Peary caribou and barren-ground caribou COSEWIC assessment and status report: chapter 13

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Summary of Status Report

Subspecies and distribution

Peary caribou are distinct from barren-ground caribou and no intermediate forms are recognizable at the subspecies level. Nevertheless, phenotypic and genotypic variations have been documented among the populations discussed in this report and the conservation of this diversity should be a primary goal of conservation and management. Peary caribou occupy the Queen Elizabeth Islands, Banks Island, the northwest corner of Victoria Island, Prince of Wales Island, Somerset Island, numerous smaller islands, and the Boothia Peninsula (and seasonally or irregularly on the mainland south to the Hayes River).

Caribou of the Dolphin and Union herd occupy the remainder of Victoria Island and adjacent parts of the mainland and are phenotypically and genetically distinct from both barren-ground caribou and Peary caribou.

Current population status

The current status of the main Peary caribou populations, not including calves, is shown in Figure 18. Data are from Gunn and Dragon (2002) for the Melville Island complex; Ferguson et al. (2001) and M. Ferguson, Nunavut Wildlife Service, pers. comm., Nov. 19, 2002) for Bathurst Island; Peary Caribou Recovery Team 2001 for the eastern Queen Elizabeth Islands; Nagy (unpubl. data) for Banks Island and northwestern Victoria Island; and Gunn and Dragon (1998) for the Prince of Wales-Somerset Island and Boothia populations. (The Prince of Wales-Somerset population has been inflated to 60±20 as noted above and the NW Victoria and Boothia populations bars have been reduced by half to exclude the Dolphin and Union and barren-ground caribou, respectively.)

The best current estimate for total (including calves) Peary caribou is 7890 and range of population estimates for total caribou, using errors measurements (either Standard Error or 95% CI) of the original surveys with modifications as described in the Population Sizes and Trends section is 5971 to 9146.

Recent population trends

To determine recent population trends, the most recent estimates have been compared with 1980 estimates, representing a nominal 3 generations of caribou (7 years/generation=21 years). The most recent populations have also been compared with the first reported estimate to give a measure of change from historic levels. The data used in these calculations are given in Appendix 1, Tables 5 to 10.

All 4 Peary caribou populations have suffered serious declines. Where multiple-year time series are available, some of the declines have been more or less gradual, in the range of -5% to -22%, except for the Bathurst Island complex local population. It experienced the sharpest and deepest declines twice (1973-1974 and again in 1994-1997). Multi-year increases have also been documented in the Bathurst Island complex (1974-1994), the Boothia Peninsula (1975-1995), the Banks Island–northwestern Victoria Island population (1998-2001) and the Dolphin and Union herd (1980-1998). The Dolphin and Union herd has apparently increased from 3424 in 1980 to about 27 800 in 1997, but there is doubt about the 1980 estimate; the actual population may have been considerably higher. Increases also occurred previous to scientific surveys in the Banks Island-northwestern Victoria Island population and in the Prince of Wales-Somerset and Boothia Peninsula population, according to Aboriginal traditional knowledge. The eastern Queen Elizabeth Island population has also increased according to Inuit from Resolute Bay and Grise Fiord, but was only surveyed in 1961.

Peary caribou and Dolphin and Union caribou have continued their decline from historic levels (Table 3). The current population estimates in the eastern Queen Elizabeth Islands and Boothia Peninsula have a high degree of uncertainty.

Data are from Appendix 1, Tables 5 to 10.

Threats

Peary and Dolphin and Union caribou are threatened (Table 4) by:

• Recurring severe winters can decimate populations within 1-3 years. Peary caribou have the ability to reoccupy previously abandoned range through inter-island emigrations.
• Industrial activities including seismic exploration and shipping have the potential to interfere with Peary caribou use of habitat and inter-island migration and Dolphin and Union caribou island-mainland migration.
• Climate change may have negative effects including increased snowfall and greater variability in snow depth and hardness. The latter is the most serious threat to Peary caribou and could eliminate the subspecies.
• Some populations may be below an “effective population size” in terms of genetic diversity caused by genetic bottlenecks following population crashes.

Conservation and recovery

• Following population declines, recovery of Peary caribou can be as high as 19% per year per year for short periods, but long term (>10 years) rates of increase may be around 13% if no weather-related die-off occur. (e.g., The Dolphin and Union herd has increased at 24% per year for short periods (e.g., 1994–1997).
• Because of the small populations and subspecific genetic and phenotypic differences among them (that may also represent unique adaptations to specific environments), conservation of the full range of genetic diversity among these populations is paramount.

Other status assessments

The World Conservation Union assessed Peary caribou as EN (endangered) in 1996 based on (1) reduction in population by 50% over the previous 10 years and (2) population <2500 and an estimated continuing decline of 20% within 5 years.