|Photo Courtesy Zack West|
I saw a striped snake run into the water, and he lay on the bottom, apparently without inconvenience, as long as I stayed there, or more than a quarter of an hour; perhaps because he had not yet fairly come out of the torpid state. It appeared to me that for a like reason men remain in their present low and primitive condition; but if they should feel the influence of the spring of springs arousing them, they would of necessity rise to a higher and more ethereal life.
—Henry David Thoreau, Walden
A Cottonmouth Year
The seasons of a Georgia swamp can seem virtually nonexistent. If visited at any point from April to October, the untrained eye may discern no changes. The days are long and hot, and the entire active season seems to be one long summer—the genuine, buoyant spring and crisp autumn inexplicably missing. Compared to places farther north, seasonal changes take place at a leisurely pace, but upon closer inspection, and after achieving a more intimate familiarity, one realizes that anywhere you go on the planet—owing to its slight tilt toward the sun—there are always constant and sprinting upheavals, eruptions, and cycles. To get a feel for seasonal changes in Georgia, you have to practically get down on your hands and knees and crawl face-first through the rich muck, looking down into its swirling clay waters at least three or four times a week. Then you understand that the place does have seasons, and contained within that languid summer there are in fact the hurried activities of a thousand creatures contributing to the year’s changes. Cynics might instead categorize the seasons of Georgia solely in terms of its biting insects: winter is sand fly season, spring is mosquito season, changing to deer fly season, gnat season, and so forth. But instead I focus on the more abundant species that pack their activities into the long southern summertime, resulting in—for those with the patience to observe it—a net gain in seasonal activity.
I got to know these seasons well when I disappeared into a Georgia swamp for nearly a decade studying its snakes. I anticipated the emergence of snakes with as much esteem as singing frogs, blooming wildflowers, and arriving birds. I occasionally returned to civilization for dinner and a movie, for classes and graduations, for birthday parties and work. But those years in my memory are now an amalgam of yellow-green summers catching cottonmouths.
|Photo Courtesy Noah Fields|
For a few weeks, dozens of cottonmouths can be found near their wintering sites basking before descending into the floodplains to begin hunting. In April, before a riot of yellow-green vegetation fills the landscape, equal numbers of cottonmouths can be found basking as those lying next to narrow waterways, with their heads and necks cocked and aimed, ready to ambush prey. They are hungry after their winter slumber.
Then the trees leaf out, their hundreds of big trunks acting like a thousand straws sucking down the winter water table. The water sinks by at least 2 feet, and archipelagos, peninsulas, and a network of channels appear from the yellow water, forming a perfect maze of hunting edges for cottonmouths. For the next three months, the swamp is the setting for biological dramas rivaling those of the African savannah. Cottonmouths are a constant hazard for anything in the swamp smaller than a raccoon. Frogs, fish, birds, rodents, snakes, crawdads, and numerous other creatures live in perpetual anxiety that the next root they encounter may in fact be a cleverly disguised snake. Along the quagmire of cutoff channels, oxbows, sloughs, and beaver projects, dozens of cottonmouths are propped along the edge of the water, patiently waiting.
The hot days pass slowly, and you’ll be tempted to think that time has arrested, that the year has stalled in a long, humid purgatory of summer. Red-eyed vireos sing a drawling, repetitive warble from the treetops. Acadian flycatchers call abruptly from the hot, green gloom under the canopy, as if cursing the heat. Cottonmouths soon pile atop driftwood and hummocks, basking half in the filtered dark green, half out in the dappled summer sun. Such snakes have a lump in their belly, and are basking to quickly digest their meal before returning to the hunt.
Late summer—the breeding and birthing season—is the most mysterious and exciting time for observing cottonmouths. Half the females each year will give birth, and half are available for mating and will give birth the next year. The snakes seem to disappear. Many are likely under cover and up to sexual deeds. From July to September, you are equally likely to find a hunting cottonmouth as you are to suddenly stumble upon a quartet of plump, pregnant females basking atop an upturned umbrella of windthrown roots. Or you may turn the corner of a swamp channel and suddenly discover a female snake half out of her old skin—as if undressing—attended by a male lustfully nudging her back with his snout, passionately darting his tongue along her sweet, musky back.
Late summer progresses to a brief autumn, when the oppressive summer humidity at last yields to a mercifully crisp, dry heat. Nights cool off, and one by one the annual vegetation finishes, producing fruit, some edible to man, some only edible to rodents and sparrows. Cottonmouths become scarce. Females give birth to a small litter of colorful, yellow-tipped babies on hummocks during the first week of September and stay with them—perhaps to defend them—until their first shed a week later. As the first frost threatens, the snakes make their way back to winter dens, often to the same stump hole or granite outcrop used the previous year. In November, the sandhill cranes pass again—their fluting cries whispering down from the heights—and the snakes have assumed the same temperature as their winter quarters, reducing their heart rate to perhaps one beat every few hours, just to keep the blood going.
Winters are a short and rather exciting time in a Georgia swamp, and only a few days pass when no plant or animal activity occurs. All the knotweeds and sunflowers that stood head-high in the marshes during the summer now lay pushed down like a tangled mat, making a perfect home and providing food for swamp sparrows and orange-crowned warblers. The woods provide gleanings for small flocks of titmice, chickadees, nuthatches, and kinglets. Solo hermit thrushes and mobs of waxwings search for every last late-summer fruit. The sap never stops flowing down here, so sapsuckers hammer away at perfectly round sap wells all winter long. The cottonmouths stay in their holes and sleep.
It’s difficult to develop a detailed impression of the annual cycle of snakes. You need a decent-sized population so that you can reliably encounter individuals almost every time you go out to look. For snakes this is difficult. Either the numbers are too low and dispersed, so that discerning annual patterns takes years of study, or the snakes are only available for a short time period, so a wider seasonal picture is elusive. For these reasons, we know little about the seasonal activity patterns of such snakes as long-nosed snakes, which are fairly common but widely dispersed across the western deserts. We even have an incomplete picture of the well-studied common gartersnake, since they are abundant near their hibernation dens during spring emergence, but then disperse widely into the surrounding habitats for the rest of the year. By comparing numbers of snakes encountered seasonally across decades, we can piece together general seasonal patterns for many species. Radiotelemetry studies have given us excellent insights into the seasonal activities of larger snakes. But for most species, especially some of the interesting small ones, we have only vague notions of their seasonal patterns.