February Nature Almanac
• Candlemas on Feb. 2 honors the strengthening light and the stirrings of passion and new growth. Throughout the Celtic world, candles are lit to celebrate the return of the sun.
• Easter daisies, creeping mahonia, filaree and spring beauties bloom if the weather cooperates.
• Great-horned owls continue to "sing" duets and nest. You can tell the sexes apart because the female sings more notes at a higher pitch.
• Mountain bluebirds usually arrive by late February. A few, however, overwinter, and sometimes we get early birds. Two were spotted west of Hygiene on Jan. 2. Before heading to the mountains to nest, bluebirds form large flocks searching for insects.
Sometimes when you're all alone in a snowy landscape, a magical encounter occurs. Once, an ermine — white as winter, red with blood — popped up from the carcass of an elk. Loathe to abandon such a sumptuous feast, the weasel continued to pop up and down while keeping a wary eye on the intruder.
Weasels have streaked in front of us as we skied up a trail, and they have chased pikas in and out of the talus above treeline as we stood mesmerized nearby. If you imitate their squeaking sound by kissing your hand, you may even entice them out from the rocks.
Two weasel species inhabit Boulder County: the long-tailed weasel (Mustela frenata) weighing only about 5 ounces and the smaller ermine or short-tailed weasel (M. erminea) weighing only 1 ½ ounces. The even tinier least weasel doesn't live in Colorado.
In summer, weasels sport rich brown coats with either creamy yellowish or orangy bellies (long-tailed weasels) or white bellies (short-tailed weasels, also called ermine). After the October molt, both species gradually become white except for the black tail tip. The beauty of their snow-white pelage sometimes dooms ermines to a future as a fur coat. Native Americans used ermine skins to decorate war bonnets and robes, and over 50,000 were used for King George VI's coronation in 1937.
Starting in March, the fur slowly reverts to brown. Southern weasels remain brown throughout the year, leading to the question: if climate change means less snow, will weasels and other creatures that rely on protective coloration continue to perform this legerdemain?
Weasels must consume one-third to one half their body weight each day because of their frenetic energy and their stream-lined shape that radiates body heat. In "Rocky Mountain Mammals," David Armstrong writes, "By reputation they are 'vicious,' but by nature they are merely hungry." The hungry mustelids pursue mice, voles, chipmunks and other small mammals, often heading down narrow burrows and following runways under the snowpack. Feisty weasels can even subdue larger prey, such as snowshoe hares
Sometimes weasels take over a burrow after eating the original owner. If you see dark, twisted scat containing bones or hair at a burrow entrance or notice a skunky scent, you may have found a weasel's domicile. Snug in her winter den, a female is probably pregnant as they undergo delayed implantation after mating in summer. Young are born in spring.
Fast-moving weasels arch their backs and move in looping bounds with hind feet nearly meeting forefeet, reminiscent of an inch-worm. Watch for their dumb-bell shaped prints that appear to wander haphazardly across the snow.
Long-tailed weasels are relatively common from tundra to forests to grasslands to stream corridors. Less common short-tailed weasels occur mostly in the mountains. The weasel family includes Northern river otters, almost extirpated by trappers but recently documented in the county and, we hope, making a comeback. Martens, minks, wolverines, fishers, skunks, badgers and black-footed ferrets are in the same family.
Ruth Carol Cushman and Stephen Jones are authors of "Wild Boulder County" and "The North American Prairie."