Earth Almanac: January/February 2006

Winter Yaps

The yips, yaps, and howls you hear now in and around deciduous woods almost anywhere in the United States—save the high plains, the northern Rockies, and the Pacific Northwest—are likely the vocalizations of gray foxes as they start breeding activity. Winter is a good time to observe them or follow their straight, catlike spoor, which is often marked with urine that smells like skunk musk. (If the scent marks aren't malodorous, you're following a red fox.) European colonials disapproved of the gray because, unlike the slightly larger and not closely related red, which they imported from Europe, it would not run for the hounds. Instead it would “go to ground” (that is, hide in burrows) or climb trees, digging into the bark with its semi-retractable claws. The virtual disappearance of grays from Canada in the 17th century coincided with the irruption of reds, but the two events may have been caused more by the conversion of woods to fields than by direct competition. Grays, which have now repopulated parts of southern Canada, owe their remarkable success to their adaptability and their catholic diet (they'll eat almost anything organic).

Fossil Fuel

Those ancient nonflowering tree-size plants that dominated Carboniferous swamp forests during the Age of Amphibians 360 million to 290 million years ago haven't all been converted to coal or oil. You can still find them in most of North America, and winter, when their evergreen stems stand out against the drabness of low, wet places, is the best time to look. They survive today as jointed and segmented, vertically ridged, bamboolike perennials called scouring rush. These relicts have miniaturized to a height of three to five feet; but like their progenitors, they reproduce by spores and spread by underground rhizomes. In fact, if you introduce scouring rush to your garden, it can quickly crowd out other plants, so keep its roots in clay pots. Scouring rush is so-named because of its high silica content, which made it useful to Indians and early settlers for polishing cooking vessels. It has also been used in shampoo, as an astringent for cuts, and as a control for ticks and fleas.

Hawk Feeders

If you feed birds in winter, you may attract wild guests you hadn't counted on, including those that eat the birds that eat the seed. Throughout the contiguous states the most prominent among these is the Cooper's hawk—a medium-size forest raptor with a long tail and stubby wings that pursues birds and small mammals through the woods at afterburner speed. Attesting to the peril of this lifestyle is a study revealing healed bone fractures in 23 percent of all Cooper's hawks examined. They will pounce catlike from high ambush sites on birds as big as starlings and doves, then ride them around the ground, blue-gray wings spread possessively, red eyes flashing. If you are feeding winter bluebirds, make sure to place the mealworm container far from any seed or cracked corn and, if possible, where it's protected by overhead cover. Cooper's hawks don't have long talons or large beaks, so they kill their prey by squeezing it or even drowning it, a process that may take 15 minutes. It's not an easy thing to watch, but if you can welcome Cooper's hawks to your backyard as heartily as you do songbirds, you have arrived as a naturalist.

Anole of a Different Color

On warm winter days, from Virginia to Florida and west to Oklahoma and Texas, green anoles come out to bask in the gentle sun, sometimes clinging to vertical surfaces with their adhesive footpads. They're related to iguanas, but because of their ability to change in seconds from green to various shades of brown, these long-snouted, hot-dog-size lizards are often mistaken for chameleons. In the green anole's case, however, color change is more about mood and temperature than camouflage. Baskers tend to be brown, a color that better absorbs sunlight, while fighting males are usually green. During displays of territoriality males unfurl a red or pink dewlap and start a series of head bobs and push-ups. If you don't find anoles during daylight, hunt for them at night on leaves, eaves, and branches. In the flashlight beam they'll glow a ghostly green or yellow-white.

Swelled Heads

On frigid winter nights in lakes and rivers through most of Alaska, Canada, our northern states, and corresponding latitudes in Eurasia, fearsome-looking creatures, some the size of a man's leg, ease up into the shallows. There they mix eggs and milt, writhing together in quivering spheres that may contain 100 individuals. They are known locally as “burbot,” “eelpout,” “lawyers,” or “cusk”—green, mottled, slimy freshwater cod with huge heads, snakelike bodies, and succulent flesh. People who pursue them with ice-fishing gear say the flavor rivals that of salmon, trout, or walleye. Like their saltwater cousins, which also spawn in winter, burbot have a single barbel hanging from the chin and two smaller ones protruding from each nostril. Some scientists believe the burbot's progenitors were trapped in freshwater when an ancient arm of the sea receded.

Silken Sleepers

If you live in the eastern states and share the habitat of white pine, a quest for pine-tube moths is an excellent excuse to get family members, especially kids, out into the winter woods. Now the larvae have pupated, and each is wrapped in a silk-lined sleeping bag comprised of as many as 20 needles that, as a caterpillar, it wove together. A caterpillar constructs a new tube after it has eaten the old one down to about an inch in length, so don't be discouraged if you encounter lots of empty tubes. Eventually, you'll find the three-eighths-inch pupa. Touch it, and it will wiggle slightly. In spring pupae emerge as small moths. Pine-tube moths do no real damage to white pines because the two species evolved together.