Though difficult to measure, nonmarket values must be taken into account in discussing the state of wildlife. These values can be described in terms of the cultural, religious, scientific, and aesthetic importance of wildlife species (Bawa and Gadgil, 1997; Goulder and Kennedy, 1997; National Research Council, 1999). At times, monetary value can be assigned to nonmarket aspects, such as a tourist's willingness to pay to see wildlife in natural habitats (e.g., Edwards, 1991). Although this is difficult, monetary values might be able to be assigned to some of the wildlife services described in this section. The fact that a monetary value is difficult to assign should not diminish the importance of the service; for many, no substitute exists for the services provided by wildlife.
Tools used to assess nonmarket monetary values vary, but a few approaches have become common. One attempts to determine "existence value": people's willingness to pay to know that an animal simply continues to exist, even if they never see it (National Research Council, 1999). Similarly, an "option value" is based on a person's desire to be able to potentially interact with the animal some time in the future, and a "bequest value" is being assured that future generations will be able to use or view an animal (National Research Council, 1999). Listed below are some areas where it is particularly difficult to estimate a monetary value for animal-related services.
Many indigenous peoples use wildlife as integral parts of their cultural and religious ceremonies. For example, birds are strongly integrated into Pueblo Indian (United States) communities. Birds are regarded as messengers to the gods and a connection to the spirit realm. Among Zuni Indians (United States), prayer sticks with feathers from 72 different species of birds are used as offerings to the spirit realm (Tyler, 1991). In Boran (Kenya) ceremonies, selection of tribal leaders involves rituals that require Ostrich (Struthio camelus) feathers. Birds also are used for tribal cosmology, meteorology, religion, and cultural ceremonies (Isack, 1987). Wildlife plays similar roles in cultures elsewhere in the world. Thus, shifts in the timing or the ranges of wildlife species could impact the cultural and religious lives of some indigenous peoples.
Researchers have been studying spider silk to learn how this strong and elastic material could be manufactured (Xu and Lewis, 1990). Similarly, scientists have examined the structure of the small scales on butterfly wings to understand how they reflect light and dissipate heat. These studies may help engineers design better processes for manufacturing and designing computer chips (Miaoulis and Heilman, 1998). Researchers also have studied the regenerative properties of cells within rhinoceros horns and have identified potent antimicrobial chemicals from frogs and toads (Cruciani et al., 1992; Moore et al., 1992; Boskey, 1998).
Other valuable services are provided by species that contribute to ecosystem health and productivity. Reductions in or losses of species can lead to reduced local biodiversity and changes in the structure and function of affected ecosystems (National Research Council, 1999). The most well-known example of this kind of effect comes from marine systems, where the presence or absence of a starfish species has been found to greatly influence the species composition of intertidal habitats (Paine, 1974). Species in terrestrial systems also can have a strong influence on the biodiversity of their ecosystems; in many cases these effects are related to their functions as pollinators or seed dispersers (see Price et al., 2000).
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