Throughout the Northeast, spring rains are creating temporary pools in woods and meadows known as vernal pools. These pools, often small and inconspicuous, are coming alive as frogs, toads, salamanders and other amphibians converge on them to breed.
The Greek word “amphibios” means “creatures with a double life.” Amphibians spend part of their lives in water and part on land. Most amphibians lay soft eggs in water. The eggs hatch 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, a process known as metamorphosis, that transforms them into adults.
Vernal pools provide the temporary aquatic environment that supports both the eggs and larvae of amphibians. Because vernal pools are isolated from other water sources, they do not support fish species that would prey on amphibian eggs and larvae. In spite of their name, some vernal pools also fill up in autumn.
Some salamanders, like the marbled salamander (Amystoma opacum), will actually begin their breeding cycle in fall, migrating to pools and depositing eggs. The larvae overwinter in the pool.
Other salamanders, like the spotted salamander (Amystoma maculatum), will wait until spring to visit pools and lay their eggs. Many salamanders return to their birth pool to breed.
Unlike quiet salamanders, toads and frogs converge on vernal pools and call to attract mates. Frogs produce their calls by moving air back and forth, passing it over the vocal cords, which makes them vibrate and produce sounds.
Even if they can’t be seen, it is easy to identify what species are breeding by listening to their calls.
Wood frogs (Rana sylvatica), migrate to vernal pools early in the spring, often before snow and ice have completely melted. The call of the wood frog is a hoarse clacking sound, reminiscent of a quack. The wood frog is an explosive breeder: It usually lays a large mass of eggs in a few days and leaves soon after.
Spring peepers (Hyla crucifer), a tree frog, follow the wood frog by a week or two. From February to March, spring peepers leave the trees to mate in open water. Their unmistakable mating call, the peep, and large geographic range makes the spring peeper one of the most familiar frogs in North America. The mating call can sometimes be heard up to a half-mile away.
Another familiar amphibian is the American toad (Bufo americanus). Its habitat ranges from mountain wilderness to suburban backyards. One is likely to find this toad almost anywhere as long as there are moist places, plenty of insects to eat and shallow waters to breed in. They breed from March to July. Unlike their warty appearance, the toad’s mating call is a pleasant musical trill.
Around the world, amphibian populations are declining. The loss of forest and wetland habitat is one possible cause. Many amphibians return to the same ponds and wetlands in which they were born to breed. If 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.
Why should we care? Amphibians help us to measure the health of the environment.
They exchange water and air primarily through their skin, and in the process, they can absorb pollutants present in the soil and water. Like a canary in a coal mine, a decline in local populations may indicate a contaminant problem.
Amphibians’ skin and glands contain many foul-tasting chemicals that protect them from predators. Some of these chemicals have medicinal value, and drug companies are trying to replicate some of these compounds for heart medications, organ glues and painkillers.
Aesthetically, amphibians are extremely beautiful creatures that we should all have the opportunity to observe and enjoy.
Protecting forested wetlands is the first step to preserving amphibians. Adults require wooded tracts but need access to shallow aquatic habitats to breed.
Vegetated buffer strips along waterways are equally important. Rivers and flood plains are 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.
We all benefit from such actions. These same areas are also habitat 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 this, including serenades from the woods.
Toad-ally Awesome Ways to Help
Members of the public can help scientists monitor frogs, toads and other amphibians in their area by participating in one of these programs.
North American Amphibian Monitoring Program
Patuxent Wildlife Research Center
12100 Beech Road
Laurel MD 20708
National Wildlife Federation
11100 Wildlife Center Drive
Reston, VA 20190