Woodland caribou (Rangifer tarandus caribou) COSEWIC assessment and status report: chapter 7
Distribution
Caribou and reindeer are indigenous in arctic, subarctic, and boreal biomes (Banfield 1961, Røed et al. 1991). Woodland caribou extend into Alaska and a short distance into northwestern U.S.A. The range of the trans-boundary Chisana population is mostly in Alaska. It was listed at 850 individuals in 1993 (Valkenburg et al. 1996) and 325 in 1999 (P. Valkenburg pers. comm. 2000). The South Selkirks population, which ranges in B.C., Idaho, and Washington, is estimated at only 35 individuals in 2002 (I. Hatter pers. comm. 2002) about the same as in 1980 (Williams and Heard 1986). Caribou occurred in most of the northern states in the 19th century (Zager et al. 1996). Transplants of caribou from Quebec to Maineand Wisconsin failed because of a parasitic meningeal worm (Dauphiné 1975, Bergerud and Mercer 1989). Therefore, the subspecies caribou is essentially endemic in Canada.
Other free-roaming woodland subspecies in the world are the European forest reindeer, R. t. fennicus. They were estimated at 600 individuals located on the border between Finland and Russia (Nieminen 1980). There are perhaps 195 000 wild forest reindeer in Siberia (Liakin and Novikov 1999) referred to as R. t. valentinae (Gruzdev and Davydov 2001).
Forest-dwelling woodland caribou occur in five of the eight NEAs recognized by COSEWIC (Fig. 3) and 11 of the 16 ecozones on the Ecozone Map of Canada (Ecological Stratification Working Group 1996, National Atlas of Canada 1999). They occur in all jurisdictions in Canada except Nova Scotia, New Brunswick, Prince Edward Island, and Nunavut. Subspecies dawsoni, a peripheral relic, disappeared from the Queen Charlotte Islands about 1935. A reintroduction of 51 caribou in 1968 and 1969 to northern Cape Breton Island failed presumably because of meningeal worm (Dauphiné 1975).
Range reductions of up to 40% were reported for B.C. (MELP 2000, Spalding 2000) and Ontario (Darby et al. 1989). Only about 39% of the generalized maximum historical range in Alberta (Edmonds 1991) is occupied (Fig. 3 in Dzus 2001). Forest-dwelling caribou are associated with large peatlands and coniferous forest cover. Undoubtedly there were large gaps in the historical occurrence where cover was deciduous and mixed forests. Range retractions from historical distributions appear to be proportionally smaller in Saskatchewan and Manitoba but percentage reductions are not available. In eastern Canada, the southern boundary shifted northward during the 19th and 20th century. Formerly, caribou extended into the northern New England States and New Brunswick, Nova Scotia, and Prince Edward Island (Kelsall 1984). Further range retraction across Canada is likely as small local populations disappear along the southern periphery of the range.
The distribution maps of forest-dwelling woodland caribou are based on data received from each jurisdiction in 2000 and 2001. Current extent of occurrence (Fig. 4) has not changed much since Kelsall's review in 1984 but considerable progress was made in delineating areas of occupation (Fig. 5). Enough is known about caribou habitat requirements to estimate historical occurrence using forest cover and wetland data.
Topography, climate, and related winter feeding habits of caribou divide the Cordilleran into two ecotypes of caribou (Bergerud 1978). In the north, snow depths are moderate and caribou feed primarily on terrestrial lichens. In the southern mountains, deep snow causes caribou to eat long-strand arboreal lichens. A third ecotype, boreal, occurs east of the mountains (Heard and Vagt 1998). Alpine and forest winter-feeding types are recognized in Yukon (Kuzyk et al. 1999). The Northern and Southern Mountain boundary in B.C. is approximately between spruce-willow-birch and the englemann spruce-subalpine fir (P. englemannii-Abies lasiocarpa) biogeoclimatic zones (B.C. Ministry of Forests 1992).
Northern Mountain Population (NMP):
In Yukon, 22 local populations of caribou in the NMP occupy much of the territory south of latitude 65o N. Two NMP populations (Hart River and Bonnet Plume) overlap the winter range of the Porcupine herd of barren-ground caribou. One declining population, the Chisana, straddles the Yukon-Alaska border (Farnell et al. 1998). Four local populations occupy ranges extending to the east slope of the Mackenzie Mountains in the NWT. Another two are also listed by B.C. but six may be transboundary. After accounting for population overlap, 36 local populations constitute the NMP in Yukon, NWT, and northwestern B.C. (Appendix 1a). Caribou distribution in the NMP is little reduced from historical ranges. Gaps between local populations tend to be wider in B.C. than in Yukon. The range of two populations extends eastward a short distance into the Boreal and three overlap the Southern Mountain population (Caribou in British Columbia, draft map 2002, I. Hatter, pers. comm.).
Southern Mountain Population (SMP)
In B.C., three metapopulations of caribou are recognized in the SMP. They are the isolated west central (five local populations), the north central (eight local populations with one overlapping the Northern Mountain and one overlapping Alberta), and the southern (13 local populations or subpopulations) (Hatter 2000 and pers. comm. 2002, Appendix 1b). The first two metapopulations are the terrestrial feeding ecotype and the third, the southern, comprises what are termed “mountain caribou” (Heard and Vagt 1998). At a national scale, they are better described as the arboreal-feeding ecotype because “mountain caribou” in Alberta eat primarily terrestrial lichens in winter. The Selkirk boundary population, shared with Idaho and Washington, received transplants totalling 60 caribou to 1995 (Compton et al. 1995) and an additional 53 in 2000 (J. Quayle pers. comm. 2002). Source populations before 1995 were the Revelstoke and the Itcha-Ilgachuz. Four tagged caribou emigrated from Washington and Idaho to the South Purcell’s population in B.C. (Kinley and Apps 2001). The Selkirk and South Purcell’s populations at the southern periphery of the range contain only 35 and 20 caribou and may disappear because habitat changes cannot be reversed in the short term.
Five local populations in the Rocky Mountains and foothills of Alberta are included in the SMP though they rely primarily on terrestrial lichens in winter (Edmonds and Bloomfield 1984, Thomas et al. 1996). They are equivalent in feeding behaviour to the “northern” ecotype in B.C. (Edmonds 1991). The three migratory local populations that summer in the Willmore Wilderness Park, northern Jasper National Park, and adjacent B.C. (Edmonds 1988, Brown and Hobson 1998) could be considered a metapopulation with populations that breed and winter in three separate areas in the foothills. They are considered to be distinct local populations with overlapping summer range, namely the Narraway (Belcourt in B.C.), Redrock/Prairie Creek, and A la Pêche (Brown and Hobson 1998, Dzus 2001). One small population, Little Smoky, borders the SMP. It may be a relic from the southern clade and is considered a forest (boreal) population (Edmonds 1988). Local people detected a difference between two types of caribou that wintered near the Little Smoky River (Edmonds and Bloomfield 1984).
A population with two or three subpopulations exists in southern Jasper National Park and the Whitegoat Wilderness Area to the south. The western subpopulation extends to the Fraser River in B.C. Another isolated population in northern Banff National Park and the Siffleur Wilderness Area (Brown et al. 1994, Brown and Hobson 1998) apparently has declined from 20-50 caribou in 1990 to only a few in 1998 (Mercer pers. comm. 2001). Thus, the southernmost population in Alberta is likely to disappear. In summary, there are 30 local populations in the SMP, excluding the sedentary Little Smoky population.
Boreal Population (BP)
This ‘ecographic’ population covers a huge area from the Mackenzie Mountains in the northwest to southern Labrador in the east and as far south as Lake Superior. The range of the BP in the NWT was enlarged with recent information (Fig. 5) (A. Gunn pers. comm. 2001). No discrete local populations are known for the NWT or northeastern B.C. (Heard and Vagt 1998). Densities are low and there are likely to be large gaps in occupation in what is mapped as potential extent of occurrence. In winter, migratory forest-tundra caribou enter outer portions of the ranges in the NWT.
With the exception of the isolated and precarious Little Smoky local population in the south, the boreal ecotype of woodland caribou occurs north of 55o N in Alberta, (Edmonds 1998, Dzus 2001). The current area of occupation (Fig. 3 in Dzus 2001) is only about 39% of the area north of a line showing historical occurrence in Alberta (Edmonds 1991). However, current extent of occurrence, as shown by observations of caribou mapped in Dzus (2001), is perhaps 50% larger than area of occupation. Enclosing observations with smoothed distributions increases occurrence to about 58% of historical distribution. If unsuitable habitat was removed from the map of historical range, the reduction may approach 40%, similar to that in B.C. and Ontario. Caribou have recently abandoned range or disappeared from parts of Little Smoky, Calahoo Lake, Pinto/Nose Creek, Deadwood, and Slave Lake (Dzus 2001).
After radio collaring more than 300 caribou in the Boreal population in Alberta, 11 local populations were recognized. Tentatively, they can be grouped into three metapopulations currently containing three, two, and five or six local populations (Fig. 1 in Dzus 2001). There was no movement of radio-collared individuals among the local populations with the exception of the east and west Athabasca populations (Dzus 2001). They may be subpopulations divided by the Athabasca River. Analysis of distributions of radio-collared caribou in four study areas revealed that habitat polygons containing more than 30% bogs were selected and those containing more than 50% non-peat were avoided by caribou (Schneider et al. 2000).
In Saskatchewan, little was written on woodland caribou distributions up to 1987 (Trottier 1987, 1988a, 1988b). Starting in 1992, 36 radio collars were placed on caribou in four local populations in the Boreal Plain (commercial forest zone) and on another that in summer ranged on the Boreal Shield (Rettie et al. 1998, Rettie and Messier 1998, Rettie and Messier 2000). The populations are considered to represent relic, isolated populations of what historically was a more-general distribution (Rettie and Messier 2000).
After work in the 1990s, 18 local populations were mapped (Fig. 5) in 2000 within a generalized extent of occurrence (Fig. 4). Only in the past few years have surveys been conducted on forest-dwelling caribou in the Boreal Shield of Saskatchewan (Godwin and Thorpe 2000). Data are summarized by three ecoregions (Godwin and Thorpe 2000) because not enough is known about local populations except for four located in the Mid-Boreal Ecoregion (Boreal Plains Ecozone) and one in the Churchill River Upland (Taiga Shield) (Rettie and Messier 2000). Those five local populations are considered to be a metapopulation (Rettie and Messier 2000). A map produced in 2001 shows seven geographic areas of occupancy with some sightings or tracks between them (A. Arsenault pers. comm. 2001). The distribution in Saskatchewan was expanded northward from that shown by Kelsall (1984) to include southern Reindeer and Wollaston lakes and north of Lake Athabasca. Densities around Lake Athabasca are assumed to be extremely low because much of the range has burned in the last 50 years (BQCMB 1994). In winter, forest-tundra caribou in the Beverly population invade that area periodically. There are at least 21 local populations when the two maps are combined.
In Saskatchewan, as in B.C. and Alberta, some of the small local populations or subpopulations along the southern periphery of the range have disappeared or are in a precarious state (Trottier 1988a, Rock 1992). Examples are occurrences near Kazan Lake, Waterhen-Keeley-Canoe Lakes, Sled Lake, Deschambault Lake, northeast Prince Albert National Park, east and south of Montreal Lake, Little Bear Lake, Candle Lake, White Gull Lake, Creighton, Pasquia Hills, and Woody Hills (Trottier 1987, Rock 1992, Godwin and Thorpe 2000, J. Rettie pers. comm. 1998).
In Manitoba, the tillable southern portion of former woodland caribou range is no longer occupied (Johnson 1993). However, caribou continue to occupy most of the traditional range (Larche 1996) and 14 local populations are mapped. All are in a southeast to northwest band across the province except for the Nelson-Hayes population in the northeast. Its distribution overlaps that of the Pen Island population of forest-tundra caribou (Abraham and Thompson 1998). Some caribou may have emigrated from the Nelson-Hayes population to the expanding Pen Island population (Cam Elliott pers. comm. 2002).
In Ontario, the forest-dwelling ecotype occurs in a band below the forest-tundra ecotype (Harris 1999). The ecotype boundary cuts across the centre of the Hudson Plain ecozone. That boundary may change when information is obtained on caribou west of James Bay. The coastal tundra belt combined with the sub-arctic (taiga) lichen belt approximates the Hudson Plain Ecozone in Ontario (Darby et al. 1989). Local populations of unknown genotype occur at Cape Henrietta Maria, Shagamu, and Hawley Lake (Harris 1999). Since the turn of the century, when woodland caribou in Ontario were found as far south as Lake Huron, the southern edge of occupied range receded northward to about 50o N. (Darby et al. 1989). The cause was loss of groups of caribou in the commercial forest (Racey and Armstrong 2000). At least six small relic populations occur south of the line of semi-continuous distribution. These local populations are Slate Islands (Butler and Bergerud 1978), Pic Island (Ferguson et al. 1988), Pukaskwa (National Park), Caramat, Flanders Township, and Hagarty Road (Darby et al. 1989). In addition, two of three translocated populations may persist.
In Quebec south of 490 N, the Val D'Or and Grands Jardins “sedentary” populations number about 40-90 and 103 individuals, respectively. The Grands Jardins population was extinguished about 1926. From 1966 to 1972, it was restocked with 82 caribou (Vandal and Barrette 1985) raised in captivity.
Local populations of forest-dwelling caribou in the boreal forest and southern taiga between about 510 N and 540 N include Lac Bienville, Caniaspiscau, La Forge, Nitchicun, Opiscoteo (Belangier and Le Henaff 1985), and Lac Joseph (shared with Labrador). Even though radio collars were put on some of them (Lac Bienville, Caniapiscau, Lac Joseph) in the early 1980s, their ranges are poorly defined. They are thought to be essentially discrete populations (Brown et al. 1986). The population status of those sedentary caribou is complicated by invasion in winter of thousands of migratory caribou mostly from the George River population (Brown et al. 1986, Couturier 1996). The expanding Leaf River population also overlaps in winter with sedentary caribou in western Quebec.Other local populations may occur between Waskaganish and Nemiscau east of James Bay (Caribou Quebec 2000) and the McPhaden River west of Schefferville (Brown et al. 1986). Current studies should clarify the status of caribou in Quebec.
In Labrador, the Red Wine Mountains population occurs in the southern taiga (Brown and Theberge 1985, Schaefer et al. 1999), whereas the Mealy Mountain and Lac Joseph (formerly Waco) populations straddle boreal and taiga ecozones (Schaefer 1997).
In summary, to date more than 64 local populations of forest-dwelling caribou have been identified in the Boreal NEA (Table 2). That number will increase as individuals in more populations are radio collared, distributions are delineated, and local populations become isolated by human developments and activities. Additional local populations are likely to be identified in northern Saskatchewan and in the bands of general occurrence in Ontario and Quebec. More-or-less discrete local populations occur in Alberta, Saskatchewan, and Manitoba where populations often are associated with large peatland complexes (Stuart-Smith et al. 1997, Rettie and Messier 2000, Brown et al. 2000b, Dzus 2001). Peatlands also occur in the boreal forest of Ontario but islands and lakeshores are also used as summer range by small groups of caribou that seemingly range over large areas (Armstrong et al. 2000, Racey and Armstrong 2000). This may also be true for forest-dwelling caribou on the Precambrian Shield in Saskatchewan, Manitoba, and Quebec.
Newfoundland Population (NP)
Woodland caribou of Newfoundland are found on the Main Island and offshore islands in 15 natural and 22 introduced populations (Mahoney 2000, Doucet pers. comm. 2001). Data are available for the natural populations and for 12 of the introduced populations. After a sharp decline in the early 1900s, the populations became centred in the most inaccessible parts of their range. In the last few decades, however, the range has expanded gradually and woodland caribou now occupy most of their historic range (Mahoney and Schaefer 1996).
Atlantic (Gaspésie) Population (AP)
This isolated population is the only one south of the St. Lawrence River. Its distribution is largely restricted to Gaspésie Conservation Park (Crête et al. 1994, Ouelett et al. 1996). The population historically occupied coniferous forest in Quebec, New Brunswick, Nova Scotia, Prince Edward Island, Maine and northern New Hampshire, Vermont, and New York. It should be genetically distinct from all other woodland caribou because of long isolation and small numbers.
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