Polar Bear Blog – Numbers Game

So, I’m pretty tired of polar bear politics but the numbers being thrown around about Churchill’s polar bear population are starting to drive me a bit crazy.  So here we go…

In several articles, the number of 805 bears is being cited as the population estimate for Western Hudson Bay.  On paper, this is accurate, however, the context in which it is used is, I would say, purposely misleading.

In 2004, the official estimate for Churchill’s polar bears was listed as 935 animals, a significant decline from 1194 in 1987.  So, when the same scientists who have quoted ‘935’ bears now say there is ‘805’ bears, its pretty safe to say that the population is still in free fall.  Makes sense right?

BUT this is polar bears and nothing is ever simple with polar bears.  So when you actually take the time to sit down and read the new population study – lunn-et-al-2016-whb-survey-in-print-final– of course, you find that things are not quite what they seem…

Things get a bit tricky around page twelve… yes, page twelve.

‘Overall abundance declined from 1185 polar bears (95% BCI = 993–1411) in 1987 to 806 bears (95% BCI = 653– 984) in 2011. Since 2004, the last year of the previous demographic assessment (Regehr et al. 2007), there was no apparent trend in abundance (Fig. 6). The estimate of abundance for 2004 from the current study (742, 95% BCI = 630–872) is lower, although with overlapping confidence intervals, than the 2004 estimate (935, 95% CI = 794–1076) from Regehr et al. (2007).‘

Let me remove the quotes and sciency blah blah…

‘The estimate of abundance for 2004 from the current study (742) is lower… than the 2004 estimate (935).’

So when they changed the models, researchers also reduced the 2004 estimate by 193 animals.  To be clear, almost two hundred bears disappeared with the click of a button.  Oh well.

Everyone supports efforts to have the best estimates possible and use the best modelling techniques, however, if you then turnaround and use 800 bears without qualifying that number, it gives a very misleading impression.

 
<< >>

Despite what is being portrayed in the media, the western Hudson Bay population had a modest increase between 2004 and 2011, increasing from 742 to 805 animals (about 8%).

In fact, its safe to say that there was no statistically significant change in the Western Hudson Bay population between 1990 and 2011.  Mind blown!

If you add the 200 or so bears that were ‘removed’ from the model, you come up with 1000 animals.  The same estimate that the 2011 aerial survey found.  So it is very fair to say that the population of bears near Churchill is around 1000 animals.

Given local observations of cub productions, health and numbers, I would suggest that the population has continued to increase up to 2015-16.  I fully expect the aerial survey conducted this summer to report an increase to possibly 1150-1200 bears.

The data also tell us is that Western Hudson Bay polar bears seem to have significant mortality after a strong El Nino/La Nina event.  This is evident by drastic population changes, about 20% reductions, in 1989-90 and 1999-2000.

It is my opinion that another drop in population is coming this spring.  The weather this fall was very similar to the late freeze and early breakup after the 1998 El Nino.  It also seems that man-made climate change is exacerbating the effects of these El Nino/La Nina events.  This is not great news for bears.

More than ever, it is critical that management decisions be made utilizing an honest review of population data and not an emotional plea or activist science.  In my opinion, using the 800 bear estimate without quantifying it and implying that Western Hudson Bay continues to decline does not qualify as ‘honest’.

The problem is that a stable population in Western Hudson Bay does not fit the narrative.   This population was listed as ‘doomed’ a long time ago and many reputations seem to be riding on this prediction.   This is truly a shame.

To me, the message that these bears are adapting and surviving in a rapidly changing climate is much stronger than simply writing them off.  The bears are changing their lives, they are fighting and surviving in a changing world. This is an important message.  They are doing their part.  Is that not a stronger message than simply wringing our hands and patting ourselves on the back for trying to save these ‘poor creatures’?

4 thoughts on “Polar Bear Blog – Numbers Game”

Leave a Reply to Mike McIntosh Cancel reply

Your email address will not be published. Required fields are marked *