Author(s): Trevor A. Kinley, Clayton D. Apps
Date: 01-Jan-01
Source:
Number on Library Shelf: 20

Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) occurring in the high-snowfall region of southeast British Columbia. They occur in a series of small subpopulations, some of which are declining. We conducted population surveys and mortality monitoring for mountain caribou in the southern Purcell Mountains of British Columbia from 1994 to 2000. The subpopulation declined, with annual growth rates of 0.62 to 0.88. This was because of low calf recruitment (mean late winter ratio=0.05) and high adult mortality (mean annual rate=0.24). Reasons for low recruitment were unknown, but most known-cause adult mortality was from predation, particularly by cougars (Puma concolor), Mortality was higher for females than males (P=0.03). The southern portion of the study area had a greater proportion of forests less than or equal to 40 years, a higher road density, and was more fragmented than the northern portion. Caribou mortality also was higher in the south than the north (P=0.03). This may have been due in part to post-disturbance changes in the distribution of ungulates favoring edges and early seral forests and the predators that were attracted to these ungulates. If current trends continue, the southern Purcell caribou herd will almost certainly be extirpated within a decade. We recommend augmenting this subpopulation, conducting research into relationships between predation and patterns of forest harvesting and reasons for low calf recruitment, and limiting predation by reducing numbers of cougars and alternate prey.
 

Author(s): Dale R. Seip
Date: 01-Jan-91
Source: Proceedings of the Fifth North American Caribou Workshop.
Yellowknife, Northwest Territories, Canada, 19-21 March 1991.
Heard, D. and Williams, M. (eds) .1991. 170pp.
Special Issue 7:46
Number on Library Shelf: 29

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.
 

A Review of Wolf-Caribou Relationships and Conservation Implications in Canada

Author(s): D.C. Thomas
Date: 27-Aug-92
Source: In: Carbyn, L. N.; Fritts, S. H., and Seip, D. R., eds. Ecology and conservation of wolves in a changing world ; 1992 Aug 25-1992 Aug 27; Edmonton, Alberta. Edmonton, Alberta: Canadian Circumpolar Institute; 1995: 261-607.
Number on Library Shelf: 93

This document discusses some strategies that can be used to conserve wolf and caribou populations in changing environments.
 

Author(s): Dale R. Seip
Date: 12-Feb-92
Source: Canadian Journal of Zoology 70:1494-1503
Number on Library Shelf: 99

http://www.cmiae.org/compendium/reference99.pdf
2.6 MB (scanned)

Caribou (Rangifer tarandus caribou), wolves (Canis lupus), and moose (Alces alces) were radio-collared and monitored in two areas of southeastern British Columbia to determine predator- prey interactions. Throughout the year, wolves and moose used similar areas and habitats, and moose were the primary prey of wolves. In winter most caribou used high-elevation habitats and were spatially separated from wolves and moose living in valley bottoms. In summer, caribou, wolves, and moose at Quesnel Lake used similar areas and habitats, whereas in Wells Gray Park most caribou migrated to rugged, mountainous areas, which kept them spatially separated from wolves and moose. The Quesnel Lake caribou population had a high adult mortality rate (29%/year), wolf predation being the major cause. Calf survival to October was low (2.5/100 adult females) when wolves were present and uncontrolled in the area, but was significantly greater (39/100 adult females) when wolves were reduced or absent. The Quesnel Lake caribou population was found to be declining by about 25%/year, and wolf predation appeared to be the major limiting factor. Caribou in Wells Gray Park had a low adult mortality rate (8%/year) and comparatively high calf survival to October (37/100 adult females). The Wells Gray caribou population was found to be slowly increasing, apparently because its migratory behavior kept it separated from wolves and moose throughout the year, resulting in low wolf predation on the caribou.
 

Author(s): A. T. Bergerud, H. E. Butler, D. R. Miller,
Date: 01-Jan-84
Source: Canadian Journal of Zoology. 62:1566-1575
Number on Library Shelf: 100

A study of mountain caribou (Rangifer tarandus caribou) was conducted from 1987 through 1989 to obtain information on calf survival, calving and summer habitat, timing of spring migration and distances moved to calving areas. In addition, the effect of winter severity and snowfall on calf survival based on data collected since 1981 was assessed. Observations of a sample of radio-collared adult female caribou provided detailed data on calf production, timing of movement to calving sites, calving habitat, fidelity to calving sites and timing of mortality of calves. In years when winters were severe or snowfall was high through April and May, radio-collared females did not move as far from their winter range to calve and calved at lower elevations, than years when winters were of average or above average severity and springs were relatively snow free. Correspondingly, low percentage calves in fall/early winter composition counts were associated with a previous severe winter or late spring. Calving habitat was variable, though located primarily above 1600 m, and calving sites were widely dispersed. Dispersal to higher elevation calving sites was considered to be an antipredator strategy that was disrupted when snow cover on the winter range extended late into the spring. Over nine years of monitoring, the mean percentage calves in fall/early winter composition counts was 14 and four years of low calf survival negated five years of average or above average calf survival.
 

Author(s): Bradley Armstrong Allison
Date: 01-May-98
Source: Thesis, 40 pp. Label:M-862 The University of British Columbia
Number on Library Shelf: 111

The wolf (Canis lupus)/mountain caribou (Rangifer tarandus caribou) spatial seperation model (Seip 1992a) was examined in highland and mountainous area of east central and southeastern British Columbia to determine the influence of wolves on mountain caribou ecology. Three key elements investigated were: the importance of wolf predation as a mountain caribou mortality factor, the elevational relationship of mountain caribou, wolves, and moose (Alces alces) and the seasonal dietary importance of moose to wolves. Mountain caribou mortality data from the Columbia Mountains and Quesnel Lake supported the hypothesis that wolf predation is greater in highland than in mountainous areas. Wolf predation was the main mortality factor of caribou in the highlands around Quesnel Lake, but was a minor factor in the other three study areas. Wolf predation at Quesnel Lake occurred primarily during summer/fall at low elevations. Mountain caribou, wolf and moose radio-telemetry data suggested that wolves in both highland and mountainous areas are more closely associated with moose than caribou throughout the year. Caribou in highland areas appeared as adept as those in rugged mountains at spacing elevationally away from wolves during all seasons. Significant elevational overlap between wolves and caribou occurred only in the rugged Columbia Mountains, and then, only during summer/fall. Wolf scats from the Columbia Mountains indicated that mountain caribou were of lesser dietary importance than moose to wolves throughout the year. Moose, particularly in winter, were the main diet item of wolves. Beaver was an important dietary item of wolves during summer/fall. Elevational separation appears inadequate in explaining the variation in wolf predation on mountain caribou in the highland and mountainous study areas.
 

Author(s): Clayton D. Apps, Bruce N. McLellan
Date: 31-Mar-02
Source:
Number on Library Shelf: 125

Caribou (Rangifer tarandus cariobu), wolves (Canis lupus), and moose (Alces alces) were radio-collared and monitored in two areas of southeastern British Columbia to determine predator-prey interactions. Throughout the year, wolves and moose used similar areas and habitats, and moose were the primary prey of wolves. In winter most caribou used high-elevation habitats and were spatially separated from wolves and moose living in valley bottoms. In summer, caribou, wolves, and moose at Quesnel Lake used similar areas and habitats, whereas in Wells Gray Park most caribou migrated to rugged, mountainous areas, which kept them spatially separated from wolves and moose. The Quesnel Lake caribou population had a high adult mortality rate (29%/year), wolf predation being the major cause. Calf survival to October was low (2.5/100 adult females) when wolves were present and uncontrolled in the area, but was significantly greater (39/100 adult females) when wolves were reduced or absent. The Quesnel Lake caribou population was found to be declining by about 25%/year, and wolf predation appeared to be the major limiting factor. Caribou in Wells Gray Park had a low adult mortality rate (8%/year) and comparatively high calf survival to October (37/100 adult females). The Wells Gray caribou population was found to be slowly increasing, apparently because its migratory behavior kept it separate from wolves and moose throughout the year, resulting in low predation on the caribou.
 

Author(s): John Krebs, David Lewis
Date: Feb 1999
Source: Proc. Conf. on the Biology and Manage. Species and Habitats at Risk, Kamloops, B.C., 15-19 Feb., 1999. Vol. 2; B.C. Minist. Environ., Lands and Parks, Victoria, BC, and Univ. College of the Cariboo, Kamloops, BC. 520pp.
Number on Library Shelf: 130

http://wlapwww.gov.bc.ca/wld/documents/ca08krebs.pdf

We are currently completing a multi-year project investigating demography and habitat use of a harvested population of wolverine (Gulo gulo) in a 7,000 km2 area within the Kootenay region of British Columbia. The study area contains 10 registered trap lines, 2 national parks, a major transportation corridor, 2 hydroelectric reservoirs , and active logging areas and supports a substantial helicopter skiing industry. Wolverine are considered vulnerable by the British Columbia Wildlife Branch; consequently, vital rate data are important for evaluating management/conservation options. A total of 39 (14 F 25 M) adult and subadult wolverine have been captured over 3,700 trap nights using log-box traps baited with available road-killed wildlife. Population estimates for the core 4,000 km2 study area based on 4 years of live-trapping data are 25.6 (95% CI: 15.6-55.3) and 24.0 (95% CI: 14.7-44.3) for 1996 and 1997 respectively. Six of 11 mortalities detected during the study to date have been human caused. Annual survival rate was estimated to be .77 (95% CI:0.66-0.88) for all age and sex categories combined. Reproductive data are being gathered through radio-telemetry and follow-up ground investigations of breeding females after den abandonment. Three 2-kit litters have been produced in 14 adult female reproductive seasons. Four of these juveniles have been captured and implanted with radio transmitters. Natal den sites have been in the Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic zone, and associated with woody debris and/or large boulder talus in undeveloped drainages. Home ranges of males (mean = 1,005 km2) were significantly larger than those of females (mean = 310 km2). At the study area scale, the distribution of wolverine use is highly clumped in 4 distinct utilization peaks. The 2 largest utilization peaks occur within Glacier and Mount Revelstoke National Parks, disproportionate to their land base within the study area. The focus for the remainder of the project is on the monitoring of existing females and kits, and identification and characterization of natal dens in spring 1999. A population census using motion-sensitive cameras will be conducted March-April 1999. Final report and management recommendations will be completed in 2000-01.
 

Revelstoke Mountain Caribou Recovery: An Independent Review of Predator-Prey-Habitat Interactions

Author(s): Francois Messier, Doug Heard, and Stan Boutin
Date: March 2004
Source: Submitted to Revelstoke Caribou Recovery Committee
Number on Library Shelf: 158

www.cmiae.org/compendium/reference158.pdf

The mandate of this panel was:

• To improve collective understanding of the complex predator-prey-habitat interactions that affect mortality of mountain caribou herds within the Revelstoke and Central Rockies area.
• To provide advice regarding prioritized research activities that should be initiated to conserve mountain caribou herds within a context of adaptive management.
• To propose mitigation actions that could be implemented in order to foster recovery of caribou populations in the Revelstoke area.
   

Wolves, Bears, and their Prey in Alaska: Biological and Social Changes in Alaska

Author(s):
Date: 1997
Source: National Academies Press, Washington DC
Number on Library Shelf: 159

http://books.nap.edu/books/0309064058/html/index.html

This book assesses Alaskan wolf and bear management programs from scientific and economic perspectives. Relevant factors that should be taken into account when evaluating the utility of such programs are identified. The assessment includes a review of current scientific knowledge about the dynamics and management of large mammalian predator-prey relationships and human harvest of wildlife in northern ecosystems, and an evaluation of the extent to which existing research and management data allow prediction of the outcome of wolf management or control programs and grizzly bear management programs. Included is an evaluation of available economic studies and methodologies for estimating the costs and benefits of predator control programs in Alaska.
 

Ecological interactions among caribou, moose, and wolves: Literature review

Authors: Thomas Chowns, Cormack Gates
Date: December 2004
Source: National Council for Air and Stream Improvement, Inc. (NCASI). 2004. Technical Bulletin No. 0893. Research Triangle Park, NC:
Number on Library Shelf: 175

http://www.ncasi.org//Publications/Detail.aspx?id=2697

Woodland caribou populations are declining in many areas of Canada and there is concern that the decline may be associated with timber harvesting. Caribou, moose, and wolves share a long evolutionary history and their relationships may become altered by large-scale landscape disturbance. This technical bulletin presents a review of scientific literature pertaining to the hypothesis that increases in moose and wolf populations after timber harvesting have adverse effects on caribou. Specifically, large-scale habitat changes that have allowed moose populations to increase and thereby sustain higher wolf numbers presumably have resulted in excessive predation on caribou, apparently resulting in caribou population declines.

Differentiation of caribou by ecotype rather than phenotype has advantages for conservation purposes. The “forest-dwelling” ecotype of woodland caribou often move across extensive areas at low densities, and populations have been difficult to define and monitor. Woodland caribou and moose often partition habitats on the landscape, such that caribou tend to graze mostly lichens and occupy nutrient-poor forest types, while moose browse vascular plant species such as willows, which are associated with more productive environments. The relatively high reproductive potential of moose enables their populations to respond rapidly to a superabundance of forage produced after forest fires or logging. Carrying capacities for caribou increase more slowly and are likely to decline suddenly after such disturbances.

Some caribou populations experience the effects of multiple predators such as grizzly bears, black bears, cougars, coyotes, wolverines, lynx, eagles, and humans. The predation rate is determined by the predator’s functional and numerical responses to changes in prey density. Some of the most viable caribou populations are those that employ anti-predator strategies which reduce encounter rates with wolves at calving time. These include migrating away from wolf denning habitat, seeking refuge on islands, bogs, and shorelines, and parturient females dispersing away from caribou concentrations.

Food selection by wolves is influenced by profitability relative to energetic costs of travel, especially in snow, and dangers in attacking large prey. If primary prey become less abundant, it may be more profitable for wolves to switch to another prey species. Critical thresholds in predator and prey densities affect population dynamics. In some areas, woodland caribou populations are too low to sustain wolves without alternate prey such as moose. Caribou appear in decline or may be eliminated in areas where wolves exceed critical densities. On the other hand, caribou populations have been known to change by several orders of magnitude, especially where herds are migratory and alternate prey for wolves are low in numbers or lacking. Several factors such as age, nutritional state, season, disease, parasites, and genetic load are capable of affecting caribou vulnerability to predation. The very young and the very old are usually the most heavily preyed upon.

Recent changes in ungulate and carnivore distributions may be influenced by climate change and human activities. Measures implemented to conserve woodland caribou populations include hunting restrictions, reintroductions, predator control, parks and protected areas, and national and provincial recovery strategies.

Caribou habitat and commercial forest overlap in some regions and the effects of forestry on caribou vary according to the ecological setting. Roads and seismic-exploration trails may allow greater penetration of wolves into areas occupied by caribou, and vehicular traffic may displace caribou into closer proximity to moose and wolves. The design of forest harvest pattern may significantly affect predator-prey relationships. A mosaic of small cutovers across extensive areas or cutting upland sites in close proximity to fen/bog habitat may be undesirable for caribou management. Silvicultural activities that are compatible with lichen retention and discourage moose browse production are expected to be the most beneficial for caribou. Although fire control may conserve caribou habitat in the short term, fire is an integral part of the boreal forest and this animal is adapted to a fire environment. Further research and management needs have been recommended.
 

Relating predation mortality to broad-scale habitat selection

Authors: Philip McLoughlin, Jesse Dunsford and Stan Boutin
Date: 2005
Sources: Journal of Animal Ecology 2005, 74, 701-707
Number on Library Shelf: 170

Summary:
1. Few studies have related metrics of fitness to broad-scale, multivariate patterns of resource selection.

2. Our objective was to relate long-term predation-mortality patterns for adult woodland caribou [Rangifer tarandus caribou (Banfield)] from Alberta, Canada (1991–2002), with patterns of multivariate habitat selection.

3. We first compared probabilities of radio-tracked caribou dying (n = 55) from predation in habitats within the home range, controlling for habitat availability, with that expected from habitat selection probabilities for the same animals during life. We then compared survival rates of caribou ( n = 141) possessing dissimilar patterns of habitat selection using a Cox proportional hazards regression model.

4. Patterns in habitat-specific predation mortality differed significantly from expected given probabilities of habitat selection during life (P < 0•0001). Cox regression indicated that mortality rates of caribou due to predation were affected significantly by and can be predicted from patterns of selection ( P = 0•02).

5. Our results strongly suggest that uplands (primarily mixed deciduous and coniferous forest) present caribou with higher than expected levels of predation risk, and that caribou can avoid predation by maximizing selection of peat lands (open, conifer dominated bogs and fens).

6. Approaches presented in this study may be useful for ecologists interested in assessing the influence of mortality factors on broad-scale, multivariate resource selection. Linking metrics of fitness to multivariate resource selection will enable us to ask questions of evolutionary ecology once restricted to only the finest ecological scales.
 

Ecological interactions of mountain caribou, wolves, and moose in the north Columbia Mountains, British Columbia

Author: Shannon A. Stotyn
Date: Spring 2008
Source: Master’s thesis, University of Alberta, Edmonton
Number on library shelf: 180

www.cmiae.org/compendium/reference180.pdf

The Southern Mountain population of mountain caribou (Rangifer tarandus caribou) is threatened in Canada, with predation the proximate cause of these declines. To reduce predation risk, caribou isolate themselves from predators and other prey species. I examined the spatial partitioning of mountain caribou, moose (Alces alces), and wolves (Canis lupus), and mortality sources of caribou in the north Columbia Mountains, British Columbia (2003 – 2006). Spatial separation between caribou and wolves was highest in late winter and lowest in spring and calving season. Engelmann spruce/subalpine fir forests, alpine areas, and old forests (> 140 yrs) were important variables that separated these species. The main predator of adult caribou was bears, with wolf predation increasing in importance after 2000. Wolf diet was comprised of moose (91 – 99%) with small relative proportions of caribou, deer, and beaver. This information will provide critical information for effective wildlife management and planning caribou recovery strategies.