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Williams, T.M. 1995. Beverly calving ground surveys,
June 5-16 1993 and June 2-13 1994. 36 pp.
ABSTRACT
I
estimated the number of caribou on the Beverly herd's calving ground in
June 1993 and 1994 where caribou were counted on aerial photographs
taken along strip transacts flown over the calving grounds.
The 1993 and 1994 surveys respectively resulted in estimates of
52,500 ± 6,100 and 151,000 + 48,700 caribou one year old and
older on the calving grounds.
Based on the proportion of breeding females in each stratum, the
number of breeding females on the calving grounds in 1993 and 1994 was
estimated to have been 37,700 ± 5,700 and 120,000 ± 43,100.
This extrapolates to estimates of total population size of 87,000
± 17,900 and 276,000 ± 106,600.
The 1993 estimate was inconsistent with other data collected
between 1988 and 1993 that indicated consistently high spring
recruitment rates, low wolf sighting rates on the winter range, and
relatively low levels of harvest of Beverly caribou.
There is no evidence that technical problems with the survey were
responsible for the lower estimate in 1993.
The most likely explanation for the low estimate in 1993 is that
not all breeding females aggregated on the calving ground that year.
The peak of calving occurred before 12 June and on 14 June in the
two strata surveyed in 1993, and before 9 June in both strata in 1994.
Overall rates of neonatal mortality in 1993 and 1994 were 11.4%
and 7.2%, respectively.
Wolf predation was the primary cause of neonatal mortality in
both June 1993 and 1994, causing 70% (n=33) and 61% (n=28) of
mortalities, respectively.
Results obtained in 1994 are consistent with other data, and
indicate that the Beverly herd has remained stable in size since 1984.
At current levels the herd is above the 150,000 level identified
by the Beverly and Qamanirjuaq Caribou Management Board as the level
below which emergency management action will be considered. |
