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Anne Gunn and Judy Dragon. 2000. Peary Caribou and Muskox Abundance and Distribution on the Western
Queen Elizabeth Islands, Northwest Territories and Nunavut June-July 1997.
87 pp.
ABSTRACT
Peary
caribou (Rangifer tarandus pearyi)
have been recognised nationally as “Endangered” since 1991.
Both Peary caribou and muskoxen (Ovibos
moschatus) experienced major winter/spring die-offs during 1994/95 and
1995/96 on, at least, the western Queen Elizabeth Islands of Bathurst and
its satellite islands of Vanier, Cameron, Alexander, Massey and Marc.
Those known losses and a lack of recent information for other
western Queen Elizabeth Islands led us to carry out an aerial survey to
estimate Peary caribou and muskox abundance and relative distributions in
summer 1997.
We used a standard, systematic, stratified, fixed-strip width (0.5
km either side of the transect line) aerial survey design.
A fixed-over-winged, single engine Helio-courier was the survey
aircraft and flew at ca. 100 m above ground level and at an airspeed of ca.
160 km ·
h-1.
We saw live caribou on only 6 of the 15 islands surveyed and
caribou carcasses on 12 islands.
We saw only 2 calves among 378 caribou counted.
We estimated 1086 ±
131 SE 1+ yr-old Peary caribou within the 87 992 km2 survey
area:
Melville Island, 787 ±
97 SE (1.9 caribou ·
100 km-2) at 18% aerial coverage; Bathurst Island,
74 ±
25 SE (0.5 caribou ·
100 km-2 at 20% coverage; and Prince Patrick Island, 84 ±
34 SE (0.5 caribou ·
100 km-2) at 16% coverage.
We estimated from carcass counts that 831 ±
86 SE Peary caribou had died during winter/spring 1996/97 on the western
Queen Elizabeth Islands.
The number of carcasses estimated for Bathurst and its satellite
islands (408 ±
53 SE) indicates that most of the Peary caribou alive there in summer 1996
died during the third of three exceptionally severe winter/spring periods
with twice the long-term average snowfall.
The 1997 estimate is the lowest recorded for the western Queen
Elizabeth Islands since the first aerial survey estimate in 1961 (when the
mean estimate equalled 19 456 1+ yr-old Peary caribou) and represents an
overall 94% decline in the mean estimated number over 36 years.
The available evidence is that the 43% decline in the number of
Peary caribou across the western Queen Elizabeth Islands during
winter/spring 1996/97 was caused by caribou dying during the third
consecutive unusually severe winter and spring on Bathurst and its
satellite islands and a similarly severe winter/spring on the other
western islands in at least 1996/97.
We saw 1066 1+ yr-old muskoxen on only 4 of the 15 islands
surveyed, 2 calves and 57 muskox
carcasses on 3 of those 4 islands.
We estimated 2515 ± 276 SE 1+ yr-old muskoxen within the entire
survey area with an overall mean density of only 2.9 muskoxen ·
100 km-2.
We suggest that only exceptionally extreme environmental episodes
could cause such a degree of spatially and temporally correlated deaths in
two species with markedly different seasonal and annual site-use patterns
on the same ranges. |
