The Value of Diversity

Park officials had long suspected that fishers were missing from the forest, but it wasn’t until 1998 that the species was officially designated as endangered in Washington State, after a careful scientific investigation failed to find any. That’s when wildlife experts decided it was time to take action. Over the next decade, park managers worked with the Washington Department of Fish and Wildlife to research and devise a restoration plan. The multi-person effort relied upon a careful understanding of the fisher’s attributes and its ecological role.

Fishers fall into a class of vertebrates called mammals, animals with mammary glands and a body covered with hair. Like many mammals, fishers are predators, hunting mostly other small and midsize mammals such as snowshoe hares, squirrels, mice, and beaver. With their keen sense of sight and smell, sharp teeth, and nonretractable claws, these nocturnal creatures are among the most effective predators on the ground and in trees.

Fishers themselves have few natural predators. They are occasionally killed by cougars, coyotes, and eagles, but the fishers’ biggest foes, by far, are humans. For hundreds of years, fur traders trapped and killed the animals for their soft pelts. By 1934, when the practice was outlawed, fishers had largely been hunted to extinction. Fishers were also an unintended target of a massive government-sponsored predator control program in the early 20th century intended to reduce the number of wolves, which posed a danger to livestock. Officials with the U.S. Forest Service set poisoned traps for wolves and in a matter of years slashed the wolf population in the lower 48 states to near zero. Meanwhile, unsuspecting fishers ate the same poison bait and also perished.

Because humans are largely responsible for the decline of the fisher in Washington, many conservationists believe it is our ethical duty to help undo that damage—restoring diversity for diversity’s sake, as it were. But there is a good ecological rationale for such action as well. “When you start getting up into the mammalian species, going up the phylogenetic tree,” says wildlife manager Happe, “there’s fewer species, but one animal has a big effect on the ecosystem.” That is especially true of predators, such as the fisher, that act as a natural population control on other species.

For example, in some parts of their range, fishers are one of the few natural predators of porcupines. A healthy fisher presence in a forest helps keep the porcupine population under control and prevents what would quickly become a prickly problem for the trees that the porcupines eat and the loggers who cut them for lumber. Restoring fishers to the ecosystem is therefore necessary to keep the natural web of the environment intact, and to preserve economic goods—lumber. “They fill that niche back up that nothing else can quite totally fill and restore some resilience to the ecosystem,” says Happe.

Exactly what effect the reintroduced fishers are having in Olympic, researchers can’t say for certain at this point. “I’m sure that it’s having repercussions in the ecosystem, it’s just that we can’t interview the squirrels and the rabbits to find out what they think of all this,” says Happe.

Restoration efforts such as these are guided by the scientific understanding that the healthiest, most stable ecosystems are ones that have abundant biodiversity. Predators, especially, play an important role in an ecosystem—something that conservation biologists have come to understand in the wake of wolf eradications. Wolves, for example, prey on elk—one of the only species that can do so. By keeping elk herds in check, wolves help keep trees from being overgrazed by the elk (see Chapter 21). When predators go missing, a whole cascade of disruptive effects can result. “When you take those species out, then it’s kind of like a tower of building blocks: you have less structure to keep your environment together,” says Happe.

With the return of the fisher, the only species that is still missing from Olympic is the gray wolf. There’s been talk of restoring wolves to Olympic—as has been done in other national parks, such as Yellowstone—but so far no definite plans have been made.

The restored fishers—90 so far—join a variety of other vertebrates living in Olympic, including other mammals—cougar, black-tailed deer, mountain goat, black bear, river otter, and Douglas squirrel, for example, as well as hundreds of species of fish, amphibians, birds, and reptiles. These various vertebrates are easily recognized by the unique adaptations that allow them to survive and flourish in their particular habitats within the park. Fish can live in the ponds and rivers because of their scales, fins, and gills; amphibians metamorphose from a water-dwelling juvenile form to an air-breathing adult; birds have hollow bones and feathers that enable many of them to fly; and reptiles have a body covered in water-tight scales that equip them for life on dry land. Each of these animals plays an important ecological role in the park, serving either as food for other animals, or as predators themselves.