May 9, 2010

In the frosty pre-dawn darkness, Bridget Stutchbury is slipping stealthily through the Pennsylvania woodlands, occasionally flashing a light to illuminate a landmark. She is trailing a philanderer, hoping to catch the hussy in the act. For two hours she tracks her target by sound and by radio — and she fails. The floozy demonstrates perfect chastity.

The philanderer is not a woman, but a bird, a female Acadian flycatcher, and Dr. Stutchbury is not a private eye, but an ornithologist who studies the social life of songbirds, including their sex lives. This is not leering voyeurism. Songbird populations are falling steeply, and to reverse the decline we need to understand not only the reasons for their decline, but also their requirements for successful reproduction.

Professor Stutchbury, who teaches at York University in Toronto, actually calls herself a “behavioural ecologist” or, more colloquially, a “bird detective.” That’s also the title of her newest book, and of the talk she’ll deliver at Dalhousie University Wednesday evening. She has spent her life studying songbirds in the wild, and her first book, Silence of the Songbirds, described what she had learned about them.

Silence of the Songbirds is an intensely readable book, a finalist for the Governor General’s literary award. But the story it tells is a sad one.

Songbirds are astonishing little creatures. Many of them winter in tropical forests from Central America to mid-South America, and breed in the Canadian north. They cross the Gulf of Mexico in a sustained 15 to 20-hour overnight flight that can cost them nearly half of their body weight. At the height of the migration season in April and May, US coastal radar stations pick up huge clouds of north-bound birds soon after sunset — as many as 50 million in a single night. In the early days of radar, before operators realized what was happening, they referred to these mysterious waves of aerial movement as “storms of angels.”

The destination of billions of these “neotropical migrants” is what Stutchbury calls “the biggest migratory bird nursery in the world,” the vast northern boreal forest that stretches across Canada from Newfoundland to the Yukon and Alaska. Here, in a few intense summer weeks, the birds find mates and build nests, conceive, hatch and nurture their young — and then fatten themselves again for the long trip south.

The birds are at risk in every part of this demanding life cycle. Fully half of them die in the course of every year’s migration, and the explosion of human populations has multiplied the hazards they confront. Their breeding grounds in the boreal forest are being chipped away by industry. The temperate forests of eastern North America once provided a vast leafy flyway from Canada to the Gulf of Mexico, but they have been reduced to fragments and the tropical forests are falling at a terrifying rate.

Lighted skyscrapers and transmission towers represent lethal obstacles to night-flying birds. Latin American farmers use staggering quantities of pesticide, with lethal effects on wintering birds. A Wisconsin study in the 1990s estimated that, in that state alone, domestic cats annually killed somewhere between 8 million and 217 million birds.

And all of this is in addition to natural predators like squirrels, raccoons, snakes and other birds.

Stutchbury notes that we can all help by behaving thoughtfully — keeping our cats indoors, drinking shade-grown organic coffee, eschewing pesticide-soaked produce, buying FSC-certified lumber and paper products, dousing office lights during migration season. Most of these are better choices anyway.

Meanwhile, the annual Breeding Birds Survey shows at least 18 species of migrant songbirds in serious decline. And if you think this has nothing to do with you, think again. The songbirds are an integral part of the web of life that sustains us all. The quality of our air, for instance, relies on healthy forests — and the trees rely on the songbirds to control their insects, pollinate their flowers and distribute their seeds and fruits.

But to value songbirds for their usefulness to humans is morally bankrupt. Songbirds are among nature’s most exquisite creations. If they don’t lift our hearts, if we can’t value them for themselves, then we have no right to share a planet with them.

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I interviewed Bridget Stutchbury for The Green Interview during her visit to Halifax. We’ll run the interview on the site later this year.