The Porcupine herd of caribou (named for the Porcupine River) in Alaska travel 1,800 miles (2,900 kilometers) throughout the year from feeding ground to breeding ground—one of the longest overland migrations in the world. But planned development to extract oil could block a portion of this great herd's annual trek.

The threat to caribou is just one of many detailed in the 2008-2009 edition of the Wildlife Conservation Society's (WCS) State of the Wild: A Global Portrait of Wildlife, Wildlands, and Oceans, which assesses "where we think we are and where we think we can be," says Steven Sanderson, WCS president and CEO.

Treks such as those done by the caribou every year are disappearing the world over and some have been lost: The big-nosed antelope (Saiga tatarica) of Asia no longer live in China, elephant travels in Africa have been curtailed, and the bison of North America no longer roam the vast interior plains. "Animals move between areas and back again," says biologist Joel Berger of the University of Montana–Missoula. "It's a survival strategy, whether it be wildebeest or caribou."

Even as humanity has spread to directly effect roughly 40 percent of the world's surface—and harness 50 percent of the world's photosynthesis for our own purposes—the "wild" still exists, according to Kent Redford, WCS vice president of conservation strategy. He alludes in particular to the 680,000 acres (275,185 hectares) in Chile's Tierra del Fuego islands gifted to WCS as "forever wild" by Goldman Sachs in September 2004. But the human relationship to such wild places and the creatures that inhabit them is fraught, whether that wildlife be the butterflies released at an American wedding or the sea turtles choking on plastic bags they take for jellyfish. "At best it is a prop," he says. "At worst, it is a design to be replicated."

This fraught relationship does not leave humanity untouched. In addition to the chemical legacy carried by modern people, the book focuses particularly on the growing threat of zoonoses—diseases that jump from animal to human—that can arise from the incursion of people on wild habitats: Of the 58 percent of human diseases caused by germs, 816 of 1,407 known human pathogens emerge from wild animal populations. For example, wild fruit bats are suspected* to be the reservoir where the Ebola virus waits for a chance to infect people. At the same time, human activities such as deforestation are creating more habitat in which the mosquitoes that spread malaria can thrive, according to environmental health scientist Jonathan Patz of the University of Wisconsin–Madison.

Veterinarians William Karesh, director of WCS's Wildlife Health Sciences, and Kristine Smith of the society's Field Veterinary Program argue that eliminating wildlife trade and focusing on controlling and eradicating the disease in poultry could prevent a future epidemic of the bird flu strain H5N1. The reverse—the spread of human diseases to animals—can be equally deadly: At least 5,000 western lowland gorillas have died from the Ebola virus.

There have been, however, some conservation successes. Though sturgeon, shad, the Atlantic salmon and other species that travel from sea to river and back again persist at less than 1 percent of their historic levels, dam removal in places like the Kennebec River in Maine has allowed some species to recover, notes biologist John Waldman of Queens College, The City University of New York. And the poisoning of vultures in Asia that threatened to wipe out the three scavenging bird species of the Indian subcontinent has been checked through a combination of replacement drugs in livestock and captive breeding efforts, says ornithologist Nancy Clum of WCS.

The book also contains essays from experts ranging from conservationist J. Michael Fay—who famously trekked across the Congo Basin to survey its ecological status—to oceanographer Les Watling of the University of Hawaii at Manoa writing of the critical need to protect remaining wild places in places such as the Central African Republic and the relatively unexplored deep sea. Recent surveys have found more than 2,300-year-old colony of deep-water black coral 1,480 feet (451 meters) below the surface off Oahu—and deep-sea fishing threatens the long-lived, slow-reproducing species that inhabit the sea bottom such as the Patagonian toothfish (better known as Chilean sea bass).

The book does not ignore the plight of humans forced to move or forgo their livelihoods to make way for protected wildlife areas. "Human welfare and conservation have become increasingly intertwined—politically, philosophically and practically—and ignoring human displacement undermines the moral basis for conservation," wrote political scientist Arun Agrawal of the University of Michigan at Ann Arbor and WCS's Kent Redford and Eva Fearn. "As a matter of both ethics and pragmatism, the conservation community must respond."

In addition to highlighting the victories and losses in conservation since 2006, when the last edition came out, the book includes 33 essays from experts, ranging from NASA climatologist James Hansen's thoughts on global warming to futurist Stephen Aldrich's musings on the potential for artificial life-forms.

State of the Wild is also a call to action in an era when 50 percent of the nearly 6,000 known frog species could go extinct in the next 50 years thanks to a combination of chytrid fungus disease, habitat destruction and global warming. "We don't collaborate enough," WCS's Sanderson said at a conference announcing the book today. "It's foolish to think one organization can do this by itself."

Editor's Note: This article originally stated that fruit bats are the reservoir of the Ebola virus. That has not yet been proved.