Peary caribou and barren-ground caribou COSEWIC assessment and status report: chapter 7

Habitat

Habitat requirements

Miller (1991) described Peary caribou habitat and it is well enough known not to need extensive review. The climate of the Queen Elizabeth Islands was summarized by Miller (1991): weather is variable and severe with short, cool summers and long, cold winters. Total annual precipitation normally averages < 100 mm, defining much of the range as polar desert. Air temperatures average below -17.7°C from December to March and mean daily temperatures generally do not rise above 0°C until after 1 June on the extreme south of the region or 15 June on the north of the region. Snow cover can persist from mid-August to the following July in the most severe years. Across the Arctic islands, the climate is strongly regionalized with east-west and north-south gradients in precipitation and temperatures due to the influence of Pacific air masses in the west and Atlantic air masses in the east (Maxwell 1981).

The following habitat notes are from Miller (1991). Icefields, bare ground and rock limit the area of suitable forage for Peary caribou to a small percentage of the total area. Peary caribou use poorly to moderately vegetated dry to moist habitats. Forage of high digestibility is selected when available but when not they eat more low digestibility forages. Summer foraging areas are on mesic habitats with sedges (Carex spp.), willow (Salix arctica), grasses and forbs, especially purple saxifrage Saxifraga oppositifolia). In winter, caribou use more exposed sites with shallower snow cover. On Somerset Island, winter range is mainly broken rock outcrops where snow depth is variable but usually soft and less often crusted. Winter foraging sites are xeric and vegetated with dryas (Dryas integrifolia), purple saxifrage, arctic willow, sedges and lichens.

Caribou can travel 3-4 km per hour while actively foraging (Miller et al. 1982). Under ideal conditions when the snow is soft and relatively shallow, the caribou forage by simply pushing the snow off the vegetation with their noses. When the snow cover is denser but still above a ‘threshold hardness, they dig small individually scattered craters, unlike the large cratered areas often used by muskoxen and mainland barren-ground caribou. Once the snow cover passes a threshold hardness and greater density, the caribou seek forage at snow-free sites or at sites with only shallow fresh snow cover. Caribou will also forage by breaking blocks of hard-packed snow off edges of windblown areas to get to the vegetation.

On Banks Island, caribou often feed in winter by cratering in the snow of upland habitats (upland barrens, hummock tundra, and stony barrens) where it is softer and shallower than in wet meadows, and snow depth and hardness can be used to determine winter severity (Larter and Nagy 2000b).

Schaefer and Messier (1994) described the spatial structure of plant communities in southeast Victoria Island: (1) graminoid-dominated wet meadows (Carex aquatilis-C. Atrofusca-Eriophorum angustifolium), (2) wetter willow-sedge meadows (Salix lanata-Kobresia spp.-Arctagrostis latifolia), (3) mesic-hydric meltwater slopes (Eroiphorum angustifolium and Cassiope tetragona), (4) sparsely vegetated uplands (Poa spp.-Carex rupestris-Saxifraga tricuspidata-Oxytropis maydelliana), (5) raised beaches with little vegetation, (6) mesic-xeric areas of Carex rupestris-C. misandra-Kobresia spp.-Dryas spp.), (7) xeric, highly exposed communities of Carex ruprestris-Cetraria-Saxifraga oppositifolia, and (8) mesic between-polygon communities of Arctagrostis latifolia--Dryas spp.-Oxytropis maydelliana).

Banks Island is the only Peary caribou habitat with extensive, well-vegetated rolling hills that fall mostly within the “wet tundra class” of the satellite image-generated North American Land Cover database (Gunn and Dragon 1998). The 4 principal Banks Island caribou habitats are (Kevan 1974, Wilkinson et al. 1976, Ferguson 1991, Larter and Nagy 2000b):

  1. Wet sedge meadows are generally level hydric and hydric lowlands characterized by water sedge (Carex aquatilis), cotton sedge (Eriophorum scheuchzeri), and tundra grass (Dupontia fisheri).
  2. Upland barrens are well drained sites found on the upper and middle parts of slopes. Vegetation is dominated by mountain avens (Dryas integrifolia) and arctic willow (Salix arctica).
  3. Hummock tundra is found on moderately steep slopes and is characterized by individual hummocks which are vegetated primarily by dwarf shrubs including mountain avens, arctic willow and arctic heather (Cassiope tetragona).
  4. Stony barrens have a coarse gravelly substrate and are sparsely vegetated. This habitat is found on wind blown areas, ridges and gravel and sand bars.

Calving, post-calving, and rutting areas are likely critical habitats because caribou are vulnerable as they congregate in those areas. This is a particularly important concern as the use of those areas is at times when uninterrupted foraging is important to the annual cycle of physical condition and calf growth. Cows are faithful to calving areas (Gunn and Miller 1986, Heard and Stenhouse 1992, both cited in Gunn 1993) although calving is at a lower density and more dispersed than the high densities usually described for barren-ground caribou (Gunn and Fournier 2000, Nishi and Buckland 2000). Calving site fidelity is balanced, however, by occasional range shifts within a population’s traditional territories, which allows forage to recover in 1 area while caribou use the available forage in another part of their territory. Also, caribou may shift calving locations because of snow and ice conditions in 1 calving area while in search for better conditions in another. Banks Island caribou calve on the northwest and northeast tips of the island and in the mid-east coastal area across Prince of Wales Strait from Victoria Island (Larter and Nagy 2000a). Likewise, the Minto Inlet herd on Victoria Island calves just across Prince of Wales Strait from Banks Island, while the Dolphin and Union population calves south of Prince Albert Sound (Gunn 1993). Aboriginal traditional knowledge suggests that the Dolphin and Union herd also calves, or used to calve, north of Prince Albert Sound (Gunn 1993).

Calving areas of the Prince of Wales-Somerset and Boothia populations have included the Wrottesley Inlet area on northwestern Boothia Peninsula, the Aston Bay area on the northwest coast of Somerset Island, the southwestern Arrow Smith Plains, the northeastern coastal area from Young Bay to Inner Browne Bay, the northwest coast and the Mount Clarendon ‘peninsula-like’ area of northwestern Prince of Wales Island and western Russell Island (Fischer and Duncan 1976, Miller and Gunn 1978, 1980, Miller and Kiliaan 1981, Miller et al. 1982). Many caribou from Somerset Island used to cross to Prince of Wales Island for calving (Gunn and Dragon 1998). 

The variability of weather parameters such as mean daily temperatures and snowfall contributes to the severity of the climate (Miller and Gunn 2003a). This is because Peary caribou are at the edge of the range for herbivores as the High Arctic is close to the climatic limits for plant growth. The plant growing season is brief and relatively fixed in duration but the timing of the onset of plant growth is annually variable (Svoboda 1977). For example, Svoboda (1977) reported only 45 to 80 days separated the time between snowmelt to mean temperature below freezing in 1970, 1971 and 1972 at Devon Island’s Truelove Lowlands. At Resolute on Cornwallis Island, the number of days with temperatures above 0º during the same 3 years averaged 61±13.5 SD days and ranged from 46 to 72 days (Miller and Gunn 2003a). Therefore, in some years, the renewal of plant growth can be delayed at least 2 to 3 weeks in June when lactating cows need high quality forage from new plant growth.

The absolute availability of forage (plant growth) is driven by climate variability, and the relative availability of forage during the 10-month season of snow and freezing conditions is also governed by climate variability (the timing and type of snowfall etc.). Thus, Peary caribou live in a ‘non-equilibrium grazing system’ where sporadic, unpredictable abiotic variables--i.e., snow and ice--usually govern the fate of the caribou over time (e.g., Caughley and Gunn 1993, Behinke 2000, Miller and Gunn 2003). Under such environmental conditions, the broad distribution of Peary caribou across the various climate regions has enhanced the probability of persistence.

Trends in habitat

Miller (1991) noted that in temperate region ungulate management, winter range is regarded as controlling the upper limits of population, but in the Arctic, summer range may be critical because of the short growing season available for caribou to build up their fat reserves. He found no evidence that either winter or summer habitats were limiting factors in terms of absolute forage availability. Peary caribou researchers (e.g. Gunn 1998b, Miller 1998, Larter and Nagy 2000b, Ferguson et al. 2001, Gunn and Dragon 2002, Miller and Gunn 2003b) are careful to distinguish between absolute forage availability and relative or seasonal availability when limited by winter snow and ice.

Although communities are likely to increase in size and some oil and gas and mining development is possible, effects on habitat are likely localized and the overall trend in habitat will be unaffected. Atmospheric transport brings pollutants to the Arctic, but implications for trends in habitat are unknown (Arctic Monitoring and Assessment Programme 1997). In caribou from the Kent Peninsula sampled in 1993, Belkin (pers. comm. to Gunn and Nishi 1998) found relatively low concentrations of organochlorine, heavy metal and radionuclide contaminants.

Protection/ownership

Most Peary caribou range is in Nunavut, but Banks Island, the northwest quarter of Victoria Island and the major part of the Melville complex on the southwestern Queen Elizabeth Islands and virtually all of the Prime Minister Group on northwestern Queen Elizabeth Islands are in the Northwest Territories. Most land in the Northwest Territories and Nunavut is federal Crown land.

A new National Park, Aulavik (12 000 km²), has been established on Banks Island (Quttinirpaaq National Park, 39 500 km², on Ellesmere Island was established previously). Polar Bear Pass National Wildlife Area, with 2461 km² of land area, is on central Bathurst Island. Banks Island also has 2 migratory bird sanctuaries. A national park is also being planned for northern Bathurst Island. Although these designations provide protection for habitat, Inuit and Inuvialuit retain their rights, as defined by land claims settlements, to hunt Peary caribou for subsistence purposes in all protected areas.

Management authorities

Wildlife in the Peary caribou range is co-managed by governments and Inuvialuit pursuant to the Inuvialuit Final Agreement and by governments and Inuit pursuant to the Nunavut Land Claims Agreement. While the terms of these agreements differ, in general they recognize the Aboriginal rights of Inuit and Inuvialuit to manage the harvest of wildlife, subject only to the need for conservation and public safety. The circumstances in which either the territorial or federal governments can intervene in these rights are carefully circumscribed by the terms of the agreements. The primary management authorities are two wildlife co-management boards: the Wildlife Management Advisory Council (WMAC) for the Inuvialuit Settlement Region in the Northwest Territories and the Nunavut Wildlife Management Board (NWMB) for Nunavut. Although their mandates differ somewhat, both organizations bring together aboriginal and government representatives.

In the Northwest Territories, the Inuvialuit Game Council represents hunters’ and trappers’ committees from 6 Arctic communities and appoints Inuvialuit members to the WMAC. The Department of Resources, Wildlife and Economic Development (Government of the Northwest Territories) and the Canadian Wildlife Service (Government of Canada) participate on the WMAC and undertake research. In Nunavut, the Nunavut Department of Sustainable Development and the Canadian Wildlife Service both appoint members to sit on the NWMB, along with Inuit appointed by their regional organizations. NWMB membership also includes other federal departments and Nunavut Tunngavik Incorporated. As an institution of public government, all NWMB members represent the public interest and not necessarily the interests or opinions of their appointing bodies. These boards are supported by local hunters’ and trappers’ associations and other community committees:

  • Sachs Harbour Hunters and Trappers Committee
  • Olokhaktomiuk Hunters and Trappers Committee (Holman Island)
  • Kugluktuk Angonaitit Association
  • Burnside Hunters and Trappers Association, Bathurst Inlet
  • Omingmaktok Hunters and Trappers Organization, Bay Chimo
  • Ekaluktutiak Hunters and Trappers Organization, Cambridge Bay
  • SpenceBay Hunters and Trappers Association, Taloyoak
  • Gjoa Haven Hunters and Trappers Organization
  • Kurtairojuark Hunters and Trappers Organization, Kugaaruk
  • Kitikmeot Hunters and Trappers Association
  • Kitikmeot Inuit Association
  • Qikiqtaani Inuit Association
  • Resolute Bay Hunters and Trappers Organization
  • Grise Fiord Hunters and Trappers Organisation
  • Qikiqtaaluk Wildlife Board, Baffin Region

The relevant government departments and the wildlife management boards cooperate across interjurisdictional boundaries according to the provisions of the land claims.

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