Great Migrations Deserve Protection, Say Experts

- Gone are the days when millions of passenger pigeons crossed North America in flocks a mile wide that took days to pass. No longer do multitudes of bison wend their way across the nation's prairies. Even migrating songbirds returning to summers in Europe and North America are less abundant today, birdwatchers say.

Such great migrations must be protected, researchers argue this week in the journal PLoS Biology, not just to save the species in question, but because the migrations themselves are ecologically important and spectacular to behold.

"We have to save these animals while they're still abundant," lead author David Wilcove of Princeton University in Princeton, N.J. told Discovery News. "It's when they're abundant that they are able to play their ecological role so well. It's also what makes migration so inspiring. It's not seeing a dozen cranes on the Platte River in Nebraska. It's seeing half a million."

Wilcove points out that migrating salmon grow in the oceans, and swim upriver to spawn and die. Their bodies carry nutrients from the ocean to the rivers. Salmon today deliver only 6 to 7 percent as much nitrogen and phosphorus from the ocean to Northwest rivers as they used to.

"Songbirds migrating north in the spring consume vast numbers of insects that might otherwise defoliate trees and crops," Wilcove added.

Focusing on conserving migrations as phenomena, rather than just protecting species, is a new approach to conservation, he said.

"It's saying something that's qualitatively different than what we've done before. The key ingredients to protecting migration are to be proactive -- to protect species while they're still common -- and to act cooperatively, because the administrative boundaries that mean a lot to us people mean nothing to these animals."

"We need to find ways to be proactive rather than reactive," agreed Julie Young of the Wildlife Conservation Society in Missoula, Mont.

Diminished migrations might not drive a species to extinction, but that doesn't mean everything is well, she said. "People can get kind of comfortable at how many caribou there are. If they lose one corridor, they might be OK for several years, but it might just take one bad winter or a drought."

Young is part of a project to study the migration of the Mongolian saiga, a goat-sized antelope with a distinctive nose bump. The saiga's numbers have dropped 95 percent in less than 20 years, primarily because of hunting, now outlawed.

Working with the Mongolian Academy of Sciences, Young's team tagged five female saiga and tracked their whereabouts every five hours for a year.

Their tracking identified critical bottlenecks in the migration paths of the saiga, where mountains or other features limit the paths the saiga can take. One of these bottlenecks is only about three miles wide. Such areas are critical targets for maintaining migration routes, because if the bottlenecks are cut off by human development, the saiga have no alternative path.

Young said local governments in Mongolia are eager to find ways to protect the saiga, and are working to find compromises that will maintain these routes.

Migratory bottlenecks are crucial spots to protect, but at least they provide a focused target for conservation. For more dispersed routes, like those used by songbirds, sustaining routes may be more difficult. "You really have to protect pockets of habitat all the way from the breeding grounds to the wintering grounds," Wilcove said.

"If we are able to protect the great migrations that exist, it will be because we've set up a network of protected areas and we have learned to use the land and waters in sustainable ways across all sorts of international boundaries," he said. "And that will essentially mean that we have gone a long way toward protecting all of Earth's biodiversity."