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The northern Rocky Mountains sustain the most diverse assemblage of native ungulates in North America. Species found here include moose (Alces alces), pronghorn antelope (Antilocapra americana), bison (Bison bison), elk (Cervus elaphus), mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), mountain goats (Oreamnos americanus), and bighorn sheep (Ovis canadensis). Still, it is an area increasingly altered by human settlement. Following the Lewis and Clark Expedition, the region experienced periods of fur trapping, market hunting, mining, logging and agriculture-driving many species to the brink of extinction. Today, human population growth and tourism have led to accelerated rates of land development and recreational use, affecting critical wildlife habitats and the populations dependent on them.
In general, ungulates roam widely among distinct seasonal ranges so that, for most species, no single conservation area is large enough and diverse enough to fully encompass their habitat needs. Yellowstone National Park, for example, provides over 2 million acres of habitat for some of the largest native ungulate herds in the lower United States. But like many conservation areas, it includes little of the low-elevation habitats that historically provided ungulates with essential winter range. Thus, elk and bison moving beyond Park boundaries in search of winter forage have sparked bitter debate over appropriate ungulate numbers and distributions. For pronghorn and bighorn sheep, meanwhile, there is concern that Park populations might not be viable in the long term due to isolation and small population sizes resulting from habitat loss. Nor can Yellowstone fully protect the species or habitats within its borders. Exotic weeds compromise plant communities used by native ungulates, introduced diseases have led to culling of bison, and mountain goats transplanted into adjacent, non-historical habitats have spread into the Park, raising concerns about unintended impacts. Implicit within such issues is the need for sound scientific information.
The USGS Northern Rocky Mountain Science Center, through its ungulate research program, is committed to providing the scientific information needed to aid ungulate management decisions. During the past five years, this program has focused on bison research in Yellowstone National Park, with emphasis on the relationship between bison ecology and the epidemiology of brucellosis. Other areas of research included mule deer population ecology on the northern Yellowstone winter range and development of GIS-based ungulate habitat models. Following is a proposed agenda for 2002-2006, with four areas of emphasis. First, bison research will be extended to examine population- and community-level impacts of Yellowstone Park's newly implemented bison management plan, and studies of disease transmission between bison and cattle will continue. Second, demographics and habitat requirements of pronghorn on the northern Yellowstone winter range will be studied to support development of a management plan that ensures the long-term viability of this herd. Third, the Center's ungulate research program will be expanded to include support for Glacier National Park, where demographics and habitat use of bighorn sheep will be studied to aid planning and impact assessment related to relict bighorn populations. Finally, habitat modeling will be expanded from the current pilot project to include more species and areas, refined modeling methods, and internet-based decision support for resource managers. Synopses for these projects follow.
Background.-Bison in the Greater Yellowstone Area harbor an exotic bacterium that causes brucellosis in domestic and wild ungulates, and undulant fever in humans. Following a $3.5 billion effort to eradicate brucellosis from livestock in the United States, wild ungulates in the Yellowstone area comprise one of the last remaining disease reservoirs and jeopardize the brucellosis-free status of livestock in three adjacent states. Between 1984 and 1996, almost 2,000 bison leaving Yellowstone Park were killed to protect that status. A recently completed Environmental Impact Statement, "Bison Management for the State of Montana and Yellowstone National Park," calls for culling potentially large numbers of animals, especially during severe winters. This shift away from Yellowstone Park's natural regulation policy, in place since 1968, has major implications for resource management in national parks throughout the country. Accordingly, the population- and community-level consequences of this new policy merit careful study.
In Grand Teton National Park, free-ranging, brucellosis-infected bison are sympatric with cattle. Research has shown that bison are displaced by and generally avoid cattle, bison cows isolate themselves from other bison and cattle during parturition, brucellosis in bison does not affect reproductive synchrony, and pathogen exposure occurs. However, extent of disease transmission and the degree to which these behaviors minimize or eliminate transmission are unknown. Research is needed on ecological factors affecting disease transmission, and on the clinical significance of viral pathogens in bison.
Proposed Research.-In Yellowstone National Park, population-level effects of the new bison management policy will be studied. Information on the age, sex, and reproductive status of culled bison will be evaluated, together with estimates of population size and composition, and natural mortality patterns. Using these data, impacts of management actions on bison population structure and trend will be assessed. Data will be integrated with epidemiological models to estimate impacts of management actions on the epidemiology of brucellosis.
Community-level effects of Yellowstone's bison management also will be studied. Bison habitat use and selection will be evaluated using GPS-collared animals and ground observations. Timing and duration of habitat use will be measured, then modeled using resource selection functions. In collaboration with scientists from the USGS Geology and Hydrology Divisions, use of thermal areas will receive particular attention. Characteristics of thermal features used by bison will be compared with unused thermal areas. Concentrations of trace elements in bison, and the grizzly bears that prey upon them, will be examined using fetal and maternal tissues and hair samples from bison, as well as grizzly bear hair samples. Significant differences will be followed by an assessment of population parameters of both species in each stratum.
In Grand Teton National Park, research will be undertaken to narrow the temporal scale of potential contact between cattle and bison, and document behavioral patterns during bison/cattle interactions. Seasonal movements of GPS-collared bison will be mapped, emphasizing periods when cattle are present. Movements will be compared with cattle movements and distributions to evaluate risk of disease transmission and the need to modify bison or cattle management. Analyses will quantify types of interactions and qualitatively assess whether interactions are likely to result in disease transmission.
Also in Grand Teton Park, bison will be sampled for presence of infectious organisms, and presence and prevalence will be related to clinical findings. Samples will consist of tissues and fluids appropriate for bovine viral diarrhea, respiratory syncytial virus and pasteurella isolation. Clinical signs, clinical chemistry and hematology will be used to assess effects of pathogens. In addition, pasteurellosis is a known mortality factor in elk, and an environmental reservoir for this disease is likely. Bison will be evaluated as a potential carrier.
Background.-Pronghorn antelope in Yellowstone National Park persist in a small, relict population that is subject to recurrent, severe declines. This genetically unique population is largely isolated from other pronghorn, depends partly on private lands for winter range, experiences heavy predation of fawns, and concentrates during winter in a small area, thereby increasing its vulnerability to disease or locally extreme weather. A recent study estimated that the probability of extinction for this population during the next 100 years is 18%-a figure that is considered unacceptably high. Evidence of a dramatic decline in pronghorn numbers since 1993 and of continued poor recruitment has further heightened concerns. Knowledge of population dynamics, seasonal movements, habitat use and selection, and habitat availability and quality is essential to devising a strategy to ensure the long-term viability of this population.
Proposed Research.-The proposed research will examine (1) population age structure, productivity, and survival, (2) migratory pathways, and partitioning of the population into migratory and non-migratory segments, (3) habitat use and selection, and (4) habitat availability and quality, with emphasis on winter range and spring fawning habitats.
Background.-Bighorn sheep in Glacier National Park occupy patchily distributed habitats, particularly during the critical winter period. Decades of fire suppression have decreased the size and increased the insularity of individual patches, while disease has caused recurrent catastrophic mortality, exacerbated by legal and illegal hunting. Although the relative contributions of these factors are unknown, they have combined to eliminate bighorn sheep from some historical winter ranges in and adjacent to the Park. Because bighorn habitat use patterns are traditional, with knowledge of specific areas being passed from one generation to the next, natural recolonization of these areas is unlikely and an overall reduction in carrying capacity must be assumed. Despite concerns about the status and long-term health of Glacier's bighorns, relatively little is known about their basic ecology. Knowledge of demographics, movements, habitat use, and habitat quality and availability is needed to estimate impacts of the major factors affecting this population, and to devise appropriate management responses.
Proposed Research.-Bighorn sheep habitat use and demographics will studied in the Two Medicine and Many Glacier areas of Glacier National Park. Seasonal ranges and migration routes will be documented using GPS-collared animals. Movements will be analyzed to evaluate habitat use and selection, and habitat use patterns will be modeled using resource selection functions. Habitat models will be extrapolated across the Park to predict occurrences of critical habitats and provide Park managers with rigorous, quantitative tools for planning and impact assessment. Habitat models will be evaluated together with fire history information and fire models to estimate likely impacts of fire suppression on bighorn carrying capacity. Census information, including age and sex composition, will be gathered and used to evaluate population size and dynamics within and among individual subpopulations.
Background.-To devise credible strategies for managing human-wildlife conflicts, managers need information about the importance of specific areas to particular species. In the Greater Yellowstone Area, for example, development of low-elevation areas seriously threatens vital ungulate winter ranges, with obvious implications for both ungulates and their predators. Although ungulate habitat-use patterns have been intensively studied in selected parts of this ecosystem, tools are needed to extrapolate this information in a way that facilitates landscape-level planning and impact assessment. Habitat use models offer one such tool. In an unfunded demonstration project, researchers at the USGS Northern Rocky Mountain Science Center developed spatially explicit, probabilistic models of habitat use patterns for wintering mule deer, elk, and bighorn sheep in the Gardiner Basin area of the northern Yellowstone winter range. Funding is now needed to develop models for other species, extend models to other parts of the ecosystem, and provide these models as interactive, internet-based tools for resource managers, land use planners, and the public.
Proposed Research.-Building on research done to date, the proposed work will focus on four objectives: (1) compile telemetry data for ungulates in the Greater Yellowstone Area, (2) acquire and develop the GIS data layers needed to model ungulate habitat use patterns, (3) develop quantitative, spatially explicit models of ungulate habitat use throughout the Greater Yellowstone Area, and (4) integrate those models into an internet-based decision support system to provide interactive tools for planning and impact assessment.
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U.S. Department of the Interior, U.S. Geological Survey
Northern Rocky Mountain Science Center, BOX 173492, Montana State University,
Bozeman, Montana, 59717-3492
Maintainer: mrblair@usgs.gov
Last Modified: 25 April 2003 11:22
URL:
http://nrmsc.usgs.gov/research/ungulate_research.htm