Wildlife Refuge

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Wildlife refuge

When President Theodore Roosevelt issued an executive order making Pelican Island, Florida, a federal bird reservation, he introduced the idea of a national wildlife refuge . Nearly 90 years later, Roosevelt's action has expanded to a system of more than 400 national wildlife refuges with a combined area of over 90 million acres (36 million ha).

Roosevelt's action was aimed at protecting birds that used the islands. Market hunters had relentlessly killed egrets, herons, and other aquatic birds for their feathers or plumes to adorn women's fashions. The first national wildlife refuge, like other conservation practices of the early twentieth century, emerged in reaction to unregulated market hunting . Pelican Island became a sanctuary where wild animals, protected from gunfire, would multiply and then disperse to repopulate adjacent countryside.

States followed suit, establishing protected areas known variously as game preserves , sanctuaries, or game refuges. They were expected to function as breeding grounds to repopulate surrounding countryside. Although protected populations usually persisted within the boundaries of such refuges, they seldom repopulated areas outside those boundaries. Migratory waterfowl enjoyed some success in repopulating because they could fly over unsuitable habitats and find others that met their needs. Nonmigratory or resident species often found themselves surrounded by inhospitable tracts of farmlands, highways, and pastures. Dispersal chances were limited. Resident populations, particularly those of deer and other large herbivores, built up to unhealthy levels, depleting natural foods, becoming infested with heavy parasite loads, and leaving the animals susceptible to starvation. In short, refuges proved to be too small and too scattered to compensate for changes in the overall landscapes imposed by expanding human populations.

Yet elements of the refuge idea proved to be sound, even critical, under some conditions. The U.S. Fish and Wildlife Service administers the National Wildlife Refuge System and, in keeping with its legal responsibilities, designed the system to provide crucial habitat reserves for migratory waterbirds. Roughly 80% of the refuges in this system were established to provide breeding grounds, wintering grounds, or migration stopover sites for aquatic migrants. The task of providing critical habitat for threatened and endangered species , another area of federal commitment, has been added to this mission.

As wildlife researchers learned more about habitat needs, survival rates, and the dispersal abilities of birds and mammals, wildlife managers began to redefine refuges more in terms of meeting habitat needs than in providing sanctuary from hunters. Without considering habitat quality both on the refuge itself and along its boundaries, no level of protection from gunfire could ensure perpetuation of native wildlife.

Pelican Island is a true island off the Florida coast; other refuges are, or soon will be, habitat islands surrounded by a sea of farms, ranches, forest plantations, shopping malls, and suburbs. There is increasing evidence that even those refuges providing the highest quality habitat may simply be too small to sustain many of their wild species under conditions of isolation.

But how much is enough? How large must a habitat refuge be to ensure that its populations will survive? Nature provides a clue through an experiment that began 10,000–11,000 years ago at the end of the last ice age . As the glacial ice melted, sea levels rose. Coastal peninsulas in the Caribbean and elsewhere became chains of islands as the rising waters covered lower portions of the peninsulas.

The original peninsulas presumably had about the same number of vertebrate species as did the adjacent mainland. By comparing the numbers of birds, mammals, reptiles, and amphibians present on the islands within historical times with those on adjacent mainlands, biologists have found that the islands contain consistently fewer species. Furthermore, the number of species that a given island maintained was correlated directly to island size and inversely to distance from the mainland.

The most likely explanation for this pattern is that the smaller the island, the less likely that species will survive in isolation over long periods of time. The greater the distance, the less likely that wild animals will re-colonize the island by making it across from the mainland.

Should we consider this analogy realistic? After all, most refuges are surrounded by land, not water. Several studies from national parks in the American West, areas protected from both hunting and habitat alterations, have compared the number of large mammal species surviving in the parks. These studies show consistently that the bigger the park, the greater the number of surviving species of large mammals.

Large carnivores such as wolves , bears, lions, tigers , and jaguars need the largest expanses of protected areas. Because they attack livestock (and occasionally humans), large carnivores have long been subjected to persecution. However, there are biological reasons for their rarity as well. Any given level in the food chain/web can exist at only a tiny fraction of the abundance of the level beneath it. It may take 100 or more moose (Alces alces ) to support a single wolf (genus Canis ) or 1,000 Thompson's gazelles (Gazella thomsonii ) to sustain one lion (Panthera leo ). These conditions mean that large carnivores occur at low levels of abundance and range over large areas. Simulation models that take into account the areas needed for long-term perpetuation of lions or bears suggest that even the largest national parks and other protected areas may be too small. Either the protected areas themselves will need to be expanded substantially or the populations will have to be aided by reintroduction of individuals from outside the protected zones.

Although large carnivores remain controversial, they also offer popular appeal to a growing segment of the public. Refuges, parks, and other protected sites large enough to support a population of tigers or wolves, even for a short time, will almost certainly be large enough to meet the needs of other wild species as well. Thus, Project Tiger in India helped sambar (Cervus unicolor ) and chital deer (Axis axis ) populations by defining areas as tiger preserves.

In the United States and Canada, people tend to think of national parks as scenic areas for tourism and recreation . But national parks also act as refuges by protecting wildlife from direct exploitation and by attempting to preserve original habitat conditions. The grizzly bear (Ursus arctos )once ranged from the western prairies to the Pacific Ocean. By the end of World War II, the only grizzly bear populations in the lower 48 states occurred in and around two large national parks: Yellowstone National Park and Glacier. Had it not been for these parks, the grizzly bear would have become completely extinct in the United States, exclusive of Alaska, during the first half of the twentieth century.

Worldwide standards for refuges, parks, and other protected areas have been developed by the United Nations (UN), the IUCN—The World Conservation Union , and the IUCN's World Commission on Protected Areas. These agencies compile listings every five years according to three general criteria. To be included, an area must be at least 2,500 acres (1,000 ha) with the exception of offshore islands of at least 250 acres (100 ha), have effective legal protection and adequate de facto protection, and be managed by the highest appropriate level of government.

The 2000 tally by the IUCN/UN lists over 30,000 protected areas with a total area of 5.1 million sq mi (13.2 million sq km), about 9.5% of the earth's land surface, or roughly the size of China and India combined. Of the 193 major habitat types, 183 are represented by at least one protected area.

The number of internationally recognized areas of protected habitats grew from about 1,800 in 1970 to nearly 7,000 by 1990 and 30,000 by 2000. This expansion resulted from improved cooperation between nations and from the growing realization that without protected areas, the earth's wildlife would be in peril. During the next quarter century, the list of protected areas will likely continue to grow, especially in developing nations. They will become increasingly valued for tourism and for national prestige. The effectiveness of refuges in the more distant future will depend on population growth and on how quickly people shift from extractive to sustainable land use practices. The current tendency to view habitat protection as the antithesis to economic development will fade as people recognize the importance, both ecologically and economically, of maintaining the world's wildlife.

[James H. Shaw ]