Review of Scientific Material Relevant to the Occurence, Ecosystem Role, and Tested Management Options for Mountain Goats in Olympic National Park

Executive Summary

May 2000

Exotic species, also known as non-native or introduced species, are a legitimate concern to managers of national parks and to conservationists generally. Conservation biologists consider exotic species second only to direct habitat destruction in magnitude of threat to rare species and biodiversity. In many cases these species out-compete native species or threaten them by such activities as grazing or trampling. Examples of this kind of damage can be found in many national parks. The current policy of the National Park Service states, "exotic species are those that occur in a given place as a result of direct or indirect, deliberate or accidental action by humans." The policy further states that "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." Thus, in order to justify control or eradication, three conditions must be fulfilled: 1) the species must be demonstrated to be an exotic; 2) it must be documented to threaten park resources or public health; and 3) control of the species must be prudent and feasible.

The mountain goat (Oreamnos americanus) was introduced to Olympic National Park, Washington, in the 1920s. Scientists with the National Park Service, as well as many others, are concerned that the goats are causing damage to the vegetation of the alpine and subalpine landscape, and may threaten the existence of rare plants, some of which are found nowhere else but in the Olympic Mountains. The National Park Service has determined that all three conditions--non-native status, threat to park resources, and feasible and prudent control--are met in this case, and is considering what control measures to implement for the goat. Some outside critics, however, have cast doubt on all three conditions and argued that more research is needed before decisions are made regarding management of the mountain goats. Our team of scientists was called in to review the scientific evidence that bears on these questions.

We reviewed the scientific material, including published and unpublished literature that relates to the three conditions of the National Park Service's exotic species policy, with respect to the mountain goat in Olympic National Park. Our search was comprehensive, including articles published in refereed scientific journals, agency technical reports, agency internal documents, unpublished academic works (e.g., theses), conference proceedings, industry-sponsored research reports, commentaries and letters from interested individuals and organizations, and, where possible, the primary field data from which the literature was derived. We reviewed national park documents (including photographs) and took a helicopter tour of goat-inhabited portions of the park.

With respect to the first condition, we find that the preponderance of evidence supports the view that the mountain goat has never been native to the Olympic Peninsula. Although negative evidence is not proof of absence, there is no evidence to refute the hypothesis that mountain goats never occurred in the Olympic Peninsula prior to their introduction in the 1920s. The environmental history of the Peninsula over the last tens of thousands of years makes the probability relatively low that mountain goats could have colonized the Peninsula naturally. With respect to the second condition, we find that scientific evidence available at this time is insufficient to establish that the activities of mountain goats are causing significant damage to vegetation, leading to declines in populations of rare plants, or are otherwise having negative impacts on the natural ecosystem. This does not mean that significant impacts have not occurred, only that previous studies were incapable by their design of separating the effects of goats from other variables, such as the effects of weather. Finally, with respect to the third condition, our team finds that control of mountain goats in Olympic National Park would be prudent and feasible.

In conclusion, our study does not provide unambiguous support for implementing the National Park Service's exotics policy in this instance. The relative importance of the three criteria--non-native status, threat to park resources, and feasible and prudent control--must be determined at a policy level. This is a decision that goes beyond science.

For more information, please contact Jim Strittholt.