The Great Moccasin Migration (continued)

Bluffs of 'ledgy character'.

Young Cottonmouth

Newborn Timber Rattlers.

Photo courtesy of Carl Hess.

By the middle of October, the snake migration is in full swing. Snakes of all kinds are heading for the bluffs by the hundreds during the day. Low temperatures, cloudy days or even cold rains do not stop them now. They are moving, racing against the changing season. For some, it is a matter of moving a few hundred feet; for other snakes, it may be a journey of several miles.

Not all snakes will immediately tuck themselves away after reaching their den site. On sunny October afternoons, snakes often can be seen basking out on rock ledges. By the end of October, most of the bigger species of snakes have reached their dens. A few stragglers will continue to arrive for the next week or two, and by the end of November all are tucked away for the winter. Garter and Ribbon snakes are often active a few weeks longer than most other species; they are the first to emerge in the spring, and the last to go to bed in the fall.

In early April, the sun's warmth penetrates into the dens enough to rouse the serpents within. April weather is a fickle thing, so the snakes may stay around the den site for a week or more, soaking up the sun's rays and retreating back into the cracks and crevices at night.  As the weather gets warmer, the Cottonmouths and other snakes return to their regular haunts and begin searching for their first meal of the year.

The den sites are much more than just a place to wait out the winter months. Gravid female Cottonmouths and Timber Rattlesnakes return to the den site in midsummer. The den site affords a secure location to give birth, and allows the females a better opportunity to bask for hours on end and raise their body temperature, as is necessary for the development of the young. Returning to the den also probably allows the young serpents to imprint on the den site, so that they can find it again in the fall.