Last week, I wrote an Opinion Piece called ‘Give the Bears a Break’ for the Winnipeg Free Press
Dr. Ian Stirling subsequently responded and dismissed by concerns. Essentially citing the fact that I have no scientific background and am therefore not qualified to express my opinion. He also cites a recent study by the IUCN Polar Bear Specialist Group (led by Amstrup, Stirling and Derocher)… not that I have been able to locate this paper as of yet.
Anyway, for what its worth, here is my scientific response to Ian Stirling… I don’t know if it will get published or not…
As Dr. Ian Stirling so eloquently pointed out in his response to my op-ed ‘Give the Bears a Break’, I do not have a scientific background. So, to keep this brief, I will cite someone who does: Mark Cattet.
Cattet is the most respected expert on bear drugging and handling procedures in North America; basically the guy who teaches Conservation officers and researchers how to do this stuff. In 2008, he published a study entitled ‘Long-term Capture Effects in Ursids’. It focused on grizzlies and black bears, however, the results are intended to apply to all bear species.
In his words, ‘body condition of bears captured more than two times tended to be poorer than bears captured once only, with the magnitude of effect directly proportional to number of times captured and the effect more evident with age.’
The study finds that body condition in grizzlies decreases by 11-15% if handled three times, and up to 25% in bears handled five times over their life cycle. Approximately one-third of the bears were found to have been handled between 2-8 times. I would venture a guess that Churchill’s polar bears may even have a higher rate of handling over their lifetime.
Stress hormones exceeded acceptable levels in 15-18% of all helicopter encounters. Movement rates of the grizzlies declined by 20% after drugging and handling and there was evidence of general (but not severe) muscle injury.
The study also notes that most research into this area has no effective means of determining actual mortality/survival rates nor have any of these papers actually looked at the mid-range effects of handling on these bears.
It appears that capture and handling effects may have a much longer duration than generally recognized, both physically and on behavior. These effects may last days or even weeks.
Now, this is far from someone ‘out to get’ science or a ‘denier’ or whatever people are labeled as these days. This is THE expert in handling bears, someone who cares deeply about these animals and wants to see things done right. Naturally, the results of this study were ‘imperiously sniffed’ at by certain researchers.
There is no doubt that Stirling’s research has been important and there is absolutely a correlation between spring ice and polar bear health. We also know that these conditions have worsened over the last thirty years. However, I would like to suggest, that when you add the cumulative effects of a sustained, semi-annual helicopter-research program, this population that is ‘on the edge’ is now, in fact, being pushed beyond the breaking point.
Here are some things we have ‘proven’:
- drugging and handling of polar bears in the fall results in lower birthweights for the female cub (Lunn and Stirling, 2004)
- heavier cubs are more likely to survive their first spring to summer period on the ice (Ramsay and Stirling, 1988, Stirling and Derocher, 1996)
- birthweights and cub health are linked to date of first reproduction (Kingsley et al 1988, Stirling and Derocher 1998)
- females, specifically, are more likely to become large adults if their birthweight is higher (Atkinson et al, 1996)
- heavier females have larger cubs and litters (Stirling and Derocher, 1994)
- from 1980-2004, female body condition declined by an average of 65kg (Cook et al, 2007)
- from 1984-2004, there were over 4,700 ‘handling’ events in this population of roughly 1,000 bears (within Wapusk National Park and Churchill area)
So, over 80% of our bears have been handled as part of this ‘intensive’ research program… now consider that only females are radio-collared, only females are ‘site-specific’ (more likely to be handled multiple times) and only females with new cubs are handled in the spring survey work (at their lowest weight and time of highest energetic stress).
Stirling seeks to discredit my ideas by citing a long-term decline in condition of Southern Hudson Bay bears as well – the direct neighbours of Churchill’s bears. While it is amusing that he feels comfortable citing research with a 20-year gap in data, it should also be noted that this Southern population has not declined by 22% as is reported from Western Hudson Bay. This population remains relatively stable.
If they generally have the same hunting conditions, same poor ice years, same warming climate yet one population is in ‘free-fall’, is it really so preposterous to question whether 30 years of ‘intensive’ handling is not even a factor? Why not just stop for five years to be absolutely sure?
To quote Cattet’s conclusion, ‘Significant capture-related effects may go undetected, providing a false sense of welfare of released animals. Further, failure to recognize and account for long-term effects of capture and handling on research results can potentially lead to erroneous interpretations.’
Something to think about.
Again, just to be clear. Life would have been much easier for Cattet not to express these concerns, his works does benefit from radio collars and handling directly… as does the IUCN Polar Bears Specialist Group. Strangely, the 2010 study that Stirling cites is not listed on the actual IUCN Mark-Recapture page…
Essentially, you now have two schools on Mark-Recapture effects – one from Mark Cattet (2008), who raises long-term concerns and recommends less-invasive techniques, and Steve Amstrup (2005), who finds no effects and is actively working with PBI/WWF to develop new radio collar programming and technologies.