Warblers at the Breakfast Table--in Spirit
The woods around home were quieter than they should have been this autumn. The whistles and chirps from gathering flocks of south-migrating songbirds were sparse. Maybe the Interior's wild summer weather did in the birds; local birdwatchers have commented on nests being rained out this year.
But maybe it's trouble at the other end of the line. Many of Alaska's summer songbirds spend their winters far south of the U.S. border, in countries where growing human populations and struggling economies have put terrific pressures on the birds' natural habitat. So whether it's real or illusory, temporary or permanent, the decline in songbird numbers and kinds has made me especially alert to news about what could affect Alaska's birds when they're not living in Alaska.
Would you believe--coffee?
That's a flippant synopsis of the conclusions of a serious study. Four years ago, Russell Greenberg of the Smithsonian Institution's Migratory Bird Center in Washington, D.C., sat down with some colleagues and pored over records of songbird numbers. They calculated that populations of North American birds that spend winters around the Caribbean and elsewhere in Latin American were declining by 1 percent every year.
They suspected habitat change was the chief culprit. Decade by decade, more and more of the hill forests favored by the birds have been cleared for agriculture. That the birds were surviving at all meant they had adapted at least partially to life with farmers. Greenberg's research team went to investigate how the songbirds were coping, and failing to cope.
They found that the birds don't see all farms as equal. Some methods of farming provide respectable amounts of shelter for both transient and resident birds. Traditionally, at least from the time when the Maya ruled in Middle America, certain crops have been cultivated in shaded plantations. These crops include cocoa and coffee, the chief legal cash crop in the region. The birds chose to live in the forested patches retained to shade the crops and in cultivated woodlands where trees like acacias were grown as woody crops.
During the past two years, the Smithsonian researchers counted more than 180 species of birds, both migrants and tropical residents such as toucans and parrots, on old-style shaded plantations in the Ocosingo area of the state of Chiapas in Mexico. The resident Maya farmers have preserved some of the only vestiges of the original forest for shading their small farms, and others have attempted to copy them by planting trees around their fields. The taller shade-giving trees also provide natural fertilizer through the mulch of their fallen leaves, and because many of them are nitrogen fixers, they absorb this essential nutrient directly from the air. Their roots keep soil from eroding, and they also shelter forest animals which play important roles in the farmers' diets.
It's reasonable to expect the birds that have adapted to this kind of agriculture would be the ones we know, since the farmers of Mayaland have employed shade growing for more than a thousand years. But now more coffee growers have turned to growing coffee without shade, and that is surely contributing to the songbird decline.
According to New Scientist magazine, which reported on Greenberg's work, coffee trees grown in full sun produce more coffee beans than do shaded trees, at least at first. But sun-grown coffee also requires more weeding, more fertilizing, and more pest controls. It also leads to more erosion and water pollution.
With these problems, but especially with the threat to birds in mind, Greenberg is now campaigning for a uniform labeling procedure so birdwatchers can identify and buy shade-grown coffee. (Most Western Hemisphere coffee consumed in the U.S. is still grown on shaded plantations, so bird lovers can imbibe relatively guilt-free, so far.) Starbucks, the Seattle-based gourmet coffee company, is at least considering his idea. The shade-grown coffee label may come to be a sign of life for Alaska's migrating songbirds.
