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Throughout the Northeast, temporary ponds known as vernal pools are coming to life as frogs, toads, salamanders and other amphibians converge on them to breed. The pools form as shallow depressions in forests, flood plains and meadows fill with water from rain, snowmelt and high water tables.
Because these vernal pools are isolated from other water sources, they do not support fish species that would prey on amphibian eggs and larvae, making them a secure place for these animals to reproduce.
The Greek word "amphibios" means creatures with a double life. Amphibians spend part of their lives living in water and the other part on land. Most amphibians lay soft eggs in water. The eggs hatch into an aquatic larval stage that looks and acts quite differently from the more terrestrial adult stage. For instance, toads and frogs eggs hatch into tadpoles, which can only survive in water.
Despite the label "vernal," which means spring, some of these pools also fill during autumn, creating the perfect breeding habitat for amphibians like the marbled salamander (Amystoma opacum). Marbled salamanders 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.
Unlike quiet salamanders, toads and frogs converge on vernal pools and call to attract mates. Frogs produce their calls by passing air back and forth over the vocal cords, which causes them to vibrate and produce sounds. Even if one cannot see the frogs or toads, they can be identified 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.
Probably the most familiar vernal pool visitor is the spring peeper (Hyla crucifer), a tree frog that 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 recognizable frogs in North America. The mating call can sometimes be heard up to a half a mile away.
Another familiar spring breeder is the American toad (Bufo americanus). Their habitat ranges from mountain wilderness to suburban backyards. One is likely to find the American toad almost anywhere as long as there are moist places, plenty of insects to eat and shallow waters to breed from March to July. Despite their warty appearance, their mating call is a pleasant musical trill.
Because amphibians require such unique habitat conditions to breed, they are also very vulnerable to land use changes by people. Many amphibians return to the same ponds and wetlands in which they were born to breed. If these natal areas are drained or filled, those amphibians will not breed.
Because these animals need both an aquatic environment to reproduce and develop, and a terrestrial environmental for the rest of their life, the loss of the woodlands surrounding their seasonal pool can be devastating. As wooded tracts shrink in size, an amphibian population can become isolated and inbreeding may occur, weakening the species.
Why should we care? Amphibians help us to measure the health of the environment. Amphibians exchange water and air primarily through their skin. In addition, they can absorb pollutants that are in the soil and water. Like a canary in a coal mine, a decline in local populations may indicate a contaminant problem.
Amphibians possess many foul-tasting chemicals in their skin and glands to protect them from predators. Some of these chemicals 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 and woodlands is one of the first steps 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 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 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, everyone needs a place to retreat to. The forests and wetlands that provide these serenades are such a place.
To help scientists monitor frogs, toads and other amphibians in your area, contact: North American Amphibian Monitoring Program at the Patuxent Wildlife Research Center by calling 301-497-5500 or visiting www.pwrc.usgs.gov/naamp/
This article credits Bay Journal News Service http://www.bayjournal.com/
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