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Saving the Amazing
No Way Home: The Decline of the World's Great Animal Migrations
David S. Wilcove. 2007. Island Press, Washington, D.C. 245 pp., hardbound. $24.95.
In the dusky light, it looked at first glance as if the pine trees wore fall-colored leaves, not needles. A closer look revealed thousands of black-and-orange monarchs blanketing the trees' branches. Yes, thousands—2,000 was the expert estimate—of butterflies cloaked three or four small pines as a few latecomers fluttered about looking for a berth. Spectacular, especially considering the trees were basically in a suburban backyard.
The next day they were gone, continuing a journey that would take the survivors to a few patches of firs in Mexico, thousands of miles away. Later, from the deck of the Cape May-Lewes Ferry, I spotted some brave butterflies crossing the open water of the Delaware Bay, an oddly moving experience.
It was mid-October in Cape May, New Jersey, a migration watcher's mecca. People flock to this peninsula that juts into the Delaware Bay to immerse themselves in the surge of birds and butterflies that break their journey south here. Hawk watchers scan the sky from a comfortable deck at Cape May Point State Park and count hundreds of soaring raptors a day. Other birders take to field and forest looking and listening for some of the millions of small warblers, tanagers, and swallows that pass through here. Clouds of monarchs feeding on blossoming goldenrod are easier to see. So too are dashing green darners, large dragonflies that have been sighted in the hundreds of thousands here. Bottlenose dolphins may be visible from the beach, lazily swimming toward warmer southern waters.
If you live anywhere nearby and have never made the pilgrimage to Cape May, now's the time, and be sure to take the kids. Because, as David S. Wilcove relates in No Way Home, great animal migrations are disappearing. Some North American ones are already gone: Miles-long flocks of passenger pigeons no longer blot out the sun, bison no longer roar across the plains between winter and summer ranges, and Atlantic salmon intent on spawning no longer clog East Coast rivers.
Wilcove explores these tragedies and others in the making. As the work of the Smithsonian National Zoo's Migratory Bird Center attests, Neotropical migrants like the warblers that pass through Cape May are in trouble. They are beset by habitat loss and fragmentation on their northern breeding and southern wintering grounds as well as at rest and refueling spots in between. Old World songbirds migrating between Europe and Africa face a different threat: Hunters shoot and eat huge numbers of them both north and south of the Mediterranean.
The African wildebeest migration between the Serengeti and the Maasai Mara is among the strongest of remaining mammal migrations. It still involves a million animals and most of their range is contained within protected areas. But farms and settlements are crowding the edges of these reserves, leaving no room for changes in migratory routes that are all but inevitable in the future. However, in South Africa, the migration of springbok, which once rivaled that of wildbeests in scale, is gone even though, like American bison, springbok survive. Wilcove makes the crucial point: "What is gone 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 forage."
Wilcove reports on the peripatetic lives of these and many other species, from right whales and sea turtles to locusts and horseshoe crabs. He reviews what scientists have learned about how some of these animals accomplish such amazing feats of navigation and endurance, and how much remains to be learned. No one knows, for instance, where green darners go for the winter or how a female loggerhead turtle finds its natal beach to lay eggs—25 or 35 years after it was last there as a day-old hatchling!
He also explores the havoc climate change may wreak on migratory patterns. Already there is evidence of timing mismatches between the birds' arrival on breeding grounds, which is cued to changes in day length, and the emergence of insect prey, which is dictated by temperature. For example, pied flycatchers have declined by about 90 percent over the past 20 years in the Netherlands because warming temperatures mean that the caterpillars they relied on to feed their nestlings are peaking too soon. Other dislocations are likely in the future. Where, for instance, will sea turtles lay their eggs when rising sea levels inundate their natal beaches?
Wilcove suggests "the hopeful possibility that ongoing efforts to address global climate change will spawn agreements and partnerships than can serve as models for addressing the plight of migratory animals." This is the only way that such species, many of which move in and out of the jurisdictions of dozens of countries and the phenomena of their migratory lives, will be saved. That said, I suggest not waiting too long to see some of these spectacles for yourself.
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