D. B. Houston and E. G. Schreiner
The spectacularly rugged Olympic Mountains dominate the landscape of Washington's Olympic Peninsula. Geographic isolation has led to a mammalian fauna that is markedly less diverse than that of the nearby Cascade Mountains and to endemism among native plants and animals. Mountain goats (Oreamnos americanus), introduced into the Olympic Mountains during the late 1920's, have colonized virtually the entire range. Olympic National Park was established in 1938 as a 3700-km2 natural area to conserve the native biota. Goats are now considered by the National Park Service as an unwelcome addition to the fauna.
Mountain goats of Olympic National Park are but one example of the pervasive influence of humans on the earth's biotagreatly accelerating the spread of plants and animals around the globe. Introduced exotic or alien species often disrupt established ecosystem processes and pose management problems for national parks. This is the situation in Olympic National Park: goats have modified the vegetationas all large herbivores doand, thereby, have affected endemic plants.
Mountain goats are among the least known of North America's ungulates. National Park Service personnel studied the biology and management of mountain goats in 1981-92. Fieldwork included studies of mountain goat abundance, demography, habitat relations, and the effects of goat herbivory on the park's vegetation. Park management programs, particularly the experimental management program conducted in 1981-85, enabled us to add considerably to our knowledge of the ecology of mountain goats and to test capture and control techniques. Following the experimental program and an analysis of management alternatives (National Park Service 1987), the National Park Service initiated operational management. We report information from the 1981-92 studies, evaluate the effectiveness of the 1988-89 operational program designed and implemented primarily to eliminate mountain goats from the 3,250-km2 core of the park, and consider goat management options for the future. Our findings increase the knowledge about mountain goats and provide information for biologists that manage these fascinating creatures.
Our intended audience includes the scientific community, the resource managers, and the interested public. Experience in scientific and public forums during the past 15 years has convinced us that the ecological concepts that underlie national park management goals need clear explanation and wider recognition. In this introductory material, we review natural area management including National Park Service policy on the management of introduced speciesto provide information essential to develop an understanding of the mountain goat issue.
Mountain Goats in Olympic National Park
The presence of mountain goats is interpreted to be contrary to the stated purpose of Olympic National Park. Congress determined that the purpose of the park was
National Park Service Natural Area Management
The conservation of nature is generally accepted as the primary goal of parks, but biologists and managers have struggled to define ecological objectives for the large natural area parks, such as Yellowstone and Olympic (e.g., Leopold et al. 1963; Houston 1971; Agee and Johnson 1988).1 A succinct review of worldwide park management goals provides a useful perspective on management alternatives (Shepherd and Caughley 1987:191):
Option 3, with strong emphasis on allowing processes to approach full rein, best describes our perception of the management goals for large United States parks.
Serious questions remain about our ability to meet biological goals in the future. Ecosystems leak. Consequently, a truly self-contained natural area will remain an ideal that cannot be fully achieved; compensatory management may lie in the future for most United States parks, but the level of human intervention required is still unclear. Parks are beset with problems that include the difficulties of fully restoring forces (e.g., fire) that drive ecological processes, the possibility that areas may be too small to maintain viable populations of native species over time (Newmark 1987), and the alteration of ecological processes by the introduction of alien species.
Alien Species in Parks
Biogeography teaches that distributions of plant and animal species change continually through time. The natural distributions of North American species have changed considerably since the waning of the Wisconsin glaciation, a mere 18,000-15,000 B.P. (Pielou 1991).2 Mammal distribution, for example, has changed markedly during just the past 10,000 years, with major shifts of terrestrial species continuing into mid-Holocene times (Graham and Mead 1987; Pielou 1991). The degree to which these shifts in distribution must be considered in designating species status in parks is considered below.
Humans have accelerated the spread of species around the earth. The long-term ecological consequences of these activities are not fully understood (e.g., Elton 1958), but the magnitude of the management problems posed to United States national parks by the introduction of exotic or alien organisms is considerable. In a 1980 report to the Congress, 300 National Park Service areas reported 602 perceived threats to natural resources involving alien plants and animals (National Park Service 1980a).
Concern about alien species in parks was expressed in the scientific community as early as the 1920's (Lien 1991) and was reinforced by National Park Service scientists in the 1930's (e.g., Wright et al. 1933). The concern centered on the disruption of established ecosystem processes by introduced species. Policies on the introduction and management of exotic species evolved in concert with the broader biological goals of parks (Cahalane 1948; Leopold et al. 1963; Wright 1992; J. G. Dennis, National Park Service Research on exotic species and the policy behind that research, San Francisco, unpublished report). Leopold et al. (1963:5) were particularly blunt that the biota of national parks should "... be limited to native plants and animals."
Current policy states, "Exotic species are those that occur in a given place as a result of direct or indirect, deliberate or accidental action by humans (not including deliberate reintroductions). . . The exotic species introduced because of such human action would not have evolved with the species native to the place in question and, therefore, would not be a natural component of the ecological system characteristic of that place." Moreover, "Management of populations of exotic plant and animal species, up to and including eradication, will be undertaken wherever such species threaten park resources or public health and when control is prudent and feasible" (National Park Service 1988).
Interpretation of this general policy is usually straightforward: eastern brook trout (Salvelinus fontinalis) in Yellowstone and Olympic parks, feral goats (Capra hircus) and eucalyptus trees (Eucalyptus spp.) in Maui's Haleakala Park, and European wild boars (Sus scrofa) in Great Smoky Mountains Park are exotic beyond reasonable argument (i.e., within a time frame of millennia). However, troublesome areas remain that involve spatial and temporal scales where policy seems to collide with biogeography. We examine six case histories including three involving challenges to National Park Service policy in which the issue was resolved by the courts.
Burros in Grand Canyon National Park
In the 1970's, the National Park Service proposed to eliminate free-ranging burros (Equus asinus) from Grand Canyon National Park because the animals were exotic (feral since the 1870's or earlier), altered native plant communities, and possibly competed with native wildlife (National Park Service 1979, 1980b). The proposal was contested on several grounds, but the one of interest here involved several paleontologists who viewed burros as the ecological equivalents of late Pleistocene equids (E. conversidens) formerly found in the area. The native equid became extinct about 11,500 B.P., possibly at the hand of early humans (Martin 1970, 1979; Cole 1980). Other scientists and the National Park Service (Carothers et al. 1976, 1979) disagreed with these interpretations because (1) North American equids were related to the North African progenitors of the burro only at the subgeneric level (e.g., Harris and Porter 1980), and (2) late Pleistocene environments no longer occurred in Grand Canyonthat is, plant communities differed, and the array of Pleistocene species associated with the extinct equids (including other large herbivores, predators, parasites, and diseases) were now largely absent. A subsequent legal challenge based in part on the question of the exotic status of the burro failed (Copple 1980; legal papers filed in Civil Case 80-41 6-PHX-WPC). The court also upheld the validity of the broader National Park Service policy on exotic species management.
Burros in Bandelier National Monument
In a related case, a National Park Service proposal to remove burros from New Mexico's Bandelier National Monument was disputed initially on grounds that the agency failed to follow National Environmental Policy Act (NEPA) requirements. The U.S. District Court found in favor of the National Park Service and accepted as finding of fact that burros were exotic species, as defined by National Park Service policy (Burciaga 1980). This decision was appealed by the American Horse Protection Association; arguments again invoked the occurrence of Pleistocene equids and the derivative notion that burros should be considered native to New Mexico. The U.S. Court of Appeals (1982) did not accept this argument or the others concerning NEPA procedural issues, and the National Park Service prevailed.
Bolson Tortoise in Big Bend National Park
The Bolson tortoise (Gopherus flavomarginatus) is an endangered species that occurs in north-central Mexico. Introduction of the tortoise to Big Bend National Park was proposed on grounds that the same or a closely related species occupied the region until late Pleistoceneearly Holocene times (G. Aquirre and G. Adest, Repatriation of Bolson tortoises into Big Bend National Park, Instituto de Ecologia, Durango, Mexico, unpublished report). The fossil record suggests that the tortoise has undergone a reduction in body size and a contraction of geographic range since the late Pleistocene. The tortoise has apparently been absent from the Big Bend area for thousands of years and now occupies 6,000 km2 in Mexico, some 240 km from the park. No assessment has been made of the potential effect of the proposed introduction on the extant flora and fauna of Big Bend. Following detailed review, the National Park Service ruled the tortoise to be an exotic species and therefore inappropriate to introduce into Big Bend, its status as an endangered species notwithstanding (M. Ruggiero, Policy review on proposal to introduce the Bolson tortoise to Big Bend National Park, National Park Service, Washington, D.C., unpublished memo).
Bison in WrangellSt. Elias National Park
Bison (Bison bison) were introduced into Alaska's Copper River (in 1950) and Chitna River valleys (1962)areas subsequently incorporated into Wrangell-St. Elias National Park and Preserve in 1980 (Peek et al. 1987). Bison evidently persisted in Alaska, at least north of the Alaska Range (ca. 500 km from Wrangell-St. Elias), until about 500 B.P., just before European contact (i.e., their extinction was "natural"). South-central Alaska, including Wrangell-St. Elias, was heavily glaciated during Pleistocene advances, and no post-Pleistocene bison remains are known from the area. Additionally, the introduced animals were plains bison (B. bison occidentalis), not the wood bison (B. bison athabascae) subspecies currently recognized by some mammalogists (Meagher 1986). [Note: This may now be an irrelevant issue because Geist (1991) considered B. bison athabascae to be simply an ecotype, not a valid taxon]. Peek et al. (1987) questioned whether or not bison should be considered exotic and suggested that the National Park Service needed to define the concept of native species on temporal and spatial scales. The current Wrangell-St. Elias position is to consider the bison exotic (K. Jenkins, Wrangell-St. Elias National Park, Glennallen, Alaska, personal communication, 1991).
Horses in Ozark National Scenic Riverways
In 1990, the National Park Service proposed to remove feral horses (Equus caballus) by live capture from the "natural zones" of the 327-km2 Ozark National Scenic Riverways. In 1964, the Congress authorized the riverways with an extremely broad enabling statute: "For the purpose of conserving and interpreting unique scenic and other natural values and objects of historic interest.. management of wildlife, and provisions of use and enjoyment of the outdoor recreation resources..." (Higgins 1991). Fewer than 30 horses occupy the riverways, and horses have been present since the 1940's. The proposed removal was challenged by local residents on several grounds, including the contention that horses should be considered native species, wildlife, and cultural resources under National Park Service policy
In June 1992, a U.S. District Court found in favor of the plaintiffs, even though accepting National Park Service arguments that the horses were rightfully classified as exotic species. The court concluded "... that the decision to remove the horses constituted a clear error in judgment as to whether governing statutes and management policies required removal of the horses and the decision failed to consider relevant facts, in particular, the damage caused by removal of the horses and whether the horses are cultural or historical objects" (Limbaugh 1992).
The case was appealed, and in June 1993 the district court decision was reversed. The Court of Appeals found that the earlier decision did not use the proper standard of judicial review of agency decision-making and that there was sufficient evidence that the continued presence of the exotic horses was in conflict with the purpose of the park (U.S. Court of Appeals 1993). Plaintiffs petition for certiorari to the U.S. Supreme Court to examine the appellate court decision was denied, thus the appellate decision stands (W. D. Back, Solicitor, U.S. Department of the Interior, Portland, Oregon, personal communication, 1994).
Mountain Goats at Olympic National Park
Even though early naturalists reported that mountain goats were absent from the Olympic Mountains and that the animals were known to have been introduced in the 1920's, Lyman (1988) challenged the idea that the National Park Service should view the goats as alien species. Lyman's arguments were based on a speculative dispersal model for Oreamnos during the late Quaternary. Based on the model, mountain goats might have occupied the Olympic Mountains during the Quaternary. He also speculated that mountain goats may have been present historically in unexplored areas of the mountains (Lyman 1988).
This challenge prompted the National Park Service to review the basic premise of goats as alien species. The ethnographic record indicated that mountain goats did not occur in the Olympic Mountains during the nineteenth century but that an extensive trade network among native peoples brought goat wool (prized for blankets and garments) and horns (for utensils) to the Olympic Peninsula (Schalk 1993). Goat bones have not been identified in remains from 24 archaeofaunal sites on the peninsula (mostly from the last 1,000 years of the prehistoric record). Schalk (1993) cautioned, however, that because of the temporal range and location of the archaeological sites (mostly coastal areas some distance from the mountains) and the general shifts in mammalian distribution during the late Quaternary. the archaeofaunal data did not permit conclusive statements regarding the presence or absence of goats during the late Pleistocene or Holocene before the nineteenth century.
Schultz (1993 and Appendix B) reviewed historic accounts beginning with the Spanish exploration of the Strait of Juan de Fuca in 1790 and explorations of the mountain range in the late nineteenth century to records from 1925, which was around the time of the goat introductions. Considerably more historical information existed on early conditions in the Olympic Mountains than was reported by Lyman (1988). Schultz noted the difficulties of interpreting negative evidence and the occasional confusion over common names applied casually to wildlife species through the nineteenth century. She concluded that mountain goats were not present historically.
Note that the arguments for possibly considering mountain goats to be native species prehistorically in the Olympic Mountains contain elements of analogous arguments concerning bison at Wrangell-St. Elias and burros at Grand Canyon. The National Park Service continues to view the mountain goats as alien to the Olympic Mountains (National Park Service 1994).
The six case histories raise several philosophical and biological questions for scientists and park managers:
Definitive answers cannot be provided to these questions, but we offer a perspective based on the broader objectives for United States national parks. Granting the dramatic post-Pleistocene changes in species distribution, our understanding is that the national parks were not established to attempt to recreate late Pleistocene or early Holocene biotas. Parks were set aside to conserve the extant biota, in essence to conserve the outcome of the dramatic ecological events of the late Quaternary, including local extinctions, that shaped the exiting flora and fauna. Pragmatically, then, the National Park Service is primarily concerned with historic, post-Columbian species distributions, recognizing that these too change naturally over time. This seems at least to be the implicit interpretation of current policy (National Park Service 1991). This view also recognizes that it is entirely appropriate to restore species eliminated directly or indirectly by Euro-Americans.
If this perspective is valid, then a conservative interpretation of the National Park Service policy on exotics seems prudent because of the relative rarity of large natural areas, their value as baselines or controls for other ecosystems exploited by humans (Jenkins and Bedford 1973), and our general ignorance of ecosystem dynamics and processes (i.e., park resources are always managed with an air of uncertainty; Walters 1986). Introducing species adds to uncertainty. Our inability to predict the outcome of interactions of introduced organisms with either the abiotic forces driving ecosystem processes (e.g., fires, climatic change) or the extant biota means that, with too liberal an interpretation of the exotic species policy, we unnecessarily risk considerable alteration of ecological relations.
From this viewpoint, it is irrelevant that an equid occurred in the Grand Canyon or a tortoise occurred at Big Bend during the late Pleistocene or that a form of mountain goat might have occupied the Olympic Mountains at an earlier time. In the park situations described, these species are prudently classed as exotic, a perspective in accord with the few legal decisions rendered.
Mountain goat management at Olympic National Park has been controversial. No matter how the issue is eventually resolved, the decision must be based, in part, on scientific information. We trust that this monograph provides the information necessary.
Last Updated: 12-Dec-2007