Peary caribou and barren-ground caribou COSEWIC assessment and status report: chapter 2

Executive Summary

Peary Caribou
Rangifer Tarandus Pearyi
and
Barren-ground Caribou
Rangifer Tarandus Groenlandicus
(Dolphin and Union Population)

Species information

English name:

Peary caribou

French name:

Caribou de Peary

Inuinnaqtun name:

Ualiniup Tuktui (plural). Tuktu (singular) preceded by a place name, such as “kingailik tuktu” meaning “Prince of Wales Island caribou”

Latin name:

Rangifer tarandus pearyi (Allen 1902)

Peary caribou occur as at least 4 distinct populations: (1) Queen Elizabeth Islands; (2) Banks Island and northwestern Victoria Island; (3) Prince of Wales Island and Somerset Island, and (4) Boothia Peninsula.

The “Dolphin and Union” barren-ground caribou are included in this report because they were included in the previous COSEWIC assessment. They summer on Victoria Island and cross Dolphin and Union Strait to winter on the mainland. This herd is genetically distinct from both Peary caribou and other barren-ground caribou (Rangifer tarandus groenlandicus) and for the purpose of this report is considered separatelyFootnote1.

A taxonomic revision of caribou on Canadian Arctic islands is required. In particular the description of Dolphin and Union caribou as R. t. groenlandicus-pearyi (Manning 1960) needs revision to reflect their genetic and phenotypic distinctiveness.

Peary and Dolphin and Union caribou are integral components of Inuit and Inuvialuit culture, economy, and spirit world.

Distribution

The normal range of Peary caribou is entirely within the Arctic Archipelago, except for a population on the Boothia Peninsula. Some individuals from the Boothia Peninsula winter as far south as the Hayes River. A few Peary caribou have occurred sporadically to the west on the coastal mainland near Cape Bathurst and at Old Crow, Yukon during environmentally stressful years on Banks and Victoria islands. Peary caribou do not occur on Baffin Island or on the islands in the Foxe Basin and Hudson Bay, where barren-ground caribou (R. t. groenlandicus) occur.

Habitat

Peary caribou and the caribou of the Dolphin and Union herd live exclusively in arctic tundra in environments that range from relatively flat and featureless in the south and west to mountainous in the north and east. When winter snow and ice conditions are extreme, survival depends on finding snow-free or shallow snow-covered ridges and other topographical exposures where they feed on a variety of shrubs, gramminoids, and forbs in mesic to xeric sites. 

Characteristically, Peary caribou migrate seasonally between islands. Infrequently, Peary caribou make environmentally forced movements to other islands and to the mainland. The caribou of the Dolphin and Union herd seasonally migrate across the sea-ice to winter on the mainland and to return to Victoria Island for calving, summer, and the rut. Peary caribou live in a ‘non-equilibrium grazing system’ where sporadic, unpredictable, abiotic variables such as snow and ice usually govern their fate.

Except for those on the Boothia Peninsula, Peary caribou live on islands and inter-island movements are critical to their survival. Inter-island movements within traditional ranges are common and can be characterized as seasonal or periodic range shifts to optimize use of available habitat. Inter-island movements outside of traditional ranges are widely thought to occur on an infrequent basis, but have not been documented.

Peary caribou habitat is stable, large, (>800 000 km2) and relatively unchanged by human activities. Trends in habitat quality have not been well documented. The productivity of the land is low and pockets of higher quality forage are thinly scattered over large areas. Some population declines have been related to sporadic winter snow and icing events that caused the forage to become temporarily unavailable. Other declines have been more gradual and prolonged; in these, winter severity was a factor in some cases, as was hunting.

All populations are under the primary management of wildlife co-management boards established pursuant to the Inuvialuit Final Agreement in the west and the Nunavut Land Claims Agreement in the east.

Biology

Peary caribou face a brief pulse of high quality nutrition during the plant growth season and about 10 months when most plant nutrients are stored in below-ground plant structures. Some dwarf shrubs have evergreen leaves and some grasses and sedges also have over-winter green leaves. Peary caribou nutrition is closely tied to plant phenology, especially green-up in spring and flowering in summer. All seasons are critical:  spring for gestation and to replace energy stores lost during the winter, summer for lactation and growth, summer and fall to build up energy reserves for the early winter rut, and winter to find enough food to survive the harsh arctic environment.

Peary caribou males typically reach breeding age at 4 years, and females at 3 years (rarely 2 years); both sexes are reproductively capable up to at least 13 years and may live up to at least 15 years. About 80% of 3+ yr-old females produce calves in good years. In severe winters, yearling recruitment can drop to 0. Pregnancy rates vary from nearly 0% to 100% and are associated with physical condition of adult females. Except during exceptionally severe winters, winter calf survival ranges from about 20% to 90% and is often greater than 50%.

Peary caribou populations can increase at annual rates of up to about 19% for short periods of a few years. Over periods of a decade or more, population increases of no more than about 13% per year have been observed. 

Peary caribou are found in small groups relative to barren-ground caribou which likely reflects foraging strategies, relatively low caribou densities, and the absence of intense insect harassment. Relative to other caribou, lichens form lower proportions of Peary caribou diets, and mosses higher. Peary caribou have larger rumens relative to other caribou, which may be an adaptation to lower-quality forage. They also have other adaptations to the High Arctic such as a long, densely-haired winter pelage, furry muzzle, short face and short, broad hooves. In winter, once snow/ice pack characteristics prevent or make cratering energy-inefficient, they forage on windswept ridges and hilltops, and in boulder fields where snow is soft and not crusted by wind. During widespread icing conditions, caribou leave iced-over range and seek forage on ice-free and snow-free or shallow snow-covered sites on south-facing slopes, ridges and prominences, which also are where spring green-up occurs earliest. After green-up, Peary caribou feed selectively, favouring flowers that are high in energy and protein.

If Peary caribou went extinct, it is unlikely that other caribou could fill the ecological niche that they now occupy. This is likely also true of the Dolphin and Union herd.

Population sizes and trends

Tracking population trends is hindered by the irregular timing of surveys to estimate numbers (except for the populations on Banks and Bathurst islands). The eastern Queen Elizabeth Islands were covered by a virtually range-wide aerial survey in 1961 and have not been widely surveyed since then. Peary caribou populations have continued to declines since the 1991 assessment report (Miller 1991), which used data up to 1987. The 1991 assessment report identified declines of 86% (1961-1987) for the 2 local populations in the western Queen Elizabeth Islands, a 50% decline on Banks Island and trends were either stable or not discernable for the other metapopulations. Over the last 3 generations (i.e., since about 1980), Peary caribou have declined overall by about 72%¾but 84% in the last 4 decades. Since 1980, the Peary caribou of the Queen Elizabeth Islands have declined by about 37% (despite increasing at 13% per year from 1974 to 1994 within the Bathurst Island complex), the Banks Island-northwestern Victoria Island population by about 72%, and the Prince of Wales-Somerset population by about 99%. The Boothia population has increased by about 10%. The best current estimate for total (including calves) Peary caribou is 7890 and the range of population estimates is 5971 to 9146.

The Dolphin and Union population, historically estimated at about 100 000, was reduced to a handful by about 1924, and has since recovered to about 25% of its former abundance.

Limiting factors and threats

Factors known to have contributed to caribou declines include:  (1) irregular winter events with heavy and persistent snow accumulation, particularly in association with freezing rain or unusually warm periods resulting in deep, crusted snow or a glaze of ice covering the forage; and (2) unsustainable hunting.

Interactions with muskoxen (Ovibos moschatus), possibly involving predator-prey interactions or competition for space or forage, have been suggested as contributing to Peary caribou population declines, but have not been demonstrated as a cause, despite the relatively high mean density of muskoxen in association with caribou. Although there is no evidence for wolves having seriously depressed these caribou populations, their potential impact is much greater now that the caribou populations are so small.

Industrial activities have the potential to threaten both Peary and Dolphin and Union caribou by interrupting migration or causing excessive disturbance during critical life stages such as calving, rutting or winter and spring-summer foraging. Population-level impacts have not, however, been demonstrated.

Genetic diversity and numbers are so low in at least 1 population (Prince of Wales-Somerset) that its ability to adapt to environmental challenges may be seriously compromised and its susceptibility to inbreeding depressions is a concern. The same may also be true of the Peary caribou of the western Queen Elizabeth Islands.

Climate change is the most serious threat. If it were to increase the frequency and severity of winter icing events, Peary caribou would probably go extinct or experience local extirpations. In such a situation, populations would be unable to sustain any large annual harvests.

Special significance of the subspecies

Peary and Dolphin and Union caribou are endemic to Canada, they are the only cervid in the Arctic Archipelago, are uniquely adapted to the polar desert environment, and play a key role in the culture and economy of Inuit and Inuvialuit.

Existing protection or other status designations

Peary caribou are protected by the land claim agreements mentioned above that recognize and specify Aboriginal rights to harvest wildlife, subject to conservation and public safety, and which provide for the establishment of wildlife management boards. Local management authorities, such as hunters’ and trappers’ organizations and regional wildlife organizations, have the authority to restrict or prohibit hunting by their members. The authority of the wildlife management boards is subject to the ultimate responsibility of government.  There are no lands where hunting is prohibited by statute.

Industrial operations are normally required to avoid harassment or other disturbance to caribou under the terms of their territorial and/or federal operating permits or licences of occupation.

COSEWIC designated Peary caribou of the Queen Elizabeth Islands (the “High Arctic”) population and Banks Island as endangered, and the Prince of Wales-Somerset, Boothia and Dolphin and Union (collectively, “Low Arctic”) populations as threatened in 1991. The World Conservation Union assessed Peary caribou as endangered in 1996.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed  under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2004)

Species
Any indigenous species, subspecies, variety, or geographically or genetically distinct population of wild fauna and flora.

Extinct (X)
A species that no longer exists.

Extirpated (XT)
A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A species facing imminent extirpation or extinction.

Threatened (T)
A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnotea
A species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)Footnoteb
A species that has been evaluated and found to be not at risk.

Data Deficient (DD)Footnotec
A species for which there is insufficient scientific information to support status designation.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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