Vernal Pools Along the Trails

A vernal pool is a body of water that tends to dry up in the summer, doesn't have any fish, and supports certain species of wildlife that can't live or breed any place else.   Spotted salamanders, wood frogs and fairy shrimp are typical inhabitants of a vernal pool.  "Vernal" means spring, so it's really a "Spring Pool."  The photo at left is a spotted salamander larvae from Dominick Trail's "J Pond".  The photo at the lower right is a woodfrog tadpole from Nell's Rock Vernal Pool.

Vernal pools in Connecticut are just beginning to be studied, so no one really has a good grasp of what's out there. Every pool is different.  One pool may look promising but be nearly devoid of life, while a tiny mudhole may be filled with salamander eggs each spring.   Vernal pools make great classroom study because they are very visual and change dramatically with the seasons. Also, school research can generate useful data for state researchers.   Kids are usually more interested science projects when there is some valid reason to do the project, other than learning.

The absence of fish is very important when it comes to vernal pools.  Fish eat amphibians and their eggs, as well as various other types of water critters. Certain species cannot survive in the presence of fish and must therefore live or breed in a vernal pool.

The spotted salamander is a prime example. During most of the year, the salamander lives in moist woods buried in leaves.  But in the late winter or early spring, it is time to breed, and the males journey to a suitable vernal pool where they lay spermatophor on the bottom of the pond.  This pool may be far away; thousands of yards even. Then, during the first warm, rainy night of the season, the females embark on a similar journey to the same pools.  On this night, salamanders and frogs can be seen alongside the road from your car, and many are run over.  On Buddington Street I once saw about 50 dead salamanders and frogs within the space of about 100 yards near a large wetland.

Spotted turtles, a relatively rare type of turtle, migrate between local vernal pools, ditches and marshes.  In the spring they hunt the vernal pools for amphibian eggs.   In one tiny pond, from the trail, I watched a spotted turtle feasting on salamander eggs and hardly taking note of me.

Spotted salamanders and spotted turtles are easy to identify because they have bright yellow spots.  Wood frogs are small brownish frog which are difficult to see, but easy to hear.  In early spring they "quack" like a subdued duck.

In May, tadpoles emerge from toad eggs.  Since the puddle is only a few inches deep, they are easy to see, and a good attraction for children.   Please don't take any home. The tadpoles are dark black with big heads, while the salamander larvae are difficult to see since they are nearly translucent and very secretive.

Oak Valley Trail also has some vernal pools.  These are located on the old Bridgeport Hydraulic Company access road which starts on Rt. 108, goes into the woods, then comes back out along the powerlines.  These are deep spots in the road caused by tire ruts.  I've seen salamander eggs in at least three different puddles.

One fallacy that many wetland commission members believe throughout the country is that if you save the wetland, you have saved the species that use the wetland.  This is far from the truth, since many species only use the vernal pool for only a part of their life cycle.  Salamanders, for example, may live a half a mile away from the pond where they breed. If all upland areas around a vernal pool are developed, then the vernal pool animals will have someplace to breed, but no place to live.

The first type of wetland to be filled in by a developer is usually a "pocket" wetland.  Conventional wisdom has it that pocket wetlands have little value compared to larger wetlands.  In terms of biological production, however, a worthless pocket wetland might actually be very productive if it is a vernal pool.  This is one reason vernal pools are being studied in Connecticut. Not, however, that not every pocket wetland or puddle is a vernal pool.

Links: The Vernal Pool is an excellent web site created by the Vernal Pool Association of Reading Memorial High School in Massachusetts.  This site even has recordings of frog songs. They also put out a high quality guide for science teachers who would like to use vernal pools as a teaching tool.   I have an extra copy if an organization or teacher is interested.