Grizzly population story questionable
To the Editor:
The High Prairie South Peace News article “More Bears than anybody thought” – April 14, 2021 (The same article, with a different headline, appeared in the April 7 Slave Lake Lakeside Leader) would have the reader believe that as a result of improved scientific capacity to measure grizzly bear populations, the numbers of grizzly bears in parts of Alberta has doubled over the last decade.
According to the writer, previous grizzly bear estimates “involved a lot of guesswork.” But now, thanks to FRI research, there’s a “first ever scientific estimate of this area.”
The 66-page report is easily found using Google, and is worth reading for anyone interested in grizzly bear research. It used DNA-evaluated hair samples – collected over a three-month period – to create a population estimate.
And, it evaluated this data against several other Alberta Bear Management Area studies.
I am not a biologist. However, one would have to be extremely naive to believe that any study of grizzly bears, based on only three months of “field work”, followed by 33 months of lab analysis hampered by “funding challenges,” could possibly generate a reliable population estimate.
And in fact, the report suggests that in BMA 7 (Swan Hills), “we estimated that there were 12.6 bears per 1,000 km2 and 118 (CI= 62 – 226) bears living in the area. However, the precision of these estimates was low, suggesting that they should be interpreted cautiously.
We note that the lower bound of the CI is 62, which corresponds to the estimate of bears if we use detection rates found in other BMAs.
What does CI mean?
CI stands for confidence interval. In these vast, remote areas, it’s impossible to count every single bear and know for sure that we haven’t missed one. So, we detect as many as we can and then use statistics to estimate what the real population is.
The statistics tell us the estimated number of bears (the point estimate) as well as how confident we can be in that estimate.
So, for BMA 7, (CI=62–226) means that if the study was done over and over again, then 19 times out of 20, they’d get a point estimate of between 62 and 226 bears. Hardly accurate, yes? The writers of this article should have reported this.
Grizzly bears are among the slowest reproducing mammals in North America. Yet, according to this article, an area east of Banff, and, an area in the Yellowhead Region, report a doubled population estimate in 10 years. Again, one should seriously question the accuracy of this statement. Did populations actually double, or, were the previous estimates simply seriously flawed? Or, is the new data lacking confidence?
What tweaked my interest in this article was the accompanying photograph of a bear – with a caption below that reads “The grizzly bear population in Swan Hills is higher than experts thought.”
The bear in the photograph is not a grizzly bear. It is a colour phase black bear. If I was either the writer of this article, or, the person in charge of the research project, I would be extremely embarrassed to have a photograph of a black bear representing my “first ever, scientific” grizzly bear study.
Wildlife management is an extremely challenging task – especially for “iconic” species like grizzly bears, wolves, caribou, and some others. To be effective, it demands the best scientific data available, as well as contributions from a well-informed public. This article accomplishes neither.
Salt Prairie, AB