Throughout the Northeast, spring rains are creating temporary ponds, known as vernal pools, in woodlands and meadows. Although often small and inconspicuous, vernal pools spring to life as frogs, toads, salamanders and other amphibians converge on them to breed.
Vernal pools provide the temporary aquatic environment that supports the eggs and larvae of amphibians. Because they are isolated from other water sources, vernal pools do not support fish species that would prey upon amphibian eggs and larvae. Despite their name, some vernal pools also fill during autumn.The Greek word “amphibios” means creatures with a double life. Amphibians spend part of their lives living in water and the other part living on land. Most amphibians lay soft eggs in water. An egg hatches into an aquatic larval stage which looks and acts quite differently from the more terrestrial adult stage. For instance, toad and frog eggs hatch into tadpoles, which can only survive in water. As the larvae grow, they experience radical physiological changes and are transformed into adults in a process known as metamorphosis. Many salamanders return to their birth pool to breed. Some salamanders, like the marbled salamander (Amystoma opacum), begin their breeding cycle in the fall, migrating to pools and depositing eggs. Their larvae overwinter in the pool.
Other salamanders, like the spotted salamander (Amystoma maculatum), wait until spring to visit pools and lay their eggs.
Unlike the quiet salamanders, toads and frogs converge on vernal pools to call and attract mates. Frogs produce their calls by moving air back and forth over their vocal cords causing them to vibrate and produce sounds. Even when they can’t be seen, one can identify what frog or toad species are breeding by listening to their calls.
Wood frogs (Rana sylvatica) migrate to vernal pools early in the spring, often before the snow and ice have completely melted. The call of the wood frog is a hoarse clacking sound, reminiscent of a quack. An explosive breeder, the wood frog usually lays a large mass of eggs in a few days and leaves soon after.
The spring peeper (Hyla crucifer), a tree frog, follows the wood frog by a week or two. From February to March, spring peepers leave the trees to mate in open water. Its unmistakable mating call — the peep — and large geographic range make the spring peeper one of the most familiar frogs in North America. Its mating call can sometimes be heard up to half a mile away.
Another familiar amphibian is the American toad (Bufo americanus). Its habitat ranges from mountain wilderness to suburban back yards.
One is likely to find the American toad almost anywhere that is moist and has plenty of insects to eat and shallow water to breed in from March to July. Despite their warty appearance, their mating call is a pleasant musical trill.
Amphibian populations are declining throughout the world. The loss of forest and wetland habitat is one possible cause.
Also, many amphibians return to the ponds and wetlands in which they were born to breed, and if their natal areas are disturbed or lost, these amphibians will not breed.
Deforestation reduces woodlands needed by adults. Fragmentation is also a problem. As wooded tracts shrink in size, the remaining amphibians become isolated and inbreeding may occur, weakening the species.
Why should we care? Because amphibians help us to measure the health of the environment.
Amphibians exchange water and air primarily through their skin. In this process, they can also absorb pollutants present in the soil and water. Like a canary in a coal mine, a decline in local populations may indicate a contamination problem.
Amphibians possess many foul-tasting chemicals in their skin and glands to protect them from predators. Some of these chemicals have been found to have medicinal value. Drug companies are looking to replicate some of these compounds for heart medications, organ glues and pain killers.
Aesthetically, many amphibians are extremely beautiful creatures that we should all have the opportunity to observe and enjoy.
Protecting forested wetlands, woodlands and vernal pools is a first step toward preserving amphibians. But vegetated buffer strips along waterways are equally important. Rivers and flood plains provide excellent corridors to connect isolated woodlands. Amphibians use these corridors to move between small pockets of existing woodlands and wetlands, helping to ensure healthy and diverse populations.
Everyone benefits from preserving amphibians’ habitats, which are also home for a multitude of wildlife including invertebrates, fish, birds and mammals.
Protecting woodlands, wetlands and river corridors also reduces the amount of nutrients and sediment entering rivers and the Bay.
In this increasingly concrete world we all need a place to retreat to. The forests and wetlands offer us such a retreat, to enjoy the serenades from the woods.
Help the Herps
You can help scientists monitor amphibians in your area.
North American Monitoring Program
Patuxent Wildlife Research Center
12100 Beech Road
Laurel MD 20708
Patuxent Wildlife Research Center