Mountain Goats in Olympic National Park: Biology and Management of an Introduced Species

摘要: Mountain goats (Oreamnos americanus), introduced to the Olympic Mountains during 1920's, are regarded now by National Park Service as unwelcome additions unique biota of (3,700 km2). We report results studies mountain goat biology and management activities conducted in 1981-92. Thirty-five endemic forms plants animals currently recognized on Peninsula. The native mammalian fauna coniferous flora impoverished compared nearby Cascade (12 fewer mammals, 5 conifers). Goats colonized about 60 years. population consisted quasi-independent subpopulations that grew declined asynchronously. meta -population was estimated helicopter census be 1,1 75 ± 171 (SE) 1983 389 106 1990; removals contributed decline. were removed from Klahhane Ridge subpopulation examine changes demography physical condition. Initial breeding age declined, litter size increased, production recruitment kids less variable at lowered densities. Changes associated with increases live weights fat reserves. Marked differences reproductive performance occurred among females. seasonally migratory occupied subalpine alpine areas above 1,520 m summer. closely rocks cliffs all seasons ate a wide variety foods, including four plant taxa. Group averaged than three summer winter. Eighty-four percent 125 tagged showed fidelity ranges, some for 5-10 Interspecific competition resources between could not demonstrated scant data available. Our work changed vegetation Mountains, finding held common other ungulate grazing systems. Six hundred ninety-nine plots herbivory distributed throughout park m. Permanent ranges composition meadows; disturbance-oriented species (e.g., Achillea millefolium) increased selected forage Festuca idahoensis). cover negatively correlated density sites initially high levels herbivory. Sixty-six photographic comparisons also amount exposed mineral soil related range habitat 33 rare taxa 7 peninsula endemics-overlapped considerably. affected killed individual grazing, wallowing, trampling, but our preliminary determine trends populations subjected Circumstantial evidence suggested may have reduced densities Astragalus australis var. olympicus Mount Angeles Blue Mountain. Effects sporadic--sometimes intense--and had unknown long-term consequences survival species. Goat 1980's an experimental program (1981-87) operational (1988-89). About 693 captured 1977 1989, personnel gained considerable experience different capture removal techniques. During 1981-89, 407 park. terminated when continued posed unacceptable risks team. Field sterilizations attempted 19 goats(l3 females, 6 males) evaluate this control technique. cost effort required implement strategic options future (ranging elimination allowing entire achieve ecological carrying capacity) explored using models. All or will difficult expensive practice. Tactical available intense limited shooting aerial capture; sterilization techniques could, best, partially population.