Earth Almanac: March/April 2009

Vireo and Juliet 

From the northeast corner of British Columbia, east across Canada, and south through New England and the Appalachians, blue-headed vireos are courting. But for males, winning a mate only starts with filling the forest with a broken series of sweet, slurred whistled notes extolled by ornithologist Edward Forbush as “a charming cadence of the wooded wilderness.” The bigger the male’s territory, the better his chance of winning a female. He then must build her a “courtship nest,” presumably to demonstrate that he is capable of constructing the real item—a cup of down and bark, hung from a forked twig. If she approves, his work still is not finished, because he has to help her incubate three to five white, brown-spotted eggs, uncommon behavior for passerines. Only recently has the blue-headed vireo attained species status. Previously, it was considered part of the solitary vireo complex.

Hummer Pit Stops

In our desert Southwest, spectacular foot-long clusters of red blooms are hanging from the branch ends of the cactuslike ocotillo, a.k.a., “devil’s walking stick.” And just in time, because flights of northbound hummingbirds, one of the plant’s pollinators, are in desperate need of energy fixes. Few, if any, insects can reach the nectar, but carpenter bees “cheat” by cutting through the inch-long flowers. A prime ocotillo may be close to 200 years old and have 100 spiny stems rising from its base. For this plant, fall may come half a dozen times a year, when dry spells cause it to shed its leaves. They grow back fast after a rain. In addition to sustaining hummingbirds, the ocotillo is an important food source for mule deer, white-tailed deer, bighorn sheep, and antelope ground squirrels. The Apaches used the powdered roots to treat wounds. In frost-free parts of its range, ocotillo can be easily propagated by jamming cuttings into the ground.

Cheeky Chaps

The response most often elicited in humans by chipmunks is a smile. And none of North America’s 15 species brings more smiles than the smallest and most widely distributed—the perky, noisy, cocky least chipmunk. In our north-central and western states, least chipmunks are coming out of winter dormancy, pushing corn snow from the entrances of their cozy subterranean dens, and dashing around woods, pastures, and sagebrush deserts in mad mating chases. Least chipmunks announce their presence with monotonously repeated chips, and real or imagined danger with loud trills. A large least chipmunk might weigh two ounces, but what it lacks in size it makes up for in chutzpah. For instance, even as it jealously watches its own hoard, it will dash in and fill its cheek pouches from a neighbor’s seed cache or with food from your plate or even your fingers. In addition to vegetable matter, least chipmunks consume a good deal of meat, including adult and larval insects, bird eggs and hatchlings, and the young of small mammals.