The Decline of
the World's Great Animal Migrations

By David S. Wilcove

Island Press.

244 pp. $24.95

Reviewed by

Sandy Bauers

Inquirer Staff Writer

Deep in South Africa, inside a small national park - all of 14 square miles and enclosed by a chain-link fence - are 200 purplish-brown antelopes with sinuous horns. They are bontebok, the last remnants of the great herds that roamed the grasslands more than 200 years ago.

Protected from predators and watched over by biologists - indeed, the herd has to be culled from time to time - they are nevertheless little more than an oddity, closer to a zoo species than something wild, vibrant.

And they are, perhaps, a cautionary tale for the springbok, another South African antelope. Once, millions migrated across the Karoo shrublands, so numerous they shook the earth and trampled each other in headlong rushes.

Then settlers fenced the rangeland and hunted the antelope. Their cattle may have brought diseases.

Even now, the springbok is not endangered. But that's not the point.

"What is gone," Princeton University's David S. Wilcove writes in a startling and imaginative new wildlife book, "is not the species but the phenomenon of the species, the spectacle of hundreds of thousands of springbok marching across the Karoo desert, kicking up great clouds of dust, as they wander in search of forest."

At any hour of any day in any season, wildlife somewhere is on the move - "flying, walking, crawling, swimming or slithering from one destination to another."

Butterflies flap through Cape May headed for Mexico. Sea turtles swim mile after mile across the Pacific.

Some align themselves along magnetic fields. Others use visual landmarks. Salmon may locate their home waters by smell.

For thousands upon thousands of years, the journey has been arduous enough. Now, they face man-made threats as well: habitat destruction, human-created obstacles, overexploitation, and climate change.

The quadruple whammy has been devastating. For instance, researchers who viewed images from Texas and Louisiana radar stations, which detect the clouds of approaching wildlife, noted a 50 percent drop in migratory birds from the mid-'60s to the late-'80s.

It's pretty much all bad news, and the effect is cascading.

Above all is the "specter," as Wilcove puts it, of climate change. Global warming has the potential to "decouple" wildlife from the resources it needs.

Consider warblers that nest in deciduous forests in Minnesota. Their arrival in spring is timed to the emergence of tree-eating caterpillars, which the birds then feast on. It's a system in balance.

But if, to determine when to return from their wintering grounds, the birds cue on the hours of sunlight in a day (unaffected by climate change), yet the caterpillars cue on temperature (which is slowly rising), the birds may miss dinner; the caterpillars will destroy the trees. And so on.

The irony, Wilcove notes, is that "just as the phenomenon of migration is slipping away, we are entering a golden age for studying it."

Technology has helped. Fellow Princeton researcher Martin Wikelski has figured out how to affix tiny radio tags to something as small as a dragonfly to try to discover why it migrates, how it migrates and - this is still a mystery - where on Earth it goes.

Wilcove, a professor of ecology, evolutionary biology and public affairs, writes with a sense of drama, passion and awe for the incredible treks many animals make.

He gives readers a front-row seat to migrations over land, through the sea and in the air. We learn about bison, wildebeest, whales and shorebirds.

The North Atlantic right whale, one of the first species to be protected under the U.S. Endangered Species act, has become an "urban whale," he says. It has "the misfortune to migrate along one of the busiest coastal transportation routes in the world."

For many species, "a life history strategy that works brilliantly in a preindustrial world can be a major liability in a world dominated by people."

Wilcove explains things clearly - and without sugar-coating.

Many wildlife reports and publications end with a call to arms so predictable that you can almost script it ahead of time. It goes something like this: Yes, things are dire. But if we act quickly and decisively, we can save the . . . whatever.

Wilcove offers no such glib reassurances.

"There are, unfortunately, no easy solutions to this dilemma," he writes. "No obvious ways to balance the urgent needs of the present with what are likely to be equally urgent needs in the future."

That, perhaps, is more frightening than anything.