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
Fire and succession are natural processes that profoundly affect forested caribou range. Fire is necessary to regenerate some plant species including pine. The average fire-return interval or fire cycle is an important statistic for caribou range. It varies from an average of 200-350 years in winter range in B.C. (B.C. Ministry of Forests 1992) to 40-80 years in the southern boreal forest in Alberta and Saskatchewan. Caribou use mature and old-growth coniferous forests in winter because terrestrial and arboreal lichens are most abundant in those forests. In summer, caribou occasionally feed in young stands after fire (Schaefer and Pruitt 1991) or logging (Thomas and Armbruster 1996b). Obviously, caribou have adapted to shift winter range in relation to successional patterns. However, caribou habitats in commercial forests will be seriously degraded after current mature- and old-growth forest is cut and a cutting rotation is established.
Northern Mountain Population (NMP)
Yukon caribou use two contrasting winter habitats. The Chisana, Kluane, Aishihik, and Klaza local populations use alpine ranges, whereas seven populations to the east forage in forests (Kuzyk et al. 1999). A significant difference was found in shoulder height of caribou in those groups.
Caribou spend much of the summer in alpine and upper subalpine range and in winter move down to coniferous forest in lower subalpine and, rarely, to the montane. In Yukon and northern B.C., most caribou winter in areas where snow cover is relatively light (Bergerud 1978, Heard and Vagt 1998). They winter at low elevation in either mature lodgepole pine (P. contorta) or spruce forests where they feed primarily on terrestrial lichens and secondarily on arboreal lichens. Some caribou also winter on high slopes where wind action allows access to terrestrial lichens (Bergerud 1978, Heard and Vagt 1998, Kuzyk et al. 1999). Forestry management recommendations in B.C. include maintaining some old stands, even-aged management, and a mosaic of large harvest units and “leave” areas (Seip 1998). Leave areas are not reserves but are left for future cutting. The average mean fire return interval in the spruce-willow-birch forests in northern B.C. is 200-350 years (range 150-500 years) (B.C. Ministry of Forests 1992).
Southern Mountain Population (SMP)
The SMP in B.C. occurs mostly in alpine and englemann spruce-subalpine fir biogeoclimatic zones (B.C. Ministry of Forests 1992). The west-central metapopulation is in a precipitation shadow where sub-boreal forests of pine and spruce occur at lower elevation (Cichowski 1989). The north-central metapopulation is in a wetter climate where spruce-fir and spruce forests predominate. Both central metapopulations feed primarily on terrestrial lichens. In contrast, the arboreal ecotype in the southern metapopulation of B.C. is obligated to consume arboreal lichens over a thick snow pack (Heard and Vagt 1998). Thus, the two ecotypes of caribou do not conform to COSEWIC NEAs. Two metapopulations (13 local populations) in B.C. and five (one listed by both provinces) in the mountains and foothills of Alberta are the terrestrial-feeding ecotype. In the SMP, they are grouped with 13 local populations in the southern mountains of B.C. that are the arboreal ecotype.
Range use by the arboreal-feeding ecotype (B.C. “mountain caribou”) varies seasonally (Stevenson 1991, Simpson et al. 1997). In early winter, caribou use valley bottoms and lower slopes, and then move to upper slopes and ridge tops after the snow pack deepens and hardens in mid- and late winter. They survive for 6-8 months feeding almost exclusively on arboreal lichens. Those long-strand lichens are predominantly Alectoria sarmentosa and Bryoria spp. In spring, caribou descend to access green vegetation. Pregnant caribou move upwards again in May and usually are found in old forests (Simpson et al. 1997). Forest management recommendations for biodiversity in southern mountains of B.C. include maintaining a landscape dominated by old and mature forest, uneven-aged tree management, small cut blocks, and mature forest connectivity (Seip 1998). Fire is not a major disturbance factor as the mean fire return interval averages 200-300 years in spruce-fir forest (B.C. Ministry of Forests 1992). It is shorter in the Rocky Mountains east of the continental divide and varies with elevation. The result is many “hanging” old-growth forests in the upper subalpine.
In mountain habitat in southern Jasper National Park, Alberta, caribou crater for terrestrial lichens in winter by descending, as snow deepens and hardens, to progressively feed in alpine, upper subalpine, lower subalpine, and, rarely, the montane ecoregion (Thomas and Armbruster 1996a). Some caribou within subpopulations spend part of the winter in alpine areas if feeding conditions are suitable there. They eat variable amounts of arboreal lichens, depending on availability and snow conditions. Perhaps because of isolation (“island effect”), caribou in southern Jasper National Park are smaller than those in the A la Pêche population that summers in northern Jasper National Park and the Willmore Wilderness Park (Brown et al. 1994, Thomas and Armbruster 1996a).
Three local populations (Narraway, Redrock/Prairie Creek, and A la Pêche) generally leave the mountains in October to winter in the foothills, a snow-shadow zone where lichens are abundant (Edmonds and Bloomfield 1984). Feeding is predominantly on terrestrial lichens but short forms of arboreal lichens are consumed (Edmonds 1991). In Alberta’s Rocky Mountains, only very old forests with northern or eastern exposures produce abundant, long-strand arboreal lichens (Thomas and Armbruster 1996a). Edmonds and Bloomfield (1984) provided detailed information on the standing crop of vegetation in range types on winter range in the foothills of Alberta. Preference is for forests older than 80 years and caribou used old forests in late winter when arboreal lichens constituted part of the diet (T. Szkorupa pers. comm. 2001).
Boreal Population (BP)
The woodland caribou of northeastern B.C., east of the Cordilleran Mountains, are considered to live in small, dispersed bands throughout the year, rather than in discrete populations (Edmonds 1991, Heard and Vagt 1998). Similar behaviour may also be the case on the plains in the NWT and on the Shield in Saskatchewan, Ontario, and Quebec. However, further study may reveal discrete populations. Caribou in northern Alberta showed significant preferences for both bogs and fens with low to moderate tree cover and they avoided marshes, uplands, heavily forested wetlands, water, and areas of human use (Brown et al. 2000a). The Bistcho and Caribou Mountains populations (Fig. 1 in Dzus 2001) are associated with elevated terrain classified as boreal subarctic (taiga). Canopies of open black spruce (P. mariana) and white spruce (P. glauca) occur in and around peatlands where terrestrial lichens are abundant. Elsewhere, peatlands are preferred habitats of caribou (Bradshaw et al. 1995, Stuart-Smith et al. 1997, Rettie and Messier 1998, Anderson 1999). Their use by caribou generally is attributed to an attempt to avoid predators (Stuart-Smith et al. 1997, Rettie and Messier 1998, James 1999, James and Stuart-Smith 2000). However, peatlands are also important food sources (Thomas and Armbruster 1996b), have fewer parasitic insects, and create some separation from other ungulates. Predators cause direct mortality and may transmit harmful parasites. Some peatlands and adjacent black spruce and tamarack forest produce terrestrial and arboreal lichens and provide year-round habitat requirements. In northeastern Alberta, calf survival was related to the size of fens in home ranges (Stuart-Smith et al. 1997). Burns are less of a factor in large peatlands south of the shield, as indicated by considerable old growth black spruce around their periphery and within them on islands of elevated terrain.
Caribou range in Saskatchewan south of the Precambrian Shield (Thomas and Armbruster 1996b, Rettie and Messier 1998) is similar to that in northeastern Alberta where populations are associated with fens and adjacent coniferous forests (Stuart-Smith et al. 1997). Data from satellite collars indicate a distinct preference for peatlands (99% of locations, Stuart-Smith et al. 1997) and peatlands and black spruce forests (Rettie and Messier 2000). In contrast, there was relative avoidance of young forests originating from fire or logging.
In the Boreal Shield in Saskatchewan, peatlands generally are small and associated with margins of numerous lakes and intervening streams. Such range is subject to large burns at intervals of 50-100 years, which affects numbers and distribution of caribou. Caribou are more exposed to predation on the shield but moose and resident wolf densities may be relatively low there (Darby et al. 1989). In Quebec and central Manitoba, caribou showed fidelity to areas used at calving and in summer but not to winter locations (Paré and Huot 1985, Brown et al. 2000b). The majority of animals in the Manitoba study wintered near their summer ranges, though short movements to wintering locations were also noted. Caribou used peatland complexes and generally avoided clear-cut areas and aspen/poplar-dominated sites.
Caribou winter range in northwest Ontario typically includes open coniferous forest over sandy soils, which produces an abundant ground cover of Cladina spp. lichens (Harris 1999). Sites used in winter could be predicted by combined use of forest resources inventory data and Landsat imagery (Antoniak and Cumming 1998). Another study of habitat use in northwestern Ontario, using satellite telemetry, found that caribou selected habitats containing conifer cover and avoided disturbed areas and shrub-rich habitats (Hillis et al. 1998). Range in northeastern Ontario is wetter as indicated by an ecoclimatic map (Ecoregions Working Group 1989). Caribou in the Lac Bienville, Caniapiscau, Lac Joseph, and Red Wine Mountains occupied open lichen woodlands (taiga), wetlands (peatlands), and tundra (Brown et al. 1986). Black spruce and tamarack were the dominant tree species.
Fire is the major natural disturbance force in boreal forests. Average fire return intervals of only 20 to 60 years are reported for Alberta, Saskatchewan, Manitoba, and western Ontario and 100 and 500 years for Northern Quebec and Labrador (e.g., Table 5 in BQCMB 1994). Only about half of a study area in Manitoba contained forests older than 50 years (Schaefer and Pruitt 1991). Fire suppression is considered to have delayed natural fire succession, though there are contrary views. In 1995, fire in northeastern Alberta and central Saskatchewan swept through all cover types including recent logged sites and young plantations.
Newfoundland Population (NP)
Caribou use a mixture of boreal and taiga coniferous forest with some shrub land, peatlands, and ‘barrens.’ Caribou in the Corner Brook Lake area preferred barrens, mature and over-mature forests, and avoided scrub, bog, and immature forest (Snow and Mahoney 1996).
Atlantic (Gaspésie) population (AP)
Range types used by caribou were grouped into alpine, mature spruce, mature fir, immature forest, and hardwood (Ouellet et al. 1996). Patches of stunted fir and white spruce occurred on the tundra above 915 m. Mature fir cover along with white spruce in the subalpine was important winter range. Critical summer habitat included tundra of Mont Albert and Jacques-Cartier Mountains (Crête et al. 1994). Logging, which occurred in the park until 1977, removed part of the forest habitat including arboreal lichens.
Monitoring trends in quantity and quality of the food component of habitat is important but very difficult. Generally it is ignored with an assumption that caribou populations are far below the ‘carrying capacity’ of the vegetation. Carrying capacity generally refers to food resources for caribou but it should also include other ecological variables such as forage accessibility, space to reduce contact with predators, and specific requirements such as calving and post-calving areas and relative refugia from predators, insects, and thermal stress. That is, distinction should be made between food carrying capacity and ecological carrying capacity. Relative abundance of food may be much lower than absolute abundance because of the effects of snow and ice, predators, insects, and human activities. Caribou usually do not need large areas for feeding but need space to reduce contact with predators and they need certain types of habitats to lessen other limiting factors.
Criteria to estimate food limitations currently are indirect. The most common measure is pregnancy and parturition ‘rates’. However, early loss of calves and good summer range can result in high conception rates even though nutritional restrictions in winter may result in weak calves with high mortality from predation or other factors. Consequently, seasonal nutritional deficiencies can be masked. Reproductive pauses every few years in individual forest-tundra caribou suggest a gradual decline in condition after successive pregnancies (Dauphiné 1976, Cameron 1994). It is difficult to determine if declines are food and energy-related, are due to predation, or are caused by an interaction of those factors plus others such as hunting. Furthermore, there may be a lag between habitat deterioration and decline of a local population.
There is incomplete information even on total occupied range of most caribou populations. Usable (“effective”) habitat can be calculated once the effects of roads and disturbance are known. For example, 28% to 70% (average = 48%) of study areas may be avoided by caribou (Dyer 1999). Such percentages do not include habitat loss and degradation from logging and other developments.
Results from disturbance studies should be viewed with caution. Caribou at low densities and well below the carrying capacity of their range are likely to withdraw from industrial activities. Whether they have to move and whether their fitness is compromised is speculative. There is a need to measure behavioural responses to gradations of disturbance, accommodation over time, and effects on demographics. If sources of mortality such as wolf predation and hunting are managed, caribou may be able to co-exist with well-managed developments.
Maps of forestry leases across Canada (Equinox 1991, Peterson et al. 1998) and particularly in relation to extent of occurrence (potential distribution) and area of occupancy (currently used range) of forest-dwelling populations reveal the potential for profound changes to caribou habitat. Extent of occurrence is more suitably termed area of potential occurrence and data sources should include cover-type analysis and historical information.
Logging and fire can concentrate caribou (Smith et al. 2000). After one ‘pass’ of clear cutting, there is still up to 50% mature and old growth left. After the second pass there is virtually no old forest left unless there are reserves specifically for caribou or other values. After one complete rotation in a two-pass system there may be only 10-20% in a mature class at any one time and it is just over rotation age. No old growth forest may remain except that around peatlands or at sites commercially non-productive. In terms of caribou habitat, a mature forest may be inferior to an old-growth forest but much depends on tree species, soil, moisture, succession rate, slope and aspect, and how the surface was treated during and after logging (Thomas and Armbruster 1996b). In Alberta the second pass is permitted 15-25 years after the first. That timing is supposed to provide adequate cover for wildlife in the young stand but it is far too short to sustain caribou habitat. A suitable interval between passes to sustain adequate caribou habitat may be 30-60 years depending on cover type, local site conditions, and forestry prescriptions.
Northern Mountain Population
Habitat concerns expressed by jurisdictional representatives ranked below non-regulated hunting (70% of local populations) and predation (62% of populations). Most local populations are quite isolated from human activities and forestry operations are a concern for only 35% of the populations and connectivity for 37% (Table 7). Lack of available habitat is of high or medium concern for 32% of the local populations, with wildfire a concern for 56% of 37 populations (Table 7). Seasonal use by caribou of low elevation range in winter conflicts with forestry operations (Cichowski 1989, Stevenson 1991). Oil and gas activity is expected to increase.
Southern Mountain Population
Caribou disappeared from 15% (Seip and Cichowski 1996), 20% (Spalding 2000), or 40% (MELP 2000) of historical range in B.C. Range reduction was proportionally greatest in the Southern Mountain population. Hunting was suggested as the main cause of range retraction in central and southern parts of the province. Predation and forestry operations are now the main concern (Table 7). Access/disturbance and forestry operations are of high or moderate concern for 94% and 90%, respectively, of the 30 local populations. Loss of connectivity and lack of available habitat are concerns for 73-74% of populations. Those are high numbers considering that three of the populations are in national parks and several populations are partially in protected areas (Appendix 2b). Forest fire was a concern for 47% of populations.
Use by caribou of low elevation range in winter conflicts with forestry operations (Stevenson 1991). Timber cuts are being made at higher elevation as the first cut is completed in valley bottoms and on lower slopes. Fragmentation of range is a serious consequence of forestry and other developments. In the Purcell Mountains, caribou frequented areas containing at least 40% suitable habitat at fine (250 ha) and coarse (5000 ha) scales (Apps and Kinley 1998). One accepted hypothesis is that increases in moose numbers on caribou range, as a result of re-colonization abetted by logging, has resulted in more wolves and higher caribou mortality (Seip 1992). Thus, predation is a concern for 94% of local populations (Table 7).
Oil and gas activity is increasing in the Northwest Territories and northeastern B.C., where little is known about local populations of caribou. Historical range in Alberta was greater than present (Edmonds 1991) though distributions were undoubtedly patchy because, east of the foothills, the majority of cover is deciduous and mixedwood forest. Caribou range has been lost, degraded, and fragmented by petroleum activities, logging, mining, hydroelectric developments, and associated linear structures. In Saskatchewan, road development associated with forestry and mining resulted in range fragmentation and increased hunting mortality (Rock 1991, 1992). Caribou range in the commercial forest is changing rapidly as forestry operations are widespread across most of the boreal forest (Peterson et al. 1998). Concerns for caribou relate to large reductions in proportions of medium and old-growth coniferous forests, increased access and fragmentation, altered predator-prey relationships, a meningeal parasite harboured by white-tailed deer (O. virginianus) east of Saskatchewan, and climatic change at regional and local scales.
Landscape-level forest management guidelines in B.C. (Seip 1998) and Ontario (Armstrong 1998) attempt to emulate, to some extent, disturbance caused by fire. In Ontario, large leave blocks should reduce populations of moose, deer, and associated wolves and also reduce access by predators and human hunters. Whether such recommendations are widely instituted, in the light of considerable opposition, remains to be seen.
Newfoundland Population (NP)
Commercial logging in summer disturbs caribou (Chubbs et al. 1993), though benefit is derived from clearings where caribou obtain some relief from insects.
Atlantic (Gaspésie) Population
Habitat in the Gaspésie Park was modified by fire, insect infestations, and logging. There is little use of young stands by caribou and it was recommended that logging cease in the park (Ouellet et al. 1996).
Forested lands in Canada comprise 418 million hectares of which 235 million hectares (56%) is considered to be commercial forest (CCFM 2000a). Forest-dwelling caribou occur mostly in softwood forests that comprise 67% of forested lands in Canada. The largest numbers of forest-dwelling caribou occur in Newfoundland and Yukon where, respectively, 91% and 79% of forests are classified as softwood. Ownership of forested lands in 2000 in Canada was 71% provincial, 23% federal, and 6% private (CCFM 2000a).
Protection is afforded woodland caribou and their range by protected areas, wildlife acts and regulations, policy and accords, forestry regulations and standards, and species-at-risk legislation. Protected area within Canadian forests was estimated at 7.6% in 1995 and 8.4% in 1999 (CCFM 2000b). They also serve as important controls for studies that attempt to assess the effects of developments in adjacent areas.
Information was gathered from jurisdictions on proportions of local populations (numbers and occupied range) that were in protected areas such as parks and wilderness areas (Appendix 2). Caribou distributions overlapped about 60 protected areas in B.C.; however, land use plans on adjacent areas were considered to be most important for caribou conservation. For example, protected areas can safeguard habitat but restrict management options such as reducing prey species to manage numbers and distribution of predators.
In the last decade, several initiatives at international, national, and provincial/territorial scales have set guidelines for sustainable forest practices that will help conserve caribou. Included are the Montreal Process, criteria and indicators of the Canadian Council of Forest Ministers (CCFM), provincial policy, criteria and indicators, and certification at international and Canadian scales. The Montreal Process Working Group, consisting of 12 countries, adopted 7 criteria and 67 indicators (CCFM 2000a). In 2000, the CCFM reported progress on 6 criteria, 22 elements, and 83 indicators established in 1997 (CCFM 2000b). Several provinces, notably Quebec, Ontario, Saskatchewan, and Newfoundland-Labrador have developed their own indicators. In 1999, the Senate Sub-Committee on the Boreal Forest provided management guidelines. It recommended three categories of management: intensive for timber (20%), multi-use (60%), and protected (20%).
Forest industry standards include the international Forest Stewardship Council (FSC), the International Organization for Standardization (ISO), and the Canadian Standards Association (CSA). The Canadian standard for sustainable forest management was developed in 1996 in response to growing public opposition to clear-cut logging. The CSA requires that six criteria be addressed including conservation of biological diversity. That provision should help to conserve caribou within forest management areas. It also specifies adherence to 21 “critical” elements in the CCFM criteria and indicators framework (CCFM 2000b) such as ecosystem diversity, species diversity, and genetic diversity.
Certification is not legally required of companies but is driven by the marketplace. By 2003, one retailer will not sell wood products from “endangered areas” and will give preference to wood from certified operations. Another would not sell wood from “ancient forests or other high conservation values forests” unless the forest areas were certified (CCFM 2000a). As of May 31, 2000, certification (mostly ISO) was obtained for 16 million ha (13%) of 120 million hectares under active management (CCFM 2000a). An estimate is that, by 2004, 72 million hectares (60%) of managed forests will be certified.
All jurisdictions have wildlife acts and regulations that are used to close hunting, close hunting on certain road corridors (e.g., Alberta and Saskatchewan), establish limited entry hunts of specific sex and age classes, prohibit night hunting, etc. There is limited recreational hunting of large local populations of forest-dwelling caribou in Yukon. In B.C., there are limited entry hunting and open seasons for mature bulls (minimum of five terminal tines). The same restrictions apply to six local populations in the central metapopulations of COSEWIC’s Southern Mountain population. There is limited hunting in Quebec (Table 9) where there is overlap in winter distribution of forest-tundra and forest-dwelling ecotypes.
There is a trade-off between giving special consideration to individual species at risk versus an ecosystem approach with emphasis on preserving biodiversity. Both approaches are required. Not all species can be accommodated, hence the ecosystem approach. Nevertheless, some species will require specific management and, if wide-ranging and representative of an ecosystem type, can provide habitat for other species. In that context, caribou are an indicator species in Saskatchewan and a feature species in Ontario.
It will be difficult to show that habitat per se is limiting a local population of caribou unless there is agreement on minimum viable population size combined with an average minimum area required per caribou. Ecological carrying capacity should be estimated and projected decades into the future based on land-use plans. Generally, indirect effects of developments, such as increased predation and hunting, initially cause populations to decline in number (e.g., Bergerud 2000).
In all provinces (Maritimes grouped) there are Conservation Data Centres. They all use common criteria formulated by The Nature Conservancy, an international organization, to evaluate species at risk (Table 10). The southern metapopulation in B.C. is Red Listed by the B.C. Conservation Data Centre (Hatter 2000). Although Manitoba, Ontario, and Quebechave endangered species acts they have not listed caribou. Other provinces/territories list endangered and threatened species in their Wildlife Acts or other legislation. In Ontario, a Committee on the Status of Species at Risk has established criteria for population selection and species designation (Harris 1999).
There is some protection from acts, codes, plans, regulations, and guidelines by government forestry agencies that relate to caribou habitat. Other departments and agencies are involved. For example, in 1991, 1994, and 1996, Alberta Energy published procedural guides for oil and gas activity on caribou range (Dzus 2001). The 1991 guidelines state that: Petroleum and natural gas exploration and development activities can occur on caribou range, provided the integrity of the habitat is maintained to support its use by caribou. Most forestry operations are conducted on crown land where governments can make changes through long-term (e.g., 20-year) lease agreements with forestry companies.
Also relevant to caribou conservation are federal, provincial, and territorial legislation, regulations, and policies regarding Aboriginal people and treaty rights. In all, 286 forest management plans encompass 726 518 ha on some of the 2 394 Indian Reserves in Canada (CCFM 2000a). Consultation with First Nations will be essential for their local knowledge and to reduce hunting of caribou made accessible because of roads, seismic lines, and other linear developments. Increases in numbers of other large ungulate species after logging should ensure alternative meat sources.
On the positive side, over the past decade, considerable knowledge of caribou distributions and ecology has been acquired. In many areas there is sufficient knowledge to sustain caribou and limited development. The results of scientific research and other forms of knowledge only lack application. Research results should be presented in a form that can be applied by forest companies and others with power to make changes. Progress must be made towards implementation of current knowledge.
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