It’s early spring, round about mid-March, when, as the Earth makes its way around the Sun, those of us in the Northern Hemisphere notice we’re receiving more sunlight as each day passes. So many life forms begin to stir in nature now — from budding leaves of willows and sassafras to sprouting shoots in the warming ground. Everything seems to be coming to life.
As I walk along the edge of an abandoned bog in Brewster, the song of peepers prevails loudly in the twilight.
Some of the brown leaves of the oaks, tupelos, and maples that dropped during the fall and winter have settled on the edges of ponds and especially in the ditches surrounding the bog. The dead leaves absorb the spring sunlight, warming the water quickly and bringing out of winter dormancy organisms too small to notice on a casual walk. One must bend low or wet a knee to see the stirring life in these marginal realms. Daphnia, copepods, fairy shrimp, and insect larvae turn these shallow waters into a living soup.
I am looking for some of the larger inhabitants of these bogs or vernal pools — the amphibians, which, with some effort, are easy to observe, though I see no signs of spotted salamander eggs or wood frog eggs yet.
I listen first, trying to locate the chirping of male frogs calling to attract females but find that they stop when nearby movement is detected. Ah — patience. I wait for a nearby frog to resume single chirps. I shine my flashlight on the presumed location and there it is, an inch-long brown frog, throat expanded, singing.
For the patient and diligent naturalist, young or old, this may be a once-in-a-lifetime observation. Yet we are always surrounded by thousands of these tiny spring peepers. Perhaps by the time you read this you will have heard their nocturnal chorus for yourself.
The peepers have been hibernating under leaf litter all winter. Yes, only under the leaf litter, not the muddy, deep, weedy pond bottom where the larger bullfrogs and green frogs hibernate. During the coldest nights and days, this tiny frog may freeze. A sugary antifreeze, glucose, produced by the peeper’s liver, replaces the water around its cells, allowing these tiny amphibians to freeze and thaw several times over the winter months.
All the while, as I stand in the wet grasses, I hear the intermittent “quack” of another species, the wood frog. If you should decide to get nocturnal and go forth in the next few weeks to stand amid the deafening chorus of peepers, you’ll hear this strange other call and know it is the wood frog’s. The songs and calls of these two frog species will increase in volume with rising March and April temperatures.
The third amphibian I look for is the strikingly beautiful spotted salamander. Typically, it’s the first rainy night after the March full moon when they will emerge from their winter hibernation. The spotted salamander is also called the mole salamander because, except for during a week or so in the spring, its entire life is spent underground in darkness, often in the borrowed burrows of small mammals such as moles.
When the spotted salamanders emerge in spring, they mass to the same local bogs and vernal pools occupied by the frogs. They come to mate. Males drop little white sperm packets called spermatophores, which are about the size of a grain of rice, on the bottom of the grassy or leafy pools where the females will collect them. A male will sometimes lead a female to his own spermatophores in an attempt to outcompete others.
The females clutch these sperm packets into their specially evolved cloacas with graspers to tuck the spermatophores up into their bodies in a form of internal fertilization. A few days later, the females lay tennis-ball-size gelatinous masses of eggs, which often can be seen attached to submerged grasses or stems.
In some years, when the meteorological conditions are right, thousands of salamanders end their underground hibernations in just one or two wet nights and pour en masse into a preferred watery pool. To observe the whirling, swirling masses of amphibian bodies in the shallow breeding pools is not something one soon forgets — it’s a celebration of nature that the curious naturalist may look for year after year.
I’ve observed that the timing of the emergence of the new generation of amphibians depends on temperature. When spotted salamander eggs are first deposited, the water is between 30 and 40 degrees Fahrenheit. The time it takes for the eggs to hatch may range from three weeks to a month — or more when the spring is cool. The larval stage is tadpole-like, but by mid- to late summer, they’ll have developed into two-inch-long versions of the black and yellow adults.
Some of us have our own “hot spots” to return to each spring. I recommend the Buttonbush Trail at the Cape Cod National Seashore Visitors Center in Eastham. Just adjacent to the amphitheater, a boardwalk spans a pool, offering excellent views of breeding spotted salamanders. Now is the time to observe this — so get nocturnal one of these March evenings, or at least consider yourself prepared for next year.
