Earth Almanac: November/December 2001

 Alien Beauty

The invasive, exotic plants we often call "weeds" should be controlled where possible. But you need only detest what they do to the rest of our biota and the stupidity and carelessness that displaced them from their native soil. It’s okay to appreciate weeds as individuals. Consider the common teasel of Eurasia, so named because it was long used to card, or "tease," wool. Teasel, apparently introduced to the New World in the 18th century, is now extant in the eastern half of the United States and spreading via our interstate highway system. By late fall the gaudy, purple flower heads, which were worn by medieval knights, have withered, and their egg-shaped skeletons, with their intricate geometric spines and markings, stand against the gales of November. Unless crushed by snow or cut for dried-flower arrangements, they will keep standing all winter.

Beshrewed

What’s that quick, beady-eyed little rodent with the sharp face, popping up and giving you the once-over? It’s a shrew--not a rodent at all, but an insectivore. Shrews, the smallest and among the most common mammals in North America, abound throughout most of our nation, but rarely do we see them, because they spend so much time in tunnels made in the earth or snow by moles and voles. Late fall, before snow provides them with insulation, is the best time to see most of the continent’s 20 species; that’s when they must hunt even more frantically than usual to maintain their metabolisms. You’ll see dead shrews more frequently than live ones, for two main reasons: One, a predator has killed them, then been repulsed by their strong musk (obviously an inefficient defense mechanism but probably useful in marking territories); or two, they have suffered "cold starvation" by losing heat faster than they could generate it. One species, the short-tailed shrew, is venomous. With its red teeth it delivers nerve poison that can instantly paralyze an animal as much as 20 times its size. The poison, however, wears off quickly, so the short-tailed shrew has to eat its meal with great haste. Fortunately for the species, this is never a problem.

Finer Art

Autumn shows more subtle beauty after wild winds waste the golds and scarlets of October. On the first really cold night, when woodsmoke rises straight into a cloudless sky and the shadow part of the moon is lit by starlight and earthshine, hoarfrost will adorn grass and fading hardwood leaves. At first light it will dazzle you. Hoarfrost, white from air bubbles, and with etchings that resemble feathers, trees, ferns, or flowers, is an analogue of dew. But it is not frozen dew. Its intricate, interlocking crystals grow when water vapor turns directly to ice, skipping the liquid stage. There are two basic types of hoarfrost--the early variety you encounter now, and that which occurs more in midwinter and includes renderings on frozen streams and ponds.

Crow Time

When the yet-snowless woods are silent save for the rustle of southbound wings and brown leaves clutched by oak fingers, one tends to notice crows. Penciled on gray sky, strung out high and low, they scull purposely to and from roosts at dusk and dawn. Most will be American crows, our biggest crow, which are seen almost everywhere in the nation. Mark their comings and goings and you may discover their winter roost. One important clue: The ground beneath will be littered with regurgitated pellets of compacted fur, hide, and bone. The main criterion for a roost is shelter. It may be located in dense conifers, in thick hardwoods, or even in low brush or lakeside reeds. Where winters are mild, a roosting congregation may be enormous; as many as 200,000 birds once occupied just 20 acres in Arlington National Cemetery. When our economy was more agricultural, crows were regarded as the personification of evil. Not only did they steal our food, they insulted us in the process by perching on the arms of scarecrows. As recently as the 1930s we’d dynamite their winter roosts, killing thousands in a single detonation. Crows are better appreciated these days, in part because we compete less with them. But even when we persecuted crows, we admired them for qualities we saw in ourselves. American crows are aptly named. They belong in and to our land. They are loud, resourceful, durable, and adaptable. They live in wilderness and megalopolis, prospering with or without us. They are part of smoke-scented twilights and crisp, otherwise silent mornings, part of what we were, are, and hope to be.

Fish of Steel

Did you really see that flash deep in the silted, swollen flow? If you’re not sure, move upstream to the first falls. Never will you be quite ready for the silver fish that hurtles into the cold, wet air and hangs across black conifers or gray sky. It is a steelhead--the big, powerful, migratory strain of rainbow trout fresh from the North Pacific, or the Great Lakes, where it has been introduced. Toughest of all Pacific salmonids, the steelhead endures in dammed, dewatered rivers where our five West Coast salmon species are flickering out. Unlike Pacific salmon, steelhead don’t always die after spawning. Cut off from salt water by summer drought, they can survive in fresh water for a year, eating almost nothing. A few will make five spawning runs during their lifetime and attain weights approaching 50 pounds. One threat to self-sustaining steelhead populations is hatcheries, which take eggs early to fill available space, thereby selecting against fish that run later in the year and for ones that do well in crowded, shadeless conditions (in short, selecting for everything wild trout are not).

Decking the Desert

Not all of the arid land from western Arizona to Texas and northern Mexico qualifies as "desert," but throughout much of it you will encounter the desert Christmas cactus, a spindly, spiny shrub that grows to about three feet. During most of the year, even in spring, when it blooms in yellow-green flowers, it is a thoroughly unimpressive plant. But now its berries shine as scarlet as the tree ornaments for which the plant was named. On a bleak landscape in a drab season, the desert Christmas cactus gladdens the spirit of the lonely wayfarer.