Hey there, time traveller!
This article was published 1/3/2013 (1488 days ago), so information in it may no longer be current.
In his Feb. 26 column, Give the polar bears a break, Kelsey Eliasson recommends that polar bears be "given a break," by which he means stopping research, especially near Churchill. He incorrectly alleges that using a helicopter to capture bears for research has detrimental effects on the animals.
Several studies published in peer-reviewed scientific journals have addressed that question, including one a year ago by the International Union for Conservation of Nature polar-bear specialist group. None detected any significant negative effects on the key categories of survival or reproductive success.
Sadly, that does not stop Eliasson (who has no scientific training) from sniffing imperiously that he has "some issues with these papers, but let's leave that for another time."
Eliasson incorrectly refers to a study co-authored by me and three others, suggesting it documents negative effects on adult females. In fact, it reports that adult females tagged at their maternity dens in the fall moved to another location for the winter but that there was no negative effect on either their reproductive success or survival.
That study, however, cites an earlier one done in the mid-1980s by me and one of my graduate students in which we reported no significant negative effects from handling on bears of any age and sex class except for adult females.
We were puzzled at the time, because although recaptured adult females weighed less than they did when captured a few years earlier, they were not different in weight from previously unhandled adult females captured in the same year.
Now, however, because of the careful long-term research that Eliasson would like to see stopped, we know that because of climate warming, breakup of the sea ice in western Hudson Bay is already three weeks earlier than it was only 30 years ago and freeze-up is later. This has resulted in less time for the bears' all-important hunting of young seals on the early-summer ice and necessitates their living on their stored fat reserves through the open-water season for ever longer periods of time.
The result has been declines in polar bear reproduction, survival and the body condition of animals in all age and sex classes. This particularly affects adult females because they must share whatever they catch with dependent cubs for up to 21/2 years. Clearly, what we detected in the 1980s were the first negative effects of climate warming on the bears, but it was too early to realize what was happening.
Another strong piece of evidence comes from northern Ontario. In the 1980s, several hundred bears were tagged in a large population study. In the 2000s, there was another large tagging program. Despite a 20-year break between the two studies, bears of all age and sex classes in Ontario showed exactly the same statistically significant declines in body condition as do the bears in Manitoba. Clearly, the differences in both areas did not result from handling.
Department of biological sciences
University of Alberta