Illustration by Adelaide Tyrol
I stood still as the weasel rippled, white and lustrous, through the stone wall. Six feet away, a deer mouse whose footfalls must have aroused the weasel, cowered against a tussock of grass. Suddenly the mouse burst to the right, then froze. Stung by the sound, the weasel hit the ground in a dead run. She held the mouse’s convoluted trail with her nose to the earth like a bloodhound, twice passing within inches of the mouse itself. But the mouse never flinched, and the weasel pressed on.
As the weasel finally closed in, the mouse bolted. Simultaneously, the weasel screeched and continued the pursuit, a tiny warrior with inexhaustible concentration. They darted across a mat of leaves, across a shag of fern, along a length of fallen elm limb. Both animals merged in a blur, the weasel furiously kicking and scratching and wrapping snakelike around the helpless mouse. When teeth met skull, all struggling ceased, and the weasel, with prey in mouth, disappeared back into the stone wall.
There are three weasel species in North America, two of which live hereabouts – the long-tailed, and the smaller short-tailed, or ermine. Collectively, they are quintessential mouse predators, sometimes following their prey into rural homes. I have live-trapped weasels behind a refrigerator in Norwich, Vermont, a stove in West Hartford, Vermont, and a furnace in Enfield, New Hampshire. In St. Johnsbury, Vermont, during the winter of 1987, several residents reported ermines in their homes. The fall of 1985 had produced a bumper crop of acorns and beechnuts and seeds. And after the high production of nutritious food, there followed a high production of nutritious mice. When the mouse population is up, more weasels survive the winter. Since a weasel can go anywhere a mouse can go, if snow forces mice inside, hungry weasels will follow.
One St. Johnsbury man caught an ermine in his living room and released it on the hill behind his house. The next night it was back. He reset the trap, and re-caught the weasel. This happened again and again. Eventually, he drove the weasel six miles away and released it. That night, the man again caught a weasel. He was sure it was the same one he had released. Of course no one else believed him – a small mammal only twelve inches long surely cannot cover six miles in a single night, past a corner of St. Johnsbury, past owls and cats and fishers (which eat weasels), and past cars (which flatten them). The man was not convinced, so the next night he caught the weasel and marked it with a spot of green nail polish and again released it six miles from home. In the morning he checked his trap and found a weasel – ermine white with a black-tipped tail, and a green spot on its rump. Finally he drove the weasel twelve miles away and set it free. Although the record for the longest distance traveled by a short-tailed weasel is 21.6 miles, that record trip required seven months. The St. Johnsbury weasel did not return.
Of the three species of North American weasels, the long-tailed is the largest. Males are 18 inches long, including a six-and-a-half-inch tail, and weigh about eight ounces. Females are four inches shorter and less than half the weight. Besides leopards in the Old World, mountain lions in the New World, and man in both worlds, long-tailed weasels have the most extensive north-south distribution of any wild mammal. From southern Canada to Peru, they pursue rats, mice, squirrels, gophers, rabbits, and sometimes day-old piglets.
Short-tailed weasels, which are much more common in our area, are circumpolar, ranging throughout northern Eurasia, where they’re called stoats, and Canada, south into the northern tier states, and west into the mountains. In both species of weasel, decreasing daylight triggers the autumn molt. The timing, however, is seldom precise and varies between species, within species, and even from year to year for the same individual. As nights grow longer, days shorter, and the maples begin to blush, the diminished light falling on a weasel’s eyes cause the pituitary gland – the body’s master chemist – to signal the pineal gland. In most northern weasels, the pineal gland secrets melatonin, which alerts the central nervous system to stop the production of melanin, a dark pigment found in hair follicles. Thus, new hairs turn white.
I stood by the stone wall in the moonlight and squeaked for the weasel, hoping it would put the mouse aside and investigate the new sound, for weasels are intensely curious. This weasel never fell for my ruse – it had already left the area. A neat set of paired footprints showed that it had bounded away, the mouse in its mouth scraping the snow on either side of the weasel’s head.
Ted Levin is a naturalist and freelance writer living in Thetford Center, VT.