Predation and caribou populations

Predation, especially wolf (Canis lupus) predation, limits many North American caribou (Rangifer tarandus) populations below the density that food resources could sustain. The impact of predation depends on the parameters for the functional and numerical response of the wolves, relative to the potential annual increment of the caribou population. Differences in predator-avoidance strategies largely explain the major differences in caribou densities that occur naturally in North America. Caribou migrations that spatially separate caribou from wolves allow relatively high densities of caribou to survive. Non-migratory caribou that live in areas where wolf populations are sustained by alternate prey can be eliminated by wolf predation

Ecosystem management and the conservation of caribou habitat in British Columbia

Woodland caribou (Rangifer tarandus caribou) in British Columbia inhabit a wide variety of forest ecosystems. Numerous research projects have provided information that has been used to develop caribou habitat management recommendations for different areas. Recently, the province has implemented guidelines to protect biodiversity that are based on an ecosystem management strategy of mimicking natural forest conditions. There is a great deal of similarity between caribou management recommendations and biodiversity recommendations within different forest types. In mountain caribou habitat, both approaches recommend maintaining a landscape dominated by old and mature forests, uneven-aged management, small cutblocks, and maintaining mature forest connectivity. In northern caribou habitat, both approaches recommend maintaining some older stands on the landscape (but less than for mountain caribou), even-aged management, and a mosaic of large harvest units and leave areas. The ecosystem management recommendations provide a useful foundation for caribou habitat conservation. More detailed information on caribou and other management objectives can then be used to fine-tune those recommendations

Introduction to the Population Ecology of North American Caribou

Bergerud has discussed how major differences in caribou density across North America appear to be related to the impact of wolf (Canis lupus) predation, and the strategies used by caribou to avoid wolves. Caribou living in areas without wolves usually occur at high densities and are regulated by competition for food. In this session, we asked the presenters to discuss the population ecology of different caribou herds in North America and to evaluate if they fit the general model

MOUNTAIN CARIBOU INTERACTIONS WITH WOLVES AND MOOSE IN CENTRAL BRITISH COLUMBIA

Mountain caribou (Rangifer tarandus caribou) populations in south-eastern British Columbia are declining over most of their range and are listed as Threatened. Predation has been documented as the major cause of declining caribou numbers. Excessive predation by wolves (Canis lupus) has been related to increased moose (Alces alces) numbers. The increase in moose appears to be the result of a natural colonization process that has been enhanced by human-caused habitat change. Options to reduce the rate of predation include reducing wolves, reducing moose, and reducing the amount of early seral habitat that supports moose. Current management includes population control of moose and wolves. Monitoring and assessment of these approaches will guide the future management strategy used to maintain mountain caribou in south-eastern British Columbia

Comparison of seasonal habitat selection between threatened woodland caribou ecotypes in central British Columbia

Woodland caribou (Rangifer tarandus caribou) in British Columbia have been classified into ecotypes based on differences in use of habitat in winter. Although recovery planning focuses on ecotypes, habitat use and selection varies within ecotypes. Our objectives were to compare habitat use and selection among previously identified woodland caribou herds at the transition zone between northern (Moberly, Quintette, and Kennedy herds) and mountain (Parsnip herd) ecotypes in central British Columbia. We developed selection models for each herd in spring, calving, summer/fall, early and late winter. Topographic models best predicted selection by most herds in most seasons, but importance of vegetation-cover was highlighted by disproportionate use of specific vegetation-cover types by all caribou herds (e.g., in early winter, 75% of Kennedy locations were in pine-leading stands, 84% of Parsnip locations were in fir and fir-leading stands, and 87 and 96% of locations were in alpine for the Moberly and Quintette herds, respectively). Using a combination of GPS and VHF radio-collar locations, we documented some spatial overlap among herds within the year, but use of vegetation-cover types and selection of elevations, aspects, and vegetation-cover types differed among herds and within ecotypes in all seasons. Habitat use and selection were most similar between the two northern-ecotype herds residing on the eastern side of the Rocky Mountains. This research indicates that habitat use and selection by caribou herds in all seasons is more variable than ecotype classifications suggest and demonstrates the value of undertaking herd-specific mapping of critical habitat for woodland caribou

Foraging ecology and nutrition of Stone’s sheep

This study compared the foraging behaviour and nutrition of Stone's sheep (Ovis dalli stonei) which had access to burned range to that of sheep on unburned range throughout the year. In winter, sheep were restricted to areas with less than 25-30 cm of snow. For most sheep this meant windswept, alpine ridges, but one small population used a burned, subalpine slope. Grazing pressure was high on these restricted winter ranges, particularly during a severe winter, resulting in removal j of all the forage from alpine range, and leaving only very poor quality forage on the subalpine range. The poor winter nutrition was reflected in low fecal nitrogen and DAPA levels and high Protostronqylus counts. In spring, sheep used either natural or fire-induced subalpine clearings to obtain early new plant growth. Forage quantity was much lower on unburned ranges, but biting rate and foraging time were the same as on burned ranges with high forage biomass. Quality of available forage and food intake were also similar. The foraging behaviour of Stone's sheep appeared to be similar to domestic sheep in that intake rate was primarily dependent on grass length rather than forage density. Sheep moved to higher elevations as the season progressed which provided them with access to the higher quality alpine forage. Regular use of mineral licks in summer apparently satisfied their sodium requirement. Grasses and sedges were the most important foods throughout the year although forbs and browse were important in the summer. Adult mortality rates were low. Lamb production was low following severe winters, presumably due to poor nutrition. An explanation for changes in lamb production based on density-dependent selective feeding was developed. Burned ranges were of limited value to Stone's sheep because they were usually unavailable as winter range, did not provide superior spring range and were not used in summer. Horn growth, however, appeared to be slightly better on burned ranges. A model of nutrient intake is developed to investigate the seasonal pattern of nutrition on burned and unburned ranges.Forestry, Faculty ofGraduat

Appendix B. Maps depicting the relative probability of occurrence of male grizzly bears in the plateau landscape of the Parsnip River study area, British Columbia, Canada, 1998–2003, based on study-wide extent, home range extent, and buffer extent.

Maps depicting the relative probability of occurrence of male grizzly bears in the plateau landscape of the Parsnip River study area, British Columbia, Canada, 1998–2003, based on study-wide extent, home range extent, and buffer extent

Appendix C. Maps depicting the relative probability of occurrence of female grizzly bears in the mountain landscape of the Parsnip River study area, British Columbia, Canada, 1998–2003, based on study-wide extent, home range extent, and buffer extent.

Maps depicting the relative probability of occurrence of female grizzly bears in the mountain landscape of the Parsnip River study area, British Columbia, Canada, 1998–2003, based on study-wide extent, home range extent, and buffer extent