Subject: Endangered Species - Peary caribou
RE: Mike Ferguson's response to a Reuters report regarding Peary caribou and climate change
In an effort to point out the distortion of some facts in a recent media release (ECOLOG-L, 20 October, 1998), Ferguson stated the following.
"A reconnaissance survey by A. Gunn in 1998 indicated good calf production in summer 1998 (i.e., the population is not currently 'dying off', although its road to recovery will be long)." (Ferguson, 28 October, 1998, in submission to ECOLOG-L).
Ferguson's judgment, i.e., that "... the [Bathurst Island Peary caribou] population is not currently 'dying off', ..." may be misinterpreted by readers to mean that all is well and that there is no need for further concern. I believe that this is far from the truth.
Point 1. Population Trend
His unjustified conclusion that "the population is not currently 'dying off'" - could only be construed as obtusely correct, if he meant that the population will not likely become extirpated in 1998. If that was the intent, the distinction should have been clarified but, unfortunately, it was not. In the longer term, the conclusion that "the population is not currently 'dying off'" is premature. However, after examining the available data, it is clearly inappropriate to apply the term "currently" to the conclusion that "... the [Bathurst Island Peary caribou] population is not currently 'dying off', ..." just because there is still a handful of animals alive this year, even if some are calves of the year. Such a single-year consideration is simply illogical in terms of a meaningful temporal scale, especially when 1998 was preceded by 3 consecutive years of major to catastrophic losses.
In 1993, we counted 2400 Peary caribou within the Bathurst Island complex and 1719 of them were on northeastern Bathurst Island. In 1998, however, we counted only 43 caribou in total and, with an equal amount of search effort as in 1993, we saw only 39 on northeastern Bathurst Island - a 44-fold decrease. We estimate that the entire population in the Bathurst Island complex declined by about 97%, in a mere 3 years, from 1994 to 1997 and remains below 100 animals, based on the 1998 count.
Ferguson's assessment that "its road to recovery will be long" is, however, accurate. The people of Resolute on Cornwallis Island, the only human occupation in that region of the High Arctic, are currently without a readily accessible caribou population that can sustain any harvest. But it is critical that the Peary caribou in the Bathurst complex should not be harvested probably for 1-2 decades, if the population is to have its best chance of recovery. Clearly, at such a low number the slightest additional environmental pressure would be likely to drive the population to a point where recovery would be unlikely.
Point 2. Significance of Calves
All that the 1998 observation by Gunn, Dragon and Miller of 15 calves among 43 caribou tells us with certainty is that the autumn, winter, spring, and early summer of 1997/98 were favorable to calf production and early survival. Production of a few calves in one summer does not indicate even the beginning of a reversal of a downward trend or a realized state of recovery. No-one knows whether the net change in population size in 1998 was positive or negative. Similarly, no one knows how many 1+ yr-old caribou have been lost from the population in 1998 or how many caribou including calves will be lost by calving time (June) in 1999, regardless of the cause(s). Until the 1998 calves have survived through their first full year of life, in summer 1999, they should not be considered as contributing to an increase in the total size of the population.
There is no guarantee that the 1998 calves will live through their first year of life let alone through the 2 or 3 years necessary before the females will be able to contribute to the breeding segment of the population. In some other years, a promising initial number of calves have survived through the first summer of life only to subsequently experience extremely poor or nil survival to 1-yr of age (e.g., Miller, Russell and Gunn, 1977; Miller 1997).
Point 3. Future Weather and Wolf Predation
Perhaps, more importantly, no one can justifiably assume that future years will necessarily be consistently favorable for subsequent calf production and survival. Although not yet substantiated, preliminary meteorological data collected by the Atmospheric Environment Service weather station at Resolute, Cornwallis Island, suggest that the winter of 1998/99 may be unfavorable for caribou. In addition, additional mortality factors, such as predation and/or disease/parasites could come into play at any time, especially if the animals are in poorer physical condition. At present, we have no way of predicting the probability or severity of such potential events.
Because they are now at low numbers, the remaining caribou and muskoxen on the south-central Queen Elizabeth Islands, will be particularly vulnerable to wolf predation. It remains to be seen whether those remnant populations can survive the pressures of predation as a mere two wolves could remove more than all the apparent 1998 calf production each year and several wolves could make serious inroads annually into the remaining numbers of older animals. Unless the wolves on those islands suffer a total die-off or all of them abandon those hunting grounds this year for more productive areas elsewhere, it is quite possible that the Peary caribou (and muskoxen) on some or all of the south-central Queen Elizabeth Islands could be extirpated in the not too distant future.
Carcasses resulting from extreme undernutrition in winters 1994/95 through 1996/97 provided food for wolves and may have sustained more wolves than expected, judging solely from the numbers of surviving caribou and muskoxen. Wolves are known to have whelped and reared pups in the presence of abundant carrion in, at least, 1996 (personal observations). Studies indicate that numbers of wolves are correlated with the biomass of the prey species (e.g., Fuller 1989). The presence of viable pups in summer 1996 indicates that wolves within the Bathurst Island complex were still experiencing favorable conditions (abundant carrion) despite a major overall reduction in the size of the live prey base. This lag in the response of wolf numbers (including ongoing pupping), in relation to the drastic rapid decline of the live prey base, will still constitute a significant threat to the survival of caribou and muskoxen, even if weather conditions improve.
While it is true that Peary caribou have previously declined and recovered, we cannot assume that this will be the case this time. The major threat of global warming is predicted to continue or intensify; therefore, we cannot conclude this time that the recovery of the Bathurst Island Peary caribou population is a certainty or even likely.
In summary, it is premature to conclude that the presence of calves among the Peary caribou of the Bathurst Island complex is an optimistic omen for the survival of this population. The drastic and unpredicted decline in number from about 3000 to less than 100, in a period of only 3 years, and the continued presence of other threats to their survival, clearly indicates this population is imminently threatened with extirpation. Thus, immediate management actions are urgently required to foster the population's chances of survival and to prepare for the worst eventuality. Complacency is not a substitute for conservation.
Frank L. Miller
Research Scientist Emeritus Canadian Wildlife Service/
Research Associate Arctic Institute North America
E Mail: Frank.Miller@ec.gc.ca
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