|Dean Biggins, U.S. Fish and Wildlife Service, Digital Library System|
Rangifer tarandus caribou (Gmelin) woodland caribou
Rangifer tarandus dawsoni Thompson-Seton Dawson caribou (presumed extinct)
Rangifer tarandus groenlandicus (L.) barren ground caribou
Rangifer tarandus pearyi J. A. Allen Peary caribou
Peripheral populations of caribou within the United States have been
eradicated. Populations that occurred from Minnesota to Maine are now presumed extinct
[27,49]. Woodland caribou were exterminated from Minnesota by 1942 . Caribou
disappeared from New York before 1800, from Vermont by 1840, from New Hampshire
around 1865, and from Maine by 1916 except for a sighting in 1946. Caribou disappeared from Wisconsin by 1850, from Michigan in 1931, and
from Minnesota by 1955 .
Caribou are considered part of the climax biota because of their dependence on late successional forests and associated lichen forage [68,101]. Caribou use old-growth and mature coniferous stands across their range [80,97]. Woodlands with sparse overstories of black spruce-paper birch (Picea mariana-Betula papyrifera) or jack pine (Pinus banksiana) and a dominant ground cover of lichens are heavily utilized [57,79,101]. Caribou frequent peatlands, bogs, muskegs, lake shores, and other wetland and riparian areas [37,61,97].
Alaska: Black spruce and white spruce (Picea glauca) in pure or codominant stands with lichen-moss understories are heavily utilized in Alaska [57,103]. Sedge meadows dominated by water sedge (Carex aquatilis), rock sedge (C. saxatilis), and tall cottonsedge (Eriophorum angustifolium) provide year-round forage. Barren ground caribou also utilize willow stands dominated by feltleaf willow (Salix alaxensis), Barclay's willow (S. barclayi), grayleaf willow (S. glauca), tealeaf willow (S. pulchra), and Richardson's willow (S. richardsonii). Grasslands dominated by rough fescue (Festuca altaica) with birch (Betula spp.) and willow (Salix spp.) associates are frequently utilized. Bog birch (Betula glandulosa) dominates some landscapes at 3,000 to 4,000 feet (900-1,200 m), with tealeaf willow and rough fescue codominant at 3,000 to 3,500 feet (900-1,100 m) . Mountains <7,900 feet (2,400 m) in Denali National Park are characterized by shrub tundra dominated by birch and willow [1,18] and alpine zones dominated by sedges (Carex spp.) . High-elevation tundra in Denali National Park is characterized by mountain avens (Dryas spp.) . A mosaic of spruce (Picea spp.)-dominated forests, cottonsedge (Eriophorum spp.)-dominated tundra, and riparian areas with mixed spruce and willow exists below 2,600 feet (800 m) in Denali National Park [1,18].
Canadian Arctic Archipelago: Wilkinson and others  identified 5 distinct caribou habitats in the archipelago. Barren uplands are characterized by arctic dryad (D. integrifolia), sedges, willows, grasses, and lichens. Sedge meadows are dominated by water sedge (C. aquatilis var. stans), white cottonsedge (Eriophorum scheuchzeri), and Fisher's tundragrass (Dupontia fisheri). Sand dune habitats are dominated by feltleaf willow, polar willow (Salix pseudopolaris), dwarf fireweed (Chamerion latifolium), pale Indian paintbrush (Castilleja pallida), and grasses. Tundra tussocks are characterized by willows, arctic dryad, sedges, and grasses. Lakes and lake edges are dominated by water sedge, pendantgrass (Arctophila fulva), and false semaphoregrass (Pleuropogon sabinei) .
Idaho, Washington, and British Columbia: Western hemlock-western redcedar (Tsuga heterophylla-Thuja plicata) communities are important in to woodland caribou during autumn and early winter [6,36,102]. Mixed stands of old growth Engelmann spruce-subalpine fir (Picea engelmannii-Abies lasiocarpa) are preferred in late winter [6,36]. Caribou occasionally use interior lodgepole pine (Pinus contorta var. latifolia) forests [24,36].
Alberta: Black spruce-tamarack (Larix laricina) dominates lowland fens and bogs, while uplands are dominated by white spruce-jack pine-quaking aspen (Populus tremuloides) .
Northwest Territories, Saskatchewan, and Manitoba: Dominant species include black spruce, white spruce, and jack pine [77,80,89,99,101]. White birch, tamarack, quaking aspen, and balsam poplar (Populus balsamifera) are common associates [77,80,89,99]. Jack pine is abundant on some upland sites. Dominant shrubs on upland sites include mountain cranberry (Vaccinium vitis-idaea), bog blueberry (V. uliginosum), velvetleaf blueberry (V. myrtilloides), and bog Labrador tea (Ledum groenlandicum). Willow, birch, mountain alder (Alnus viridis subsp. crispa), white birch, and tamarack border lakes and streams . Black spruce dominates mature and intermediate bog habitats. Alders (Alnus spp.) and willows form the understory in intermediate bog and bog-forest habitats .
Ontario: Star reindeer lichen (Cladonia alpestris), reindeer lichen (C. rangiferina and Cladonia spp.), and spineless reindeer lichen (C. mitis)- rich forests serve as late winter habitat for woodland caribou .
Quebec: Alpine zones >3,300 feet (1000 m) are characterized by ericaceous shrubs, lichens, mosses, and graminoids, while subalpine zones 3,000 to 3,300 feet (900-1000 m) are dominated by open white spruce and balsam fir (Picea balsamea) forest .
Newfoundland: Balsam fir-dominated forests are heavily utilized .
|Boreal forest. Laura Kennedy, U.S. Fish and Wildlife Service, Digital Library System.||Tundra. U.S. Fish and Wildlife Service, Digital Library System.|
Caribou migrate between summer and winter habitats. Spring migration begins as early as mid-February and is typically completed by June [58,69,80]. Early spring thaws allow caribou to migrate to calving grounds early, while late-melting snow packs can delay migrations for a full month . All adult males as well as females that have not successfully bred begin the spring migration in June, often when pregnant females and their yearlings have already reached the calving grounds . A sudden decrease in caribou movements occurs during calving . Winter migrations commence by late September or October. Breeding in migratory herds occurs early into the winter migration . Caribou often follow the same migration routes year after year . For herds summering in northern tundra, forested wintering grounds are up to 800 miles (1,300 km) away. Herds in mountainous areas may move from alpine tundra in summer to forests at lower elevations in winter  instead of undertaking long-distance migrations.
Other seasonal movements are common as well. Midsummer migrations were observed in Northwest Territories herds beginning around mid-August and possibly ending sometime in September . Movements during summer are attributed to harassment by black flies (Simuliidae), bot flies (Oestridae), and mosquitoes (Culicidae) . Caribou move to cool shady forests, windy hilltops, and snow and ice fields to reduce insect attacks. Caribou continue moving and running if they cannot escape insects . Some herds migrate to new areas throughout winter as well [58,80]. In Manitoba, winter movements were most consistent during the coldest periods .
Caribou show strong site fidelity to calving areas [39,103]. Summering ground use is somewhat variable, but the same general areas are often used repeatedly . The locations of wintering sites are highly variable, although some areas are used year after year [29,39,103].
Caribou reach sexual maturity at 16 to 17 months of age [69,89], but yearlings rarely mate [12,103]. Females begin mating at 28 to 41 months of age [12,15,103]. Most males do not breed successfully until they are 4 to 5 years old .
The breeding season ranges from late August to late October or at the beginning of the winter migration [12,103]. Males are polygamous and travel with small bands of females and their calves during the rut [10,69]. Gestation lasts 225 to 235 days [10,12,103]. Parturition takes place in May and June in most herds [1,10,11,12,69,88,90], with a maximum range between late April and early July [10,58]. Females from northern herds typically calve later than those to the south . Females give birth to 1 calf [10,12,15]. Births are highly synchronized, with up to 90% of calves in a herd being born during a 5- to 15-day period [1,12,88]. Post and others  suggested that regardless of predation pressure, calving synchrony and timing are largely influenced by the emergence of edible plants.
Calves are highly vulnerable to predation, which is the most common cause of calf mortality [12,15]. Calf mortality is typically 14% to 77% during the first year [12,67,74,89]. In areas with high densities of gray wolves (Canis lupus) or grizzly bears (Ursus arctos horribilis), calf mortality can exceed 90% . Weather conditions also influence calf production and survival . Winter calf survival in a Peary caribou herd in the Northwest Territories was highest in years with deep, hard snow. However, in the same study, mild winters and less snowfall led to an increase in calf production the following year .
Annual adult mortality is also influenced by predator densities . Natural adult mortality generally ranges 4% to 16% annually [12,74,76,89]. Adults in a small population of woodland caribou in British Columbia suffered unusually high mortality, with an average annual rate of 24% . The maximum lifespan of caribou is around 12 to 16 years [32,69,103].PREFERRED HABITAT:
Caribou distributions within these habitats are influenced by site characteristics and associated vegetation. Caribou frequent peatlands, bogs, muskegs, lake shores, and other wetland and riparian areas [37,61,80,97]. A mosaic of habitats, such as old-growth forest uplands and mature lowland forest adjacent to wetland and riparian areas, are important for feeding and other activities during mid- and late winter in Manitoba and Saskatchewan [80,97]. Habitat heterogeneity is primarily caused by fire . Caribou spend most of their time on level or gently sloping land [81,103]. High-elevation hilltops and ridges are frequently used by caribou throughout the year [81,82,103]. High-elevation habitats include grasslands , alpine habitats characterized by ericaceous shrubs, lichens, mosses, and graminoids, and open subalpine white spruce-balsam fir forest. Woodland caribou in Quebec favored barren habitats with a large component of bare ground in alpine and subalpine zones >2,300 feet (700 m) .
Favored calving grounds for herds near the ocean include gently rising plains and hills >1,200 feet (370 m) in elevation . A calving area in Alaska was characterized by subarctic, mesic, and wet-sedge meadows dominated by Bering Sea sedge (Carex nesophila), purple marshlocks (Potentilla palustris), and field horsetail (Equisetum arvense). Calving habitat in Greenland was characterized by warm, dry, south-facing slopes populated by Bellardi bog sedge (Kobresia myosuroides), weak arctic sedge (C. supina), grayleaf willow, and dwarf birch (B. nana) . Caribou in Newfoundland calved in mature forest and then moved to barrens 2 to 4 days after calving. Extensive scrub habitats interspersed with bogs and barrens were used for calving as well in Newfoundland . Uncharacteristically, females from a nonmigratory herd in Saskatchewan did not use a specific calving location from year to year, but the females did utilize the same general calving area . A herd in Alaska was displaced from its traditional calving area and used a recent burn for calving instead. The traditional area was completely snow covered during the calving period, while the burned area was snow free. Nearby treeless, snow-free unburned areas were generally avoided .
Snow depth and hardness may influence caribou movements and foraging habits more than stand age [78,101]. To find food in winter, caribou favor habitats with reduced snow cover, including western and southern aspects and windy mountaintops [12,106]. Caribou selectively travel and feed in areas with shallow snow, which may explain why stands at least 40 years old are utilized more than younger stands . Caribou dig feeding craters at sites with soft, shallow snow in both burned and unburned sites in Alaska . In early winter, barren ground caribou movements are not yet restricted by snow depth or hardness . Mountain pine beetle (Dendroctonus ponderosae) attacks can affect caribou movements by killing trees and increasing windthrow. Snow depths may increase in areas with reduced canopy cover due to windthrow caused by mountain pine beetle kills. As a result, caribou may abandon once-preferred habitats and utilize areas where predation risks may be higher . Increases in snowfall over several seasons can lead to population declines within caribou herds .
Home range: Caribou home range size is highly variable because some herds are migratory while others are not [69,80,90,103]. Average home range sizes of male and female caribou in Newfoundland were 84.0 kmē and 89.8 kmē, respectively . The range of a woodland caribou herd in Labrador was estimated at 25,000 kmē . The general home range of a woodland caribou herd in Ontario was roughly 160,000 kmē . The primary home range of an Alaskan herd covered roughly 45,000 kmē .
Endangered woodland caribou in the Columbia Mountains: Caribou in the Columbia Mountains primarily inhabit Engelmann spruce-subalpine fir and western red cedar-western hemlock forests >4,000 feet (1,200 m) in elevation . The following table describes the characteristics of habitats utilized by woodland caribou in the Columbia Mountain ecosystem in northern Idaho, northeastern Washington, and southeastern British Columbia.
|Characteristics of woodland caribou habitat in the Columbia Mountains|
|Season||Major habitat characteristics||Tree size||Basal area||Canopy cover||Lichen density||Understory cover||Road density||Other characteristics|
|Early winter||mature to old-growth western redcedar-western hemlock and Engelmann spruce-subalpine fir forests||>20 cm DBH||≥50 mē/ha||>50%||high||...*||...||1,346-1,677 m elevation; 16%-30% slopes; southern aspects, highly productive stands; average windthrown tree density 7.4/ha [6,55,91,102,107,111]|
|Late winter||old-growth Engelmann spruce-subalpine fir and western hemlock forests; ridgetops or upper slopes; also subalpine zones||...||2.3-17.2 mē/ha||26%-50%||high||...||...||>1,526 m elevation; moderate slopes; northern aspects; low tree density; stem densities 741 to 1235/ha [6,102,107]|
|Spring||mature western redcedar-western hemlock-Engelmann spruce forests; forest openings and cutovers adjacent to mature stands; closed canopy forests of various ages||<10 cm, 21-25 cm DBH||<2.3 mē/ha, <45.9 mē/ha||variable||low||...||...||low to midelevation; highly productive stands [6,38,102,111]|
|Calving||mature to old-growth western redcedar-western hemlock and Engelmann spruce-subalpine fir forests; old noncommercial forests; calving females usually secluded||...||≤34.4 mē/ha||low||high||...||lower than other times of the year||1,346 m elevation; low tree density; often snow covered [55,102,111]|
|Summer||western redcedar-western hemlock and Engelmann spruce-subalpine fir forests; partial cuts, pole stands, and old-growth; high meadows adjacent to subalpine forest||...||17.3-34.4 mē/ha||variable||high||>60%||...||average elevation 1,400-1,700 m; northern and eastern aspects, relatively flat terrain at a fine scale; highly productive stands [6,38,102]|
|Fall||mature to old-growth western hemlock; high meadows adjacent to subalpine forest||>20 cm DBH||>45.9 mē/ha||variable||high||high||...||shift to lower elevations following frost [38,102]|
|Rut||...||>25 cm DBH||>45.9 mē/ha||>70%||...||...||1.3 km/kmē||high concentration of snags (>247/ha) |
Johnson and others  identify preferred woodland caribou habitats in the Selkirk Mountains of Idaho, Washington, and British Columbia, and describe potential management conflicts due to human activity and development in the woodland caribou habitats. Prime habitat in the region includes lightly stocked stands with seral and mature Engelmann spruce-subalpine fir and western redcedar-western hemlock stands with <40% crown cover, especially in areas where lakes, bogs, and fens are present. These habitat types provide lichen forage during winter months as well as shrubs and forbs during other times of the year. Within these types, lightly stocked stands on steep southern aspects are vulnerable to fire. Any logging or fire activity within these stands would likely be detrimental to the caribou population .
Engelmann spruce-subalpine fir forest >5,000 feet (1,524 m) with >40% crown cover is another highly preferred habitat in the Selkirk Mountains. Western redcedar-western hemlock stands over 4,500 feet (1,346 m) within the spruce-fir type are used in early winter for feeding, movement corridors, and calving sites. These stands provide cover in late fall, while fallen trees within this habitat provide lichen forage. According to Johnson and others , irregularly shaped clearcuts <40 acres (16 ha) in size and <33% of the original forest size may be removed in a single drainage without serious harm to caribou populations in this habitat .
In the Selkirk Mountains, caribou frequently use sites adjacent to lakes, bogs, and fens for foraging in late summer and fall. Disturbances such as logging, camping, and road traffic near these water sources may be detrimental to caribou using those sites. Limiting the number of roads and utility corridors through preferred habitats would be highly beneficial to caribou in the Selkirk Mountains .
Woodland caribou in British Columbia frequent alpine-rock, lodgepole pine/reindeer lichen-cup lichen, and midelevation mixed spruce-fir-pine (Picea-Abies-Pinus spp.) habitats . Western hemlock habitats are most important for woodland caribou in Idaho and British Columbia during autumn and early winter. However, habitats with western hemlock are largely avoided at other times of the year. Open canopy (10%-25%) is also favored during all seasons in stands without a western hemlock component . Periodically in winter, caribou climb to the high ridges they more typically use in summer. These vertical movements are likely influenced by snow accumulation. Deep snow accumulation at high elevations forces caribou down to mature lowland forests. Caribou return to upper elevations if the snow pack hardens sufficiently. When snow softens in spring, caribou are again forced to lower-elevation forests. They move from low-elevation forests into snow-free alpine habitats in May and June and remain for most of the summer. Woodland caribou in this area inhabit dense, lowland forests that are roughly 4,000 feet (1,200 m) below their summer range during part of each winter. In lowland areas, woodland caribou favor flat, poorly drained areas interspersed with open bogs, meadows and ponds, and mature forests near the open ice of lakes .
Caribou in the Selkirk Mountains return to the same early winter habitats year after year . Early winter habitat in the Selkirk Mountains is characterized by closed-canopy Engelmann spruce-subalpine fir and western hemlock-western redcedar on moderate slopes, with high densities of windthrow and arboreal lichens, at 4,000 to 6,200 feet (1,200-1,900 m) elevation [102,111]. Early winter is considered the most critical time for woodland caribou in the Selkirk Mountains because availability of suitable habitat is limited, rapid snow accumulation covers vascular plants used for forage and makes movement difficult, and arboreal lichen availability is low [91,111]. The accumulated snow hardens in late winter, and caribou are able to walk on top of the snow and more easily reach arboreal lichens in the forest canopy .
Caribou declined after a series of fires that greatly altered the landscape in British Columbia. Fire reduced 60% to70% of this caribou habitat. However, the decline in the caribou population was not noticed for several years following the fires. Caribou avoided burned areas that had been utilized before the fires .COVER REQUIREMENTS:
Lichens are prominent in the caribou diet throughout the year, but reach greatest importance in winter [27,80,96,101]. Lichens commonly eaten are reindeer lichen, star reindeer lichen, spineless reindeer lichen, tree reindeer lichen (Cladonia arbuscula), other reindeer lichens (Cladonia spp.), cup lichens (C. amaurocraea and C. uncialis), cetraria lichen (Flavocetraria nivalis), Iceland-moss (Cetraria islandica), felt lichen (Peltigera canina), and snow lichens (Stereocaulon spp.) [2,12,14,26,80,99,101,108]. Other lichens, including witch's hair lichens (Alectoria jubata, A. sarmentosa, and A. ochroleuca) and brittle lichens (Cornicularia spp.) are locally important food sources when available [2,26]. In British Columbia, horsehair lichens (Bryoria spp.), which are highly valued as forage in the area, are more abundant on subalpine fir and Engelmann spruce than on whitebark pine (Pinus albicaulis), lodgepole pine, or alpine larch (Larix lyallii) .
Lichens are the primary foods of caribou in winter [27,80,96,101]. However, lichens are generally low in nutrients, and caribou often lose weight with a winter diet heavy in lichens [12,33,80]. Caribou may persist on a diet that limits or excludes lichens, since caribou are able to exploit vascular plant resources when available [14,33]. In winter, snow accumulation influences caribou diet [12,92]. By mid-April in Saskatchewan, snow hardening made it difficult for the caribou to forage beneath the snow, so arboreal lichens were the primary available food source followed by terrestrial lichens, bog Labrador tea, and other deciduous shrubs and trees [79,80]. When caribou population densities were high on the Slate Islands in Lake Superior, caribou lightly browsed mountain maple (Acer spicatum), American mountain-ash (Sorbus americana), willows, red-osier dogwood (Cornus sericea), and downy arrowwood (Viburnum rafinesquianum) in winter . Woodland caribou in British Columbia forage on arboreal lichens, subalpine fir, Engelmann spruce, and western hemlock in early winter when show accumulation is rapid. Oregon boxwood (Paxistima myrsinites) and other vascular plants were eaten in early winter when snow accumulation was slow . When the snow forms a hard crust in open habitats, caribou move to forests to feed on arboreal lichens . During periods when snow cover was ≤20 inches (51 cm) deep, woodland caribou in British Columbia fed on grouse whortleberry (Vaccinium scoparium), cup lichens, and horsehair lichens. When snow was ≥24 inches (62 cm) deep, they almost exclusively ate horsehair lichens and possibly small amounts of witch's hair lichen . Overgrazing by caribou has reduced the amount of available forage and habitat on Alaskan islands, while wildfire has reduced lichen availability on the Alaskan mainland .
During northward migration in Saskatchewan in mid-February, barren ground caribou fed in early morning and early evening . Caribou tend to move almost continuously, even when foraging, which reduces the possibility of overgrazing a feeding area . Snow softens by late winter or early spring, making it possible for the caribou to feed on terrestrial lichens and ericaceous plants under the melting snow . Caribou dig craters in the snow to forage for lichens and other vegetation [12,17]. Caribou prefer to crater in soft, shallow snow . Only one caribou feeds in a crater at a time, and they compete for the most preferred craters .PREDATORS:
Gray wolves are the primary predator of adult caribou [76,103]. Fire may lead to an increase in gray wolf populations, especially when other prey species such as moose (Alces alces) increase after fire [15,53].MANAGEMENT CONSIDERATIONS:
A review by Cumming  outlined management guidelines for maintaining caribou populations. Adequate winter habitat includes forest and muskeg fens that provide lichen forage, which is crucial for winter survival. Habitat must provide adequate supplies of other foods and protection against predation. Predator control may be necessary near major calving grounds .
Lichen cover can be maintained or improved by silviculture, whereas fire often has a negative effect. Percent cover of reindeer lichens, cup lichens, and arboreal lichens is typically higher in logged plots than in burned plots [36,116]. Reindeer lichen and cup lichen recovery was greater in a lodgepole pine forest in British Columbia 15 years after a winter harvest than in burned stands in the area. Lichen cover following summer harvest was comparable to burned stands in the area. Partial cutting can maintain arboreal lichen loading over the short term. In the same study, results indicated 80% to 90% of lichen loading remained in Engelmann spruce-subalpine fir forest 2 years after tree harvest . In Ontario, reindeer lichens were observed 2 years after logging .
Caribou have a negative response to clearcut logging. Woodland caribou in Alberta maintained an average distance of 0.75 mile (1.2 km) from recent cut blocks . In Ontario, clearcuts were avoided for 12 years after harvest within traditional caribou winter habitats . Courtois and others  suggested that protecting large mature forest blocks, concentrating tree harvesting activities to large management blocks, and maintaining corridors connecting large forest blocks would benefit caribou. Smith and others  also recommended leaving core caribou habitat intact, limiting the number of fragmented stands created by timber harvesting, and creating large cut blocks to mimic the effects of large-scale fires and minimize edge effects that may promote the expansion of other ungulate species. Small-scale timber harvest promotes an increase in moose populations, which in turn leads to an increase in gray wolf populations. Large-scale timber harvest could benefit caribou by keeping moose and gray wolf populations low . In winter, woodland caribou in British Columbia show a preference for Engelmann spruce-subalpine fir forests with low basal area, moderate timber volume, and moderate slope that are >5,000 feet (1,525 m) elevation. Woodland caribou move through lower elevations, however, to reach the high-elevation habitats. Logging could be possible at lower elevations in this habitat, which would reduce conflicts with caribou . For more detailed information on land management recommendations, see Courtois and others .
Disturbances in caribou habitats have potentially detrimental effects on caribou populations. Caribou avoid railways, roads, and human settlements. Rail and road systems that bisect caribou range may inhibit seasonal movements . A study in Ontario documented an increase in caribou mortality near logging roads via an increase in predation, poaching, and train and traffic accidents. These increases were related to, but not directly caused by, logging activities . Limiting road access and recreation, such as snowmobile use, would benefit caribou . Unexpectedly, an increase in traffic through Denali National Park in Alaska has not caused any noticeable effects on caribou abundance, distribution, or behavior. Individual caribou may become habituated to traffic while others avoid roadways .
The effects of petroleum development on caribou are uncertain. A traditional calving ground near an active Prudhoe Bay oil field shifted approximately 12 miles (20 km) south of the oil field as the herd grew over time. The herd's shift in utilized habitat may have been influenced by petroleum development, but this is uncertain . The use of traditional calving grounds may reduce calf mortality due to reduced predation and higher-quality forage . Shifts away from traditional calving grounds may lead to greater calf mortality and a decline in population size.Cameron and others  advise using caution in when developing oil fields in caribou habitat. After construction of an oil field access road through a caribou calving ground in Prudhoe Bay, Alaska, caribou density declined significantly (P=0.05) within 0.6 mile (1 km) of the road. Relative caribou use of areas adjacent to the road also significantly declined (P<0.02), in apparent conjunction with an increase in surface development. Caribou densities increased significantly (P=0.04) 3 to 4 miles (5-6 km) from the road , indicating a possible shift in habitat utilization. In another study on Prudhoe Bay oil fields, male caribou were observed within 1.2 miles (2 km) of oil field infrastructure during the postcalving season. However, calves were primarily observed 4 to 5 miles (6-8 km) from oil field infrastructure during the postcalving season, although calves were observed closer to infrastructure in some years . These results suggest that oil field development generally has a negative affect on caribou calves and calving females, but more research is needed to make the association clearer.
Starvation following the loss of forage due to fire is a potential threat. During the winter following the large fires in Yellowstone National Park in 1988, thousands of elk (Cervus elaphus) died from starvation . With a long-term loss of forage following fire, major declines in caribou herd size would likely result.HABITAT-RELATED FIRE EFFECTS:
Caribou use burned areas for several reasons. For instance, Miller [79,81] reported that caribou used burned areas as refuges to escape predation. In another study, calving occurred in a recent burn adjacent to a traditional calving area in Alaska . Recent burns are also commonly used during migratory and nonmigratory movements [78,81,96]. In late winter, caribou in Saskatchewan and Manitoba migrated through burned areas in long single lines . Caribou also traverse burned areas between mature forest fragments and meadows [46,101]. Fire in tundra habitats removes woody debris, which facilitates travel . However, burns in forested habitats may inhibit travel between unburned foraging sites. Surface fires can kill black spruce and burn off their roots, making standing snags susceptible to windthrow . Windthrow in recent forest burns may hamper the movements of caribou [61,96,101].
The influence of burns on travel appears to depend on habitat characteristics. Large fires in Quebec during 1954 to 1955 appeared to block winter migration routes to the south, causing caribou to congregate in lichen-rich habitats in northern Quebec. This effect appeared to be short term . Snow accumulation and hardness alters caribou movements. In Alaska, snow hardness was almost significantly greater (P=0.0731) in burned plots than in unburned plots. Fire may encourage earlier snow melt , which could facilitate spring migration (see Timing of Major Life History Events).
Effects of fire on caribou forage: Historically, fire was considered detrimental to caribou due to the destruction of lichen forage caused by fire [52,101]. Now, however, fire is perceived to improve the nutrient cycling and growth of lichens, sedges, shrubs, and forbs [56,96]. Fire reduces lichen availability, but enhances short-term productivity and quality of vascular plants such as sheathed cottonsedge, bog Labrador tea, and mountain cranberry [61,96,97]. The short-term increase in vascular plants enhances summer ranges, but the decrease in lichen availability is detrimental in winter ranges . Late summer regeneration of sheathed cottonsedge following a midsummer tundra fire in Alaska provided food for a caribou herd moving through the burned area in late October . The use of herbaceous vegetation, including sheathed cottonsedge and horsetail (Equisetum spp.), was limited in another study in Alaskan tundra, although availability increased after recent fire .
Lichens are typically consumed by fire, including surface fires, so limited food is available to caribou during early successional stages after fire [61,70]. Frequent fire may delay the regeneration of forests that support lichen growth or convert a burned area into tundra, which may not support lichen growth . Fire affected caribou forage availability but not selection in the Alaskan tundra . Changes in arboreal lichen biomass and availability were affected by high- and low-severity fire and clearcutting in Idaho, Washington, and British Columbia. No arboreal lichens were found on sites that experienced high-severity fire or clearcutting during the previous 40 years. Higher arboreal lichen biomass was found at high-severity burn sites aged 41 to 80 years than on clearcut sites of similar age. Arboreal lichen biomass in low-severity fire sites was higher 41 to 80 years after fire than in low-severity sites 1 to 40 years after fire .
Lichen regeneration following fire depends on many factors including burn patchiness, intensity, severity, extent of the burn, prefire vegetation, seral stage, and climate [61,115]. Reindeer and cup lichens (Cladonia spp.) are virtually absent until a recovering habitat reaches midsuccession [99,101,116]. Lichen regeneration, including reindeer lichens, cup lichens, felt lichens (Peltigera spp.), and arboreal lichens, takes 30 to120 years or more depending on the species [2,36,78,79,80,99,101,108]. Available forage of shrubs and lichens on average is highest in 51- to 120+-year-old stands and lowest in 1- to 10-year-old stands [99,108]. Stands <60 years old may have standing crops of lichens similar to 120-year-old stands . Fire at the landscape level maintains a diverse mosaic of vegetation and successional stages in forested ecosystems, which overall contributes to the availability of lichens .
Fire is necessary in the landscape to maintain lichen forage availability over the long term . Caribou response to fire is influenced by the duration of lichen recovery and availability of alternate feeding sites . In forests >130 years old, terrestrial lichens are replaced by feathermosses, including mountain-fern moss (Hylocomium splendens) and Schreber's moss (Pleurozium schreberi), and vascular plants such as mountain cranberry [24,75,81,97] due to increasing tree density, canopy closure, and litter accumulation [24,75,81]. Fire destroys thick masses of sphagnum mosses (Sphagnum spp.) and feathermosses (Hylocomium spp.) and removes accumulated litter, allowing lichens to regenerate [3,81,93,97,100].
Feltleaf willow is a preferred caribou browse plant and a common associate in Alaska and the Canadian arctic [103,117]. Feltleaf willow is a fire-adapted species that sprouts from the root crown following top-kill by fire [86,115,119]. Feltleaf willow produces abundant, wind-dispersed seed that is important in colonizing burned areas [112,115].
Fire regime: Caribou habitats in taiga generally experience moderate to long fire-return intervals, while tundra habitats rarely burn. Summer fires are rare in northern Canada because of the heterogeneous landscape of wet and dry tundra and rock barrens. Thus, barren ground caribou are typically only affected by fires in their forested winter habitats . The fire season in the Northwest Territories is mid-June to mid-August [41,56]. The fire season in interior Alaska is 1 April to 30 September, with most fires occurring May to July [40,112]. Fires in black spruce/lichen forests in the Northwest Territories and interior Alaska are primarily lightning-caused [41,50,71].
Black spruce-birch forest has the highest fire frequency of any forest type in interior Alaska . Estimated fire-return intervals in the black spruce-birch ecosystem vary from 50 to 200 years [51,115]. Fires occur every 50 to 70 years in black spruce-white spruce/bog birch/reindeer lichen communities in interior Alaska . Heinselman  estimates a fire-return interval of 130 years for open black spruce/reindeer lichen forest and 100 years for closed-canopy black spruce forest. Mean fire-return intervals in lowland black spruce forests on the Kenai Peninsula, Alaska, range from 89 to 195 years [4,72]. Black spruce-birch communities experience high-severity, stand-replacing fires. These communities are highly flammable due to the abundance of ericaceous shrubs, the prevalence of dead, low-hanging branches on the black spruce trees, which are often covered with highly flammable epiphytic lichens, and to the thick moss and lichen mats that cover the forest floor and become highly flammable after periods of low rainfall [70,71,113].
White spruce is also a predominant species in caribou habitat [57,103]. Fire frequency in white spruce forest types is generally 60 to 200 years . Some white spruce forests located in floodplains are >300 years old in Alberta .
Jack pine is an important stand component for caribou in eastern Canadian forests [76,80,99,101]. Estimates of fire-return intervals in jack pine forests are generally <50 years . In northern Ontario, major fire events occur every 5 to 30 years in jack pine forests . The mean fire-return interval for jack pine forests in the Athabasca Plains in northern Saskatchewan and northeastern Alberta is 38 years . Upland ridges and ridge complexes that lack natural fire breaks burn most frequently. Jack pine forests that burn more frequently than every 5 to 10 years become pine barrens . Lichen mats develop within 40 years and support fire in jack pine forests .
Balsam fir habitats are also utilized in eastern Canada [74,82]. Balsam fir is usually rare or absent for the first 30 to 50 years after fire, but establishes thereafter under the canopy of its seral associates [5,35,42].
Engelmann spruce-subalpine fir forests provide prime habitat for endangered woodland caribou in the Columbia Mountains [6,36,55,102]. Engelmann spruce-subalpine fir forests usually develop in cool, moist locations with an average fire-return interval of ≥150 years . Moist, mid- and high-elevation subalpine fir habitat types experience stand-replacing fires at intervals of ≥90 years [7,105].
The following table provides fire regime information that may be relevant to caribou. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".
|Fire regime information on vegetation communities in which caribou may occur. Fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models . These vegetation models were developed by local experts using available literature, local data, and expert opinion as documented in the PDF files linked from the Potential Natural Vegetation Groups listed below.|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Northern Rockies Forested|
|Western larch-lodgepole pine-Douglas-fir||Replacement||33%||200||50||250|
|Lower subalpine lodgepole pine||Replacement||73%||170||50||200|
Replacement=Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Mixed=Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects [45,64].
1. Adams, Layne G.; Dale, Bruce W. 1998. Timing and synchrony of parturition in Alaskan caribou. Journal of Mammalogy. 79(1): 287-294. 
2. Ahti, T. 1959. Studies on the caribou lichen stands of Newfoundland. Annals of the Botanical Society. Vanamo. 30(4): 1-44. 
3. Ahti, T.; Hepburn, T. L. 1967. Preliminary studies on woodland caribou range, especially on lichen stands, in Ontario. Res. Rep. (Wildlife) No. 74. Toronto, ON: Ontario Department of Lands and Forests, Research Branch. 134 p. 
4. Anderson, R. S.; Hallett, D. J.; Berg, E.; Jass, R. B.; Toney, J. L.; de Fontaine, C. S.; DeVolder, A. 2006. Holocene development of boreal forests and fire regimes on the Kenai lowlands of Alaska. The Holocene. 16(6): 791-803. 
5. Apfelbaum, Steven; Haney, Alan. 1981. Bird populations before and after wildfire in a Great Lakes pine forest. The Condor. 83: 347-354. 
6. Apps, Clayton D.; McLellan, Bruce N.; Kinley, Trevor A.; Flaa, John P. 2001. Scale-dependent habitat selection by mountain caribou, Columbia Mountains, British Columbia. Journal of Wildlife Management. 65(1): 65-77. 
7. Arno, Stephen F. 1980. Forest fire history in the Northern Rockies. Journal of Forestry. 78(8): 460-465. 
8. Baker, Robert J.; Bradley, Lisa C.; Bradley, Robert D.; Dragoo, Jerry W.; Engstrom, Mark D.; Hoffmann, Robert S.; Jones, Cheri A.; Reid, Fiona; Rice, Dale W.; Jones, Clyde. 2003. Revised checklist of North American mammals north of Mexico, 2003. Occasional Papers No. 229. Lubbock, TX: Museum of Texas Tech University. 23 p. 
9. Banci, Vivian. 1994. Wolverine. In: Ruggiero, Leonard F.; Aubry, Keith B.; Buskirk, Steven W.; Lyon, L. Jack; Zielinski, William J. The scientific basis for conserving carnivores: American marten, fisher, lynx, and wolverine. Gen. Tech. Rep. RM-254. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 99-127. 
10. Banfield, A. W. F. 1974. The mammals of Canada. Toronto, ON: University of Toronto Press. 438 p. 
11. Banfield, A. W. F.; Tener, J. S. 1958. A preliminary study of the Ungava caribou. Journal of Mammalogy. 39(4): 560-573. 
12. Bergerud, A. T. 1980. Caribou. In: Schmidt, John L.; Gilbert, Douglas L., eds. Big game of North America. Harrisburg, PA: Stackpole Books: 83-101. 
13. Bergerud, Arthur T. 1971. Abundance of forage on the winter range of Newfoundland caribou. The Canadian Field-Naturalist. 85: 39-52. 
14. Bergerud, Arthur T. 1972. Food habits of Newfoundland caribou. Journal of Wildlife Management. 36(3): 913-923. 
15. Bergerud, Arthur T. 1974. Decline of caribou in North America following settlement. Journal of Wildlife Management. 38(4): 757-770. 
16. Brook, Ryan K.; Richardson, Evan S. 2002. Observations of polar bear predatory behaviour toward caribou. Arctic. 55(2): 193-196. 
17. Brown, W. Kent; Theberge, John B. 1990. The effect of extreme snowcover on feeding-site selection by woodland caribou. Journal of Wildlife Management. 54(1): 161-168. 
18. Burson, S. L., III; Belant, J. L.; Fortier, K. A.; Tomkiewicz, W. C., III. 2000. The effect of vehicle traffic on wildlife in Denali National Park. Arctic. 53(2): 146-151. 
19. Cameron, Raymond D.; Reed, Daniel J.; Dau, James R.; Smith, Walter T. 1992. Redistribution of calving caribou in response to oil field development on the Arctic Slope of Alaska. Arctic. 45(4): 338-342. 
20. Carroll, S. B.; Bliss, L. C. 1982. Jack pine - lichen woodland on sandy soils in northern Saskatchewan and northeastern Alberta. Canadian Journal of Botany. 60: 2270-2282. 
21. Cichowski, Deborah; Williston, Patrick. 2005. Mountain pine beetles and emerging issues in the management of woodland caribou in west central British Columbia. In: McCarthy, L.; Valkenburn, P., eds. Proceedings of the 10th North American caribou workshop; 2004 May 4-6; Girdwood, AK. In: Rangifer. Tromso, Norway: Nordic Council for Reindeer Research; Special Issue No. 16: 97-103. 
22. Courtois, Rehaume; Ouellet, Jean-Pierre; Dussault, Claude; Gingras, Andre. 2004. Forest management guidelines for forest-dwelling caribou in Quebec. The Forestry Chronicle. 80(5): 598-607. 
23. Couturier, Serge; Brunelle, Josee; Vandal, Denis; St. Martin, Guy. 1990. Changes in the population dynamics of the George River caribou herd, 1976-87. Arctic. 43(1): 9-20. 
24. Coxson, Darwyn S.; Marsh, Janet. 2001. Lichen chronosequences (postfire and postharvest) in lodgepole pine (Pinus contorta) forests of northern interior British Columbia. Canadian Journal of Botany. 79: 1449-1464. 
25. Coxson, Darwyn; Stevenson, Susan; Campbell, Jocelyn. 2003. Short-term impacts of partial cutting on lichen retention and canopy microclimate in an Engelmann spruce - subalpine fir forest in north-central British Columbia. Canadian Journal of Forest Research. 33: 830-841. 
26. Crete, Michel; Huot, Jean; Gauthier, Line. 1990. Food selection during early lactation by caribou calving on the tundra in Quebec. Arctic. 43(1): 60-65. 
27. Cringan, Alexander Thom. 1957. History, food habits and range requirements of the woodland caribou of continental North America. Transactions, North American Wildlife Conference. 22: 485-501. 
28. Cronin, Matthew A.; Amstrup, Steven C.; Durner, George M.; Noel, Lynn E.; McDonald, Trent L.; Ballard, Warren B. 1998. Caribou distribution during the post-calving period in relation to infrastructure in the Prudhoe Bay oil field, Alaska. Arctic. 51(2): 85-93. 
29. Cumming, H. G. 1992. Woodland caribou: facts for forest managers. Forestry Chronicle. 68(4): 481-491. 
30. Cumming, H. G.; Beange, D. B. 1993. Survival of woodland caribou in commercial forests of northern Ontario. The Forestry Chronicle. 69(5): 579-588. 
31. Curtis, John T. 1959. The vegetation of Wisconsin. Madison, WI: The University of Wisconsin Press. 657 p. 
32. Cuyler, Christine; Ostergaard, Jette Buch. 2005. Fertility in two West Greenland caribou Rangifer tarandus groenlandicus populations during 1996/97: potential for rapid growth. Wildlife Biology. 11(3): 221-227. 
33. Davis, James L.; Franzmann, Albert W. 1979. Fire-moose-caribou interrelationships: a review and assessment. Proceedings, North American Moose Conference Workshop. 15: 80-118. 
34. Davis, James L.; Valkenburg, Patrick. 1983. Calving in recently burned habitat by caribou displaced from their traditional calving area. In: Alaska/Canada north, neighbours in science: proceedings of the 34th Alaska science conference; 1983 September 28-October 1; Whitehorse, YT. [Fairbanks, AK]: American Association for the Advancement of Science, Arctic Division; Ottawa, ON: Department of Indian and Northern Affairs, Northern Program: 19. [Abstract]. In cooperation with: Yukon Historical and Museums Association. 
35. Day, R. J.; Harvey, E. M. 1981. Forest dynamics in boreal mixedwood. In: Whitney, R. D.; McClain, K. M., compilers. Boreal mixedwood: Proceedings of a symposium; 1980 September 16-18; Thunder Bay, ON. COJFRC Symp. Proceedings O-P-9. Sault Ste. Marie, ON: Environment Canada, Canadian Forestry Service, Great Lakes Forestry Research Centre: 29-41. 
36. Detrick, Richard W. T. 1985. Effects of fire and logging on arboreal lichen availability to caribou. Moscow, ID: University of Idaho. 49 p. Thesis. 
37. Dunford, Jesse S.; McLoughlin, Philip D.; Dalerum, Fredrik; Boutin, Stan. 2006. Lichen abundance in the peatlands of northern Alberta: implications for boreal caribou. Ecoscience. 13(4): 469-474. 
38. Edwards, R. Y. 1954. Fire and the decline of a mountain caribou herd. Journal of Wildlife Management. 18(4): 521-526. 
39. Ferguson, S. H.; Elkie, P. C. 2004. Seasonal movement patterns of woodland caribou (Rangifer tarandus caribou). Journal of Zoology. 262(2): 125-134. 
40. Foote, M. Joan. 1983. Classification, description, and dynamics of plant communities after fire in the taiga of interior Alaska. Res. Pap. PNW-307. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 108 p. 
41. Forster, W.; Epp, H.; Lanoville, R. A. 1994. Fire ecology of the caribou range of northwest Canada. In: Proceedings, 12th conference on fire and forest meteorology; 1993 October 26-28; Jekyll Island, GA. Bethesda, MD: Society of American Foresters: 620-627. 
42. Foster, D. R.; King, G. A. 1986. Vegetation pattern and diversity in s.e. Labrador, Canada: Betula papyrifera (birch) forest development in relation to fire history and physiography. Journal of Ecology. 74: 465-483. 
43. Hakala, John B.; Seemel, Robert K.; Richey, Robert A.; Kurtz, John E. 1971. Fire effects and rehabilitation methods--Swanson-Russian Rivers fires. In: Slaughter, C. W.; Barney, Richard J.; Hansen, G. M., eds. Fire in the northern environment--a symposium: Proceedings of a symposium; 1971 April 13-14; Fairbanks, AK. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Range and Experiment Station: 87-99. 
44. Hall, E. Raymond. 1981. Rangifer tarandus: Caribou. In: The mammals of North America. 2nd ed. Vol. 2. New York: John Wiley & Sons: 1103-1106. 
45. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2005. Interagency fire regime condition class guidebook. Version 1.2, [Online]. In: Interagency fire regime condition class website. U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; The Nature Conservancy; Systems for Environmental Management (Producer). Variously paginated [+ appendices]. Available: http://www.frcc.gov/docs/184.108.40.206/Complete_Guidebook_V1.2.pdf [2007, May 23]. 
46. Hanson, William A. 1979. Preliminary results of the Bear Creek fire effects studies. Proposed open file report. Anchorage, AK: U.S. Department of the Interior, Bureau of Land Management, Anchorage District Office. 83 p. 
47. Haskell, Shawn; Ballard, Warren B.; Cronin, Matthew. 2002. Caribou road surveys in the northern oilfields of Alaska: retrospective analysis. In: Wilde, Gene R.; Smith, Loren M., eds. Research highlights--2002: Range, wildlife, and fisheries management. Volume 33. Lubbock, TX: Texas Tech University, College of Agricultural Sciences and Natural Resources: 14. 
48. Heinselman, Miron L. 1973. Fire in the virgin forests of the Boundary Waters Canoe Area, Minnesota. Quaternary Research. 3: 329-382. 
49. Heinselman, Miron L. 1973. Restoring fire to the canoe country. Naturalist. 24: 21-31. 
50. Heinselman, Miron L. 1981. Fire and succession in the conifer forests of northern North America. In: West, Darrell C.; Shugart, Herman H.; Botkin, Daniel B., eds. Forest succession: concepts and applications. New York: Springer-Verlag: 374-405. 
51. Heinselman, Miron L. 1981. Fire intensity and frequency as factors in the distribution and structure of northern ecosystems. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; Lotan, J. E.; Reiners, W. A., technical coordinators. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 7-57. 
52. Holechek, Jerry L. 1981. Brush control impacts on rangeland wildlife. Journal of Soil and Water Conservation. 36(5): 265-269. 
53. Hunter, Malcom L., Jr. 1993. Natural fire regimes as spatial models for managing boreal forests. Biological Conservation. 65(2): 115-120. 
54. Johnson, Chris J.; Alexander, Nancy D.; Wheate, Roger D.; Parker, Katherine L. 2002. Charcterizing woodland caribou habitat in sub-boreal and boreal forests. Forest Ecology and Management. 180: 241-248. 
55. Johnson, Donald R.; Miller, Donald R.; Peek, James M. 1977. Guidelines for human activity within the range of mountain caribou, southern Selkirk Mountains. Misc. Publ. No. 3. Moscow, ID: University of Idaho, Forest, Wildlife and Range Experiment Station. 5 p. 
56. Johnson, E. A.; Rowe, J. S. 1975. Fire in the subarctic wintering ground of the Beverly caribou herd. The American Midland Naturalist. 94(1): 1-14. 
57. Joly, Kyle; Dale, Bruce W.; Collins, William B.; Adams, Layne G. 2003. Winter habitat use by female caribou in relation to wildland fires in interior Alaska. Canadian Journal of Zoology. 81(7): 1192-1201. 
58. Kelsall, John P. 1957. Continued barren-ground caribou studies. Wildlife Management Bulletin Series 1: No. 12. Ottawa: Department of Northern Affairs and National Resources, National Parks Branch, Canadian Wildlife Service. 148 p. 
59. Kinley, Trevor A.; Apps, Clayton D. 2001. Mortality patterns in a subpopulation of endangered mountain caribou. Wildlife Society Bulletin. 29(1): 158-164. 
60. Kinley, Trevor A.; Bergenske, John; Davies, Julie-Anne; Quinn, David. 2003. Characteristics of early-winter caribou, Rangifer tarandus caribou, feeding sites in the southern Purcell Mountains, British Columbia. The Canadian Field-Naturalist. 117(3): 352-359. 
61. Klein, David R. 1982. Fire, lichens, and caribou. Journal of Range Management. 35(3): 390-395. 
62. Klein, David. 1979. Wildfire, lichens and caribou. In: Hoefs, M.; Russell, D., eds. Wildlife and wildfire: Proceedings of workshop; 1979 November 27-28; Whitehorse, YT. Whitehorse, YT: Government of Yukon, Yukon Wildlife Branch: 37-65. 
63. Koch, Peter. 1996. Lodgepole pine commercial forests: an essay comparing the natural cycle of insect kill and subsequent wildfire with management for utilization and wildlife. Gen. Tech. Rep. INT-GTR-342. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 24 p. 
64. LANDFIRE Rapid Assessment. 2005. Reference condition modeling manual (Version 2.1), [Online]. In: LANDFIRE. Cooperative Agreement 04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior (Producers). 72 p. Available: http://www.landfire.gov/downloadfile.php?file=RA_Modeling_Manual_v2_1.pdf [2007, May 24]. 
65. LANDFIRE Rapid Assessment. 2007. Rapid assessment reference condition models. In: LANDFIRE. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S. Geological Survey; The Nature Conservancy (Producers). Available: http://www.landfire.gov/models_EW.php 
66. Larter, Nicholas C.; Nagy, John A. 1997. Peary caribou, muskoxen and Banks Island forage: assessing seasonal diet similarities. Rangifer. 17(1): 9-16. 
67. Larter, Nicholas C.; Nagy, John A. 2000. Calf production and overwinter survival estimates for Peary caribou, Rangifer tarandus pearyi, on Banks Island, Northwest Territories. The Canadian Field-Naturalist. 114(4): 661-670. 
68. Leopold, A. Starker; Darling, F. Fraser. 1953. Effects of land use on moose and caribou in Alaska. Transactions, 18th North American Wildlife Conference. 18: 553-562. 
69. Loughrey, A. G.; Kelsall, J. P. 1970. The ecology and population dynamics of the barren-ground caribou in Canada. In: Proceedings, Helsinki symposium; 1966; Helsinki, Finland. [Paris, France]: UNESCO: 275-280. On file with: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. 
70. Lutz, H. J. 1956. Ecological effects of forest fires in the interior of Alaska. Tech. Bull. No. 1133. Washington, DC: U.S. Department of Agriculture, Forest Service. 121 p. 
71. Lutz, H. J. 1960. Fire as an ecological factor in the boreal forest of Alaska. Journal of Forestry. 58: 454-460. 
72. Lynch, Jason A.; Hollis, Jeremy L.; Hu, Feng Sheng. 2004. Climatic and landscape controls of the boreal forest fire regime: Holocene records from Alaska. Journal of Ecology. 92(3): 477-489. 
73. Lynham, Timothy J.; Stocks, B. J. 1991. The natural fire regime of an unprotected section of the boreal forest in Canada. In: Proceedings, 17th Tall Timbers fire ecology conference; 1989 May 18-21; Tallahassee, FL. Tallahassee, FL: Tall Timbers Research Station: 99-109. 
74. Mahoney, Shane P.; Virgl, John A. 2003. Habitat selection and demography of a nonmigratory woodland caribou population in Newfoundland. Canadian Journal of Zoology. 81(2): 321-334. 
75. Maikawa, E.; Kershaw, K. A. 1976. Studies on lichen-dominated systems. XIX. The postfire recovery sequence of black spruce-lichen woodland in the Abitau Lake region, N.W.T. Canadian Journal of Botany. 54: 2679-2687. 
76. McLoughlin, Philip D.; Dzus, Elston; Wynes, Bob; Boutin, Stan. 2003. Declines in populations of woodland caribou. Journal of Wildlife Management. 67(4): 755-761. 
77. Metsaranta, Juha M.; Mallory, Frank F.; Cross, Dale W. 2003. Vegetation characteristics of forest stands used by woodland caribou and those disturbed by fire or logging in Manitoba. In: Couturier, Serge; van Ginhoven, Quentin, eds. Proceedings of the 9th North American caribou workshop; 2001 April 23-27; Kuujjuaq, QC. In: Rangifer. Special Issue No. 14: 255-266. 
78. Miller, D. R. 1980. Wildfire effects on barren-ground caribou wintering on the taiga of northcentral Canada: a reassessment. In: Reimers, Eigil; Gaare, Eldar; Skjenneberg, Sven, eds. Proceedings of the 2nd international reindeer/caribou symposium; 1979 September 17-21; Roros, Norway. Trondheim, Norway: Direktoratet for vilt og ferskvannsfisk: 84-98. 
79. Miller, Don. 2000. Lichens, wildfire, and caribou on the taiga ecosystem of northcentral Canada. In: Farnell, Rick; Russell, Don; van de Wetering, Debbie. Proceedings of the 8th North American caribou worksop; 1998 April 20-24; Whitehorse, YT. In: Rangifer. Tromso, Norway: Nordic Council for Reindeer Research; Special Issue. No. 12: 197-207. 
80. Miller, Donald R. 1976. Biology of the Kaminuriak population of barren-ground caribou. Part 3. Taiga winter range relationships and diet. Canadian Wildlife Service Rep. Series No. 36. Ottawa, ON: Environment Canada, Wildlife Service. 42 p. 
81. Miller, Donald Ray. 1976. Wildfire and caribou on the taiga ecosystem of northcentral Canada. Moscow, ID: University of Idaho. 129 p. Dissertation. 
82. Mosnier, Arnaud; Ouellet, Jean-Pierre; Sirois, Luc; Fournier, Nelson. 2003. Habitat selection and home-range dynamics of the Gaspe caribou: a hierarchical analysis. Canadian Journal of Zoology. 81(7): 1174-1184. 
83. Mowat, Garth; Heard, Douglas C. 2006. Major components of grizzly bear diet across North America. Canadian Journal of Zoology. 84(3): 473-489. 
84. Nienstaedt, Hans; Zasada, John C. 1990. Picea glauca (Moench) Voss white spruce. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 204-226. 
85. Nybakk, Kai; Kjelvik, Ola; Kvam, Tor. 2000. Golden eagle predation on semidomestic reindeer. Wildlife Society Bulletin. 27(4): 1038-1042. 
86. Parminter, John. 1984. Fire-ecological relationships for the biogeoclimatic zones of the northern portion of the Mackenzie Timber Supply Area. In: Northern Fire Ecology Project: Northern Mackenzie Timber Supply Area. Victoria, BC: Province of British Columbia, Ministry of Forests. 102 p. 
87. Payette, Serge; Boudreau, Stephane; Morneau, Claude; Pitre, Nadia. 2004. Long-term interactions between migratory caribou, wildfires and Nunavik hunters inferred from tree rings. Ambio. 33(8): 482-486. 
88. Post, Eric; Boving, Pernille Sporon; Pedersen, Christian; MacArthur, Megan A. 2003. Synchrony between caribou calving and plant phenology in depredated and non-depredated populations. Canadian Journal of Zoology. 81(10): 1709-1714. 
89. Rettie, W. James; Messier, Francois. 1998. Dynamics of woodland caribou populations at the southern limit of their range in Saskatchewan. Canadian Journal of Zoology. 76(2): 251-259. 
90. Rettie, W. James; Messier, Francois. 2001. Range use and movement rates of woodland caribou in Saskatchewan. Canadian Journal of Zoology. 79(11): 1933-1940. 
91. Rominger, Eric M.; Oldemeyer, John L. 1989. Early-winter habitat of woodland caribou, Selkirk Mountains, British Columbia. Journal of Wildlife Management. 53(1): 238-243. 
92. Rominger, Eric M.; Oldemeyer, John L. 1994. Early-winter diet of woodland caribou in relation to snow accumulation, Selkirk Mountains, British Columbia, Canada. Canadian Journal of Zoology. 68(12): 2691-2694. 
93. Rowe, J. S.; Scotter, G. W. 1973. Fire in the boreal forest. Quaternary Research. 3: 444-464. 
94. Rupp, T. Scott; Olson, Mark; Adams, Layne G.; Dale, Bruce W.; Joly, Kyle; Henkelman, Jonathan; Collins, William B.; Starfield, Anthony M. 2006. Simulating the influences of various fire regimes on caribou winter habitat. Ecological Applications. 16(5): 1730-1743. 
95. Russell, Don. 1979. Fire and the Porcupine caribou winter range. In: Hoefs, M.; Russell, D., eds. Wildlife and wildfire: Proceedings of workshop; 1979 November 27-28; Whitehorse, YT. Whitehorse, YT: Yukon Wildlife Branch: 200-201. 
96. Saperstein, Lisa Beth. 1993. Winter forage selection by barren-ground caribou: effects of fire and snow. Fairbanks, AK: University of Alaska. 79 p. Thesis. 
97. Schaefer, James A.; Pruitt, William O., Jr. 1991. Fire and woodland caribou in southeastern Manitoba. Wildlife Monograph No. 116. Washington, DC: The Wildlife Society, Inc. 39 p. 
98. Scotter, George W. 1967. The winter diet of barren-ground caribou in northern Canada. Canadian Field-Naturalist. 81: 33-39. 
99. Scotter, George W. 1968. Effects of forest fires on the lichen winter ranges of barren-ground caribou in northern Canada. Logan, UT: Utah State University. 127 p. Dissertation. 
100. Scotter, George W. 1971. Wildfires in relation to the habitat of barren-ground caribou in the taiga of northern Canada. In: Proceedings, annual Tall Timbers fire ecology conference; 1970 August 20-21; Fredericton, NB. No. 10. Fredericton, NB: Tall Timbers Research Station: 85-105. 
101. Scotter, George Wilby. 1964. Effects of forest fires on the winter range of barren-ground caribou in northern Saskatchewan. Wildlife Management Bulletin, Series 1, No. 18. Ottawa: Canadian Wildlife Service, National Parks Branch, Department of Northern Affairs and National Resources. 111 p. 
102. Servheen, Gregg; Lyon, L. Jack. 1989. Habitat use by woodland caribou in the Selkirk Mountains. Journal of Wildlife Management. 53(1): 230-237. 
103. Skoog, Ronald Oliver. 1968. Ecology of the caribou (Rangifer tarandus granti) in Alaska. Berkeley, CA: University of California, Berkeley. 699 p. Dissertation. 
104. Smith, Kirby G.; Ficht, E. Janet; Hobson, David; Sorensen, Troy C.; Hervieux, David. 2000. Winter distribution of woodland caribou in relation to clear-cut logging in west-central Alberta. Canadian Journal of Zoology. 78(8): 1433-1440. 
105. Sneck, Kathleen M. Davis. 1977. The fire history Coram Experimental Forest. Missoula, MT: University of Montana. 134 p. Thesis. 
106. Swanson, J. D.; Barker, M. H. W. 1992. Assessment of Alaska reindeer populations and range conditions. Rangifer. 12(1): 22-43. 
107. Terry, Eliot L.; McLellan, Bruce N.; Watts, Glen S. 2000. Winter habitat ecology of mountain caribou in relation to forest management. Journal of Applied Ecology. 37(4): 589-602. 
108. Thomas, D. C.; Barry, S. J.; Alaie, G. 1996. Fire - caribou - winter range relationships in northern Canada. In: Proceedings, 2nd international arctic ungulate conference; August 13-17; Fairbanks, AK. In: Rangifer. 16(2): 57-67. 
109. Thomas, Donald C.; Edmonds, Janet. 1983. Rumen contents and habitat selection of Peary caribou in winter, Canadian Arctic Archipelago. Arctic and Alpine Research. 15(1): 97-105. 
110. U.S. Department of the Interior, Fish and Wildlife Service. 2016. Endangered Species Program, [Online]. Available: http://www.fws.gov/endangered/. 
111. U.S. Fish and Wildlife Service. 1994. Recovery plan: Selkirk Mountain woodland caribou: Rangifer tarandus caribou. Final Revision 2, [Online]. Portland OR: U.S. Fish and Wildlife Service, Pacific Region (Producer). 79 p. Available: http://ecos.fws.gov/docs/recovery_plans/1994/940304.pdf [2007, September 12]. 
112. Viereck, Leslie A. 1973. Wildfire in the taiga of Alaska. Quaternary Research. 3: 465-495. 
113. Viereck, Leslie A. 1975. Forest ecology of the Alaska taiga. In: Proceedings of the circumpolar conference on northern ecology; 1975 September 15-18; Ottawa, ON. Washington, DC: U.S. Department of Agriculture, Forest Service: 1-22. 
114. Viereck, Leslie A.; Foote, Joan; Dyrness, C. T.; Van Cleve, Keith; Kane, Douglas; Seifert, Richard. 1979. Preliminary results of experimental fires in the black spruce type of interior Alaska. Res. Note PNW-332. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 27 p. 
115. Viereck, Leslie A.; Schandelmeier, Linda A. 1980. Effects of fire in Alaska and adjacent Canada--a literature review. BLM-Alaska Tech. Rep. 6; BLM/AK/TR-80/06. Anchorage, AK: U.S. Department of the Interior, Bureau of Land Management, Alaska State Office. 124 p. 
116. Webb, Elizabeth T. 1998. Survival, persistence, and regeneration of the reindeer lichens, Cladina stellaris, C. rangiferina, and C. mitis following clearcut logging and fores fire in northwestern Ontairo. In: Lankester, Murray; Racey, Gerald; Timmermann, Tim, eds. Proceedings of the 7th North American caribou conference; 1996 August 19-21; Thunder Bay, ON. In: Rangifer. Special Issue. No. 10: 41-47. 
117. Wilkinson, P. F.; Shank, C. C.; Penner, D. F. 1976. Muskox-caribou summer range relations on Banks Island, N.W.T. Journal of Wildlife Management. 40(1): 151-162. 
118. Wilson, Don E.; Reeder, DeeAnn M., eds. 2005. Mammal species of the world: a taxonomic and geographic reference. 3rd ed. Baltimore, MD: John Hopkins University Press. 2142 p. 
119. Wolff, Jerry O.; Zasada, John C. 1979. Moose habitat and forest succession on the Tanana River floodplain and Yukon-Tanana upland. In: Proceedings, North American Moose Conference and Workshop No 15; 1979 March 12-16; Soldotna-Kenai, AK. Thuderbay, ON: Lakehead University, School of Forestry: 213-244.