fb-pixel Skip to main content

The frogs have gone a courtin’

A wood frog found in Dracut. The males make all the noise, trying to attract females.Tim Beaulieu

Walking along a trail in the Middlesex Fells in late March, I found the sound of speeding traffic from nearby Interstate 93 deafening. As I got deeper into the woods, the noise of passing cars and trucks started to fade.

In the distance I heard another sound. Frogs. Hundreds of them, calling in a loud chorus.

I followed the sound about a quarter mile to its source: a large vernal pool about half an acre in size. Now it was the frogs that were deafening, drowning out the sound of the distant traffic. The high-pitched whistles of spring peepers dominated, followed by a background chorus of wood frogs with their duck-like quacking, and the occasional trill of gray treefrogs.


The first warm day of spring and a light rain the night before had coaxed the noisy amphibians from their winter dormancy and drawn them to this vernal pool to breed.

The males make all the noise, trying to attract females to mate with them. The pools are the center of activity for both frogs and salamanders for several weeks before the amphibians disperse back into the surrounding forest, leaving the fate of their eggs and offspring to the forces of chance and nature.

A vernal pool in Dracut.Tim Beaulieu

These small, temporary woodland ponds fill with water this time of year from spring rains and snowmelt, but usually dry out by late summer. This is important to animals that breed and live in vernal pools, because if the pools didn’t dry out, they would likely have fish in them, and the fish would eat the frogs and salamanders during breeding season, as well as their eggs and larvae.

But the fact that the pools dry out also presents vernal pool organisms with a real challenge, Matt Burne, biologist and vice president of the Vernal Pool Association, said in an e-mail.


“The frog tadpoles and salamander larvae are racing against the drying of the pool.”

Racing to metamorphose — develop into frogs and salamanders — before the pools dry out, or they’ll die.

For that reason, vernal pool species have adapted to starting their breeding as early as possible in the spring, Burne said. The first amphibian migrations begin with the very earliest spring rains, when temperatures are hovering just above 40 degrees, generally between March 15 and April 15 in eastern Massachusetts.

Underwater photo of wood frog egg masses in a vernal pool in Dracut.Tim Beaulieu

“Vernal pools are important because they are the only places [where] a number of species are able to successfully breed,” said Burne. “There are frogs, salamanders, and invertebrate species that have adapted specifically to the conditions that are unique to vernal pools, and their life history strategies make them entirely dependent on vernal pools.”

Vernal pools are also home to a number of rare species, such as blue-spotted, Jefferson, and marbled salamanders, Burne added.

Organisms that are dependent on vernal pools are known as obligate vernal pool species, and include animals such as spotted salamanders, wood frogs, and fairy shrimp, according to the Vernal Pool Association website.

Aside from providing breeding sites for numerous species of amphibians and invertebrates, Burne said vernal pool organisms are also an important part of the forest food web that other animals depend on to survive.

For example, some turtle species, such as spotted and Blanding’s turtles, feed on frog and salamander eggs, and snakes like garter and ribbon snakes will eat adult frogs and toads, as well as tadpoles.


A spotted salamander moves through shallow water during its annual breeding activity at a vernal pool in Stoneham.Matt Burne/Vernal Pool Association/Vernal Pool Association

Burne said vernal pools have been recognized as an important wildlife habitat resource in Massachusetts for several decades, and were provided protection under the Wetlands Protection Act regulations in 1988.

He added that vernal pools have since received additional protection under provisions of the federal Clean Water Act, septic system siting regulations, and the Forest Cutting Practices Act regulations. Many cities and towns also have wetland bylaws that protect vernal pools.

The Vernal Pool Association says certification of vernal pools is the procedure by which citizens can document the presence of one in Massachusetts, and helps begin the process of protection.

The upland habitat surrounding vernal pools is where vernal pool amphibians live when they’re not breeding, and is thus important for conservation as well.

The Vernal Pool Association says vernal pool certification requires photographs of the vernal pool, photographs of vernal pool organisms such as wood frogs, spotted salamanders, or fairy shrimp, or photos of egg masses of wood frogs or salamanders, as well as a map with the location of the vernal pool, and a completed observation form.

Burne emphasized that it is important to get landowner permission before exploring or certifying a vernal pool.

Documentation material — Guidelines for the Certification of Vernal Pool Habitat — should be submitted to MassWildlife’s Natural Heritage & Endangered Species Program, which then certifies the vernal pool.

Matt Burne (left) and Leo Kenney, co-founders of the Vernal Pool Association, visited a vernal pool on Long Island, N.Y. Vernal Pool Association

Don Lyman is a biologist, freelance science journalist, and hospital pharmacist who lives north of Boston. Send your questions about nature and wildlife in the suburbs to donlymannature@gmail.com.