A Big Night for Migrating Amphibians

A “Big Night” out for most people involves getting dressed to the nines and indulging in an elaborate dinner, but for some adventurous environmentally conscious individuals, donning a reflective rain slicker and scanning the pavement along the roadside with a flashlight in hopes of finding migrating amphibians, can be equally satisfying.

When the overnight air temperature surpasses the forty degree mark, and the first torrential spring rain saturates the ground, the conditions are just right for a Big Night event. If you think you might enjoy playing the role of crossing guard to hundreds of slimy, wiggling salamanders and hopping tree frogs as they migrate from their semi-frozen earthen burrows to the vernal pools where they will mate, then you might want to join Tom Cleveland and his rarified crew who do just this.

During a recent spring rain storm, Cleveland and a band of ten volunteers spent the evening on Hosely Avenue in Branford picking up spotted salamanders and walking them from one side of the road to the other. The group was on a mission - to prevent the critters from becoming road kill! “Besides being a lot of fun, it’s the one time of year when you get a chance to see a very prehistoric, extremely unique form of life.” says Cleveland. His platoon, comprised of husbands and wives and youths between the ages of eight and fifteen, ushered ten of the nearly seven inch long, dark grey amphibians sporting dual head-to-tail rows of bright yellow spots, across the pavement during the two hour escapade.The rain fell lightly on this particular evening, and therefore the migration was correspondingly small. Cleveland notes he would like to have seen “water bouncing off the pavement in a torrential downpour” and then possibly the migration could have been ten folds larger. He notes that this spring has consisted of multiple smaller migrations and not the single massive movement that many people look forward to and have termed Big Night events. “When it has been really cold and dry, and then all of a sudden BAM it gets warmer or BAM it precipitates – then you get a really solid migration.”

The spotted salamander is one of four species of mole salamanders that live in Connecticut. This animal spends most of its life buried beneath leaf clutter, under logs or rocks, or living in subterranean burrows in hardwood forests. “They are pretty much out of sight most the year, except for when they migrate during this spring period.” Cleveland points out.

Getting trapped in cold or dry conditions will kill these tiny animals, so the amphibians need to make a calculated bet on when it is safe to make the trek to the vernal pools where they will converge and mate before returning to their underground dwellings. Migrations up to several thousand yards are not uncommon. “These creatures don’t move quickly at all. At a full gallop, they’re not going 1 mph!” says Cleveland, and that is why it is so important for people to assist the salamanders across streets where development has divided the woodlands.

Reproducing in vernal pools offers the gelatinous milky white egg masses, which the female salamanders have attached to submerged twigs, protection from fish that would otherwise devour the undeveloped young. Before the pools are sucked dry by the roots of surrounding trees, like millions of straws emptying a giant glass of lemonade on a summer day, the salamander larvae will hatch, feast on aquatic insects, and then retreat into the woods.

While the spotted salamander is making its travel plans, another spring-time amphibian is desperately trying to make its presence known. Often heard, but seldom seen, the Spring Peeper, a member of the Chorus Frogs, is one of the first creatures to emerge from the frozen ground and herald the call of spring with its song.A brazen young male will lead the night-time chorus. His shrill preeep will radiate among the trees and then suddenly the forest will explode with the raucous sounds of hundreds of tiny tree frogs following suit. The male frogs are in competition with one another and will preep faster and louder until the intensity of their high-pitched calls become deafening.

(salamander photo courtesy of Tom Cleveland)

Lady frogs are highly selective and choose their suitor by the quality of its call, so this contest is one of survival and not just bragging rights. As quickly as the symphony started, the forest will go silent, and the calls will stop just long enough for another frog to lead the chorus in new round.

Spring Peepers are tiny tree frogs that prefer to spend most of their life about three feet off the ground clinging by their adhesive toe pads to tree trunks and grasses alongside ponds and wetlands. Less than one inch in size, the gray-brown frog is well camouflaged. Should you come across a peeper, the large dark “X” on its back will be the key to its identification. High concentrations of glycerol in their body tissues allow peepers to survive sub-zero temperatures without damage, even though 35% of their bodily fluids have frozen solid. It is farmer’s lore that it is time to take down the maple syrup buckets once the peepers have thawed for their third time.

The diminutive frog’s powerful call comes from the vocal sac under its chin which gets pumped full of air until it is distended to a bubble rivaling the size of its entire body. By releasing a mighty burst of air, the frog disrupts the evening’s silence with its resonant preep.

Big Night events are becoming increasingly more common throughout the Northeast, as people become intrigued by these night-time exhibitionists. Cleveland, who serves as the Vice-President of the Branford Land Trust, has been observing and helping these fascinating amphibians for many years. Each time people encounter one of these frogs or salamanders he says “It reminds you of the magic that natural systems have to offer if you just slow down and look.”

While most of the salamander migrations have been completed for this year, there is still plenty of time to enjoy the call of the peepers.