Woodland Caribou (Rangifer Tarandus Caribou)
- Assessment Summary
- Executive Summary
- COSEWIC Mandate, Membership and Definitions
- Lists of Figures, Tables and Appendices
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Populations
- Existing Protection or Other Status
- Summary of Status Report
- Technical Summary
- Acknowledgements and Biographical Summary of Authors
- Authorities Consulted, Collections Examined and Literature Cited
Summary of Status Report
At-risk designators should consider four of eight COSEWIC NEAs, which have distinct populations. The Newfoundland population is treated separately from the Boreal population. The genetics of more local populations must be sampled before the systematics can be clarified. Caribou in the Cordilleran Mountains differ from those to the east. Caribou in the southern mountains are mixtures of two founding clades with the northern clade predominating. Sampled populations in central and southern Yukon are entirely of northern origin. Phenological data suggests that caribou in the Northern Mountain NEA are likely to be of northern origin. They once were given subspecies status. All caribou in the Southern Mountain NEA are likely to be mixed populations, that is, derived from northern and southern clades. That is justification for treating the Northern Mountain population separately from the Southern Mountain. Limiting factors and management concerns also differ markedly between the populations (Table 7). Winter feeding obligations would appear to be less important in separating groups of caribou. For example, caribou in south Jasper National Park adopt both terrestrial and arboreal feeding behaviours.
Caribou in Newfoundland probably have been isolated for thousands of years and therefore have no introgression of genes from the northern clade. The same likely is true for the Gaspésie population, which may be depauperate from inbreeding and genetic drift. Both of these COSEWIC populations can be considered genetically distinct. The Pukaskwa local population also was only of southern origin; however, only four caribou were examined.
Based on results for three local populations in the Boreal population (Fig. 2), it is expected to be a mixed population predominantly derived from the southern clade. This justifies separating it from Southern Mountain and Newfoundland populations.
Justification for excluding forest-tundra (taiga-tundra) caribou includes a mixed origin, migratory behaviour, and differences in demographics, predator prey relationships, and current and future habitat loss and alteration from human activities. Caribou in commercial forests are most at risk. What may conserve some of them is their ecological niche – the use of large peatland complexes where timber values are low. Such complexes require forest buffers and movement corridors. Of concern is desiccation of peatlands from climate warming, peat extraction, and draining to enhance tree production.
Assessment of the status of the five COSEWIC populations should be based on habitat trends, numbers and trends in numbers, areas occupied by local populations, concerns for threats and limiting factors, degree of monitoring, state of current knowledge, and significance of protected areas. Those data were collated from all jurisdictions in an attempt to standardize data. The indicators of population status developed for this report will permit an objective tracking of changes in the next status report. Indicators of population status in this report should be ranked in importance and new ones developed that place more emphasis on past and predicted habitat change (Appendix 4). Monitoring and mapping of distributions in GIS systems is important because demographics are difficult to measure and are highly variable. Predicting trends in habitat supply is a critical data requirement. For example, areas of usable (“effective”) habitat will quickly decline as the second pass in two-pass forest harvest system is achieved.
Not enough is known about the ecology of local populations to calculate the probability of survival under specified future conditions. Data requirements for predicting population viability include five “process” variables: demographic, genetic, and environmental stochasticity (variability), density dependence, and catastrophe, as well as five population variables: population size, age structure, sex ratios, life history traits (presumably fecundity and mortality), and habitat quality and availability (Reed et al. 1998). Beissinger and Westphal (1998) list 23 variables of which 4, 10, 19, and 23 must be measured for four increasingly complex models used in population viability analysis. Seldom are data adequate for any of the variables. Therefore, current status of local populations and COSEWIC populations and any prediction of change are accompanied by a high degree of uncertainty. Uncertainty includes demographics of populations, degree of environmental change, and management policy. We can only assume that changes over the past decade or two will continue at the same rate or will accelerate.
Northern Mountain Population (NMP)
The population estimate in 2000/2001 is about 44 000 in 36 local populations (Table 2, Appendix 1a). Most local populations are about stable with increases about balancing decreases. Four local populations are up in number, 15 are about stable, 3 are down, and trends for 14 are unknown (Table 3). In 1996, trends in numbers were 5 increasing populations, 11 stable, 3 decreasing, and 19 unknown (Table 2) (Farnell et al. 1998, Heard and Vagt 1998). Populations of unknown status generally are in remote areas with few developments. Local population numbers are larger than 250 and 500 for 75% and 56% of the populations (Table 4). All but 3 of 32 local populations have ranges larger than 2 000 km2 and 20 and 13 are in ranges larger than 5 000 and 10 000 km,2 respectively (Table 5). Greatest concerns are hunting, predation, and fire (Table 7). Population estimates are obtained occasionally for 79% of known local populations and radio collars were deployed on 59% of them (Table 8). The habitat, with a few exceptions, is relatively intact though there is increasing fragmentation from roads and other linear developments. There is a likelihood that the rate of development will increase over the next decades and management of wolves and unregulated hunting and will be difficult.
Southern Mountain Population (SMP)
Numbers declined in the 1970s and 1980s from population highs in the 1960s subsequent to wolf control (Bergerud 1978, Edmonds and Bloomfield 1984, Edmonds 1988). They also declined in a protected population in south Jasper National Park (Stelfox et al. 1978, Brown et al. 1994). In studies of radio-collared caribou, wolf predation was the primary source of mortality.
In B.C, extent of occurrence has shrunk by up to 40% and most of that concerns the SMP. Many local populations are small, highly fragmented, and subject to rapid loss and alteration of habitat because of multiple industrial developments. Altered habitat has subjected local populations to multiple increased threats including predation, more parasitism, and greater unregulated hunting.
The population estimate is about 7200 (6300 adults) in 30 local populations. Trend in numbers is down for 12 of 30 local populations and stable in 13 (Table 3). Population status has deteriorated since 1996, when three local populations were considered to be increasing, eight were stable, and seven were decreasing (Table 2) (Heard and Vagt 1998, Edmonds 1998). Numbers are a concern as all but two of the 30 local populations contain fewer than 500 caribou, 21 contain fewer than 250, and 8 contain fewer than 50 caribou (Table 4). Range sizes are relatively small with 63% (19/30) of the populations occupying less than 5000 km2 (Table 5). The primary concern is the effects of forestry and other developments including increased access and disturbance, actual and functional loss of habitat, increased isolation of local populations, and increased predation (Table 7). Predator-prey relationships have changed and there is increased access by predators and hunters. The degree of monitoring is high with numbers estimated annually or occasionally for 97% of the local populations (Table 8). Radio collars were used on 87% of the local populations to monitor movements, habitat use, and mortality. Most of the 150+ caribou collared in west-central Alberta (Dzus 2001) were the “mountain” ecotype.
The South Selkirk population, is officially listed as endangered in the United States. Cougar predation, habitat changes from human activities, and wildfires are primary concerns (Zager et al. 1996). The South Purcell’s population is in dire straits and is unlikely to persist because of habitat changes and increased numbers of predators. Translocation of caribou from another population to the South Purcells is proposed by Kinley and Apps (2001). The Alberta government declared caribou to be threatened in 1985 (Edmonds 1988, Alberta Environmental Protection 1996). In 1991, caribou were placed on the Red List (risk of local extirpation) and in 1996 downgraded to the Blue List (may decline to non-viable population levels).
Concern for caribou in the Southern Mountain and Boreal populations stems partly from current trends in numbers (Tables 2 and 3) and shrinking distributions (Fig. 4 and 5). Assuming continuation of a 2.47% annual rate of decline from 1997 to 2002 in B.C., numbers are projected to decline 39% in the next 20 years. Of great concern is future declines in habitat quantity and quality, increased isolation of small local populations (Table 4) in small geographic areas (Table 5), and increased predation. Caribou are unlikely to persist in areas undergoing extensive and intensive development unless predation and hunting are almost eliminated and there are special provisions to maintain adequate security habitat and food supplies in large blocks of forest of medium and old ages.
Boreal Population (BP)
Concerns are similar to those for the Southern Mountain population except that there is even more intense development in some parts of the range because of multiple resource extraction and protected areas make up a small proportion of areas occupied by caribou. Extent of occurrence has shrunk about 40% from generalized historical distributions in Alberta and Ontario. However, some of the range within historical extent of occurrence was unsuitable for caribou. Range retractions are less in Saskatchewan and Manitoba. Areas of current occupancy may be reduced to less than half of historical distributions.
An estimated 33 000 caribou occur in at least 64 local populations that are scattered over a vast area from the Mackenzie Delta to the coast of Labrador. A major challenge is to maintain connectivity among local populations to ensure gene flow and genetic diversity. The provinces and territory must cooperate in that objective for many populations are inter-jurisdictional.
Most (12) local populations of 19 with trend data are considered to be decreasing in number (Table 3). However, those trend data are available only for the Prairie Provinces and Labrador (Table 2) and represent only about 35% of range occupied by forest-dwelling woodland caribou (S. Carriere pers. comm. 2001). There is much uncertainty about what is happening in the remainder of the range, much of it in Ontario and Quebec. Factors that adversely affect woodland caribou (Table 7) are similar across the range of the Boreal population. Development is intense in the commercial forest, in petroleum producing areas, and in mineral-rich areas. Forestry will have accelerated effects on caribou across Canada as the second pass (cut) is made in ‘two pass’ systems. Most of the forest then will be too young to produce caribou forage unless special provisions are made for caribou within areas of occupancy. If climatic warming continues, summer forage will be reduced in peatlands and fires reduce winter range in peatlands and upland forests.
The Alberta government declared woodland caribou to be threatened in 1985 (Edmonds 1998). Harris (1999) suggested a ranking of threatened for the forest-dwelling ecotype in Ontario. The status of forest-dwelling caribou in other jurisdictions appears to be similar. Concern for the status of woodland caribou has been a factor considered in the expansion of protected areas in B.C., Alberta (Caribou Mountains), Ontario (Duinker et al. 1998), and other provinces and territories.
Kelsall (1984) considered that woodland caribou were secure in the NWT and threatened in Alberta, Saskatchewan, and along the southern fringes of its range in Manitoba, Ontario, and Quebec. Some small local populations and subpopulations in southern parts of the Boreal NEA have disappeared or are likely to. There are examples in all provinces. Many of the boreal populations occur in areas of intense development, which fragments populations and metapopulations, alters predator-prey relationships, introduces parasites, and provides access for hunters. In sharp contrast, forest-tundra ecotypes within COSEWIC’s Boreal NEA are 5-6 times more numerous than forest-dwelling caribou, are not considered to be at risk, and are excluded from designation. Those migratory populations include George and Leaf River in Quebec/Labrador, unnamed local populations primarily in taiga west of James Bay and south of Hudson Bay, Pen Island in Ontario/Manitoba, and the Churchill in Manitoba. We recommend that the forest-tundra ecotype be included in the Arctic NEA or in a new Taiga NEA.
Newfoundland Population (NP)
Recent information suggests an increasing population of approximately 100 000 caribou (Mahoney 2000) an increase of 25% over the previous estimate in 1996 (Mahoney and Schaefer 1996). Of 27 local populations, 18 are larger than 500 individuals. There may be another 10 small local populations whose status is not known. The greatest risk may be overexploitation of range.
Atlantic (Gaspésie) Population
The Centre de données sur le patrimoine naturel du Quebec (CDPNQ) gave the Gaspésie population a status of susceptible (Huot pers. comm. 1997). Crête et al. (1994) suggested that “It would likely be more accurate to classify the Gaspésie caribou herd as endangered rather than threatened.” Its low numbers qualify it for endangered ranking under COSEWIC guidelines.
This population is protected within Quebec's Gaspésie Conservation Park. Even so, the mining industry wanted to modify park boundaries (RENEW 1993). Of concern was the small size of the population, that is, 200 to 250 from 1993 to 1996. Also of concern until 1993 was a low survival rate of calves due to predation by coyotes and bears (RENEW 1993). A Recovery Plan, accepted in 1992 and revised and published in 1994, included recommendations for coyote control, studies of coyote ecology, information on caribou demography, and control of tourist activities. A major goal was to ensure that the population remained above 200 caribou (RENEW 1994). The population may persist with predator control leading to improved calf survival (Crête and Desrosiers 1995). In 1995, a recovery team was disbanded after objectives were achieved (RENEW 1999). However, recent information suggests further declines and a need for continued intensive management including reduced forest operations outside the park (Fournier 2001).
The population is geographically isolated in an island of boreal forest south of the St. Lawrence River and it represents the only caribou in the Atlantic NEA. The small population size and small area of occupation mean that it is susceptible to genetic drift and inbreeding depression and chance extinction by rare climatic events.
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