize her eggs. The female lays these eggs -- up to 200 in number -- in a single mass in the water. After breeding, the adults leave the pool, and on another rainy night return to the forest.
As the water in the vernal pool warms, tiny larvae emerge from the eggs. By August or September the little salamanders have matured to adulthood. They will spend the fall and winter burrowed into the bottom of a pond or beneath the leaf litter of the forest floor.
But what are vernal pools? And where might you find one? A vernal pool is a temporary shallow pond that appears or grows considerably in the spring as melting snow, spring rains, and/or elevated groundwater tables bring increased water supplies. It often dries up in late summer.
Because of the changing nature of vernal pools, the animals who inhabit them either leave when conditions no longer suit them, or go dormant until conditions return to their liking.
Vernal pools are an important wildlife habitat, essential to preserving biological diversity. A wide range of species of amphibians and insects depend on their presence for a safe breeding ground. Because the pool is not permanent, there are no fish to eat the eggs or larvae. Vernal pools also provide watering sites for the animals who inhabit the area.
Plants, such as the highbush blueberry, dogwood, and sweet pepper bush, which are tolerant of seasonal flooding, grow in the rich soils at the edges of the vernal pool. These, along with fallen leaves from nearby trees, eventually decay, providing nourishment for the worms, fairy shrimp, and insects that live in the pool. These creatures in turn become food for vernal pool-dwelling salamanders and other amphibians, plus reptiles and birds.
A wide array of salamanders, including the Jefferson’s, Marbled, and Four-Toed varieties, inhabit vernal pools. Other species that can be found there include Red-spotted Newts, Wood and Green Frogs, American and Fowler’s Toads, and the Spring Peeper. Plus turtles, fingernail clams, amphibious snails, scores of insects, and much more. Why not put on your boots and go explore one?
Vernal pool sites include the Jacobs Pond area in Norwell, Pembroke’s Misty Meadows/Herring Run Conservation Area, and Marshfield’s Carolina Hill, especially the section near Eames Way School.
by Kezia Bacon, Assistant Director, North and South Rivers Watershed Association
March 1997
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