Earth Almanac: November/December 2008

Swan Song

Usually you hear them first—a flight call reminiscent of Canada goose music—and they will be far in front of the sound by the time it reaches you. Look up and you may see their V formation silhouetted against sun or moon, sometimes a mile high and, if there’s a strong north wind, moving at close to 100 miles per hour. They’re tundra swans migrating from their Arctic breeding grounds to winter on the interior West’s open water, in the Great Lake states, and along both coasts to southern California and South Carolina. We almost lost these birds to market hunting in the early 1900s, but they’ve rebounded so dramatically that some states now allow sport hunting. Part of the reason for the species’ success is its adaptability. For example, most of the eastern birds used to winter on Chesapeake Bay, but with increasing competition from alien mute swans, most now spend the cold months in coastal North Carolina. Historically, tundra swans ate mostly submerged vegetation, though with widespread wetlands destruction, many have moved inland to feed on grain crops.

Skunk Bear

In tundra and boreal forests of Europe, Russia, Siberia, and Alaska, and in the wild country of the western United States, most notably central Idaho, winter belongs to the wolverine. This, the largest and least-known member of the weasel family, rarely weighs more than 35 pounds, yet it is capable of running down and dispatching full-grown elk and mountain sheep. And it can dig through packed, icebound snow and gnaw through frozen carcasses and bones. Because of these adaptations it is often closely attended by foxes, which gorge on the leftovers. The wolverine marks trees in the fashion of bears, clawing and biting bark and perfuming trunks with powerful musk from its anal and ventral glands—behavior that has earned it the alternate name of “skunk bear.” So adept is it at avoiding traps and opening doors, windows, and even cans with its teeth that it has long been supposed to be in league with the devil.

Sleeping Beauties

Suspended batlike from twigs and fence rails east of the Rockies and camouflaged brown or green, black swallowtail butterflies are sleeping away the winter as cashew-shaped chrysalides. If you find one, touch it and it will sometimes wiggle its “tail.” Don’t be afraid to move it to your garden or doorstep, but keep it outside and don’t detach it; take the whole stick or, if possible, a splinter from the fence, and secure the butterfly above ground. In spring check it regularly. As the days lengthen it will turn translucent, and you’ll be able to see black, spotted wings. Any help you give the adult as it struggles from its confinement will abort the wing-hardening process.