Monthly Archives: October 2014

Declining polar bear weights and early breakup dates in WHB, Part I: What’s a starving bear?

Posted on October 10, 2014 | Comments Off on Declining polar bear weights and early breakup dates in WHB, Part I: What’s a starving bear?

The oft-repeated claim that polar bears are starving in Western Hudson Bay (e.g., here, here, here, and here) comes primarily from a 10 year old study that documented a declining trend in polar bear body condition (a biology euphemism for relative fatness) between 1980 and 2004, which appeared to correlate with earlier and earlier breakup dates for Hudson Bay.

Figure 1. Polar bear female with cub, 2009, Churchill, Western Hudson Bay. Wikipedia.

Figure 1. Polar bear female with cub, 2009, Churchill, Western Hudson Bay. Wikipedia.

The authors of that study (polar bear specialist Ian Stirling and NASA sea ice researcher Claire Parkinson) reported the body weights of lone female bears captured in Western Hudson Bay between 1980 and 2004. The trend over time in those bear weights was then correlated with the overall change in dates of sea ice breakup on Hudson Bay for that period.

However, it turns out that while the trend of body condition and the trend in breakup dates indeed correlated over time, the actual year to year data did not. The question is, what does that mean for the claim that polar bears in WHB are starving?
Continue reading

Comments Off on Declining polar bear weights and early breakup dates in WHB, Part I: What’s a starving bear?

Posted in Life History, Sea ice habitat

Tagged , , , , , , , , , , , ,

Mass haulouts of female Pacific walrus as a sign of population health

Posted on October 7, 2014 | Comments Off on Mass haulouts of female Pacific walrus as a sign of population health

Mass haulouts of female Pacific walrus and their calves in fall don’t happen all the time but they do occur. I recently pointed out (here and here) two instances of such incidents from the 1970s.

I said this provided evidence that the September 2014 incident reported in the media was not “a new phenomenon” for this region, as WWF spokepersons and Alaskan biologists have claimed (reiterated in this PBS interview).

Figure 1. Walrus females and calves hauled out on a beach in Svalbard, photo accompanying an October 6, 2014 news report in “Eye on the Arctic” of the rapidly increasing Atlantic walrus population there. (Photo: Thomas Nilsen/Barents Observer).

Figure 1. Walrus females and calves hauled out on a beach in Svalbard, photo accompanying an October 6, 2014 news report in “Eye on the Arctic” of the rapidly increasing Atlantic walrus population there. (Photo: Thomas Nilsen, Barents Observer).

One aspect of the recent occurrence of a large herd on an Alaskan beach that apparently needs reiterating is that the population of walruses declined rather markedly after a 1970s peak and has rebounded since. This suggests that huge herds of females and calves hauling out on beaches in the fall to feed might only be seen when the population is very large.
Continue reading

Comments Off on Mass haulouts of female Pacific walrus as a sign of population health

Posted in Life History, Sea ice habitat, walrus

Tagged , , , , , , , , , , , , ,

Tracking polar bears in the Beaufort Sea – September 2014 map

Posted on October 6, 2014 | Comments Off on Tracking polar bears in the Beaufort Sea – September 2014 map

Here is the September 2014 follow-up to my post on the July 2013 track map for female polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – “Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice.”

See that post for methods and other background on this topic, and some track maps from 2012 (also available at the USGS website here).

The USGS track map for September 2014 is copied below (Fig. 1).

At the end of September, with sea ice starting to rebuild, it appears there were 8 bears on the ice and three on land.

The situation for September was not very much different from August, except that two of the 11 bears (up from one) were on the ice in the Chukchi Sea in September, a phenomenon that was recently acknowledged to have affected the last population estimate for the Southern Beaufort subpopulation.

Continue reading

Comments Off on Tracking polar bears in the Beaufort Sea – September 2014 map

Posted in Population, Sea ice habitat

Tagged , , , , , , , , , , , ,

High walrus numbers may explain why females and calves are hauling out in droves

Posted on October 4, 2014 | Comments Off on High walrus numbers may explain why females and calves are hauling out in droves

Are the recent mass gatherings of females and calves on the beaches of western Alaska and the Russian Far East a sign that population are again close to the limit the habitat can support, as they were in the 1970s?

At the risk of belabouring the point that lack of sea ice does not seem to be a reasonable explanation for this phenomenon (see my last two posts, here and here, and Andrew Montford’s excellent additions here), I think this is a possibility that needs to be considered.

Walruses at Point Lay Sept 27 2014 NOAA CMDA0007_sm

2014 Point Lay, NOAA photo

Walrus are well protected in the US and Russia, and population numbers have risen again since the 1990s, after significant declines in the early 1900s and again in the 1980s.

A paper from the late 1980s suggests that a return to high population numbers may be a more plausible cause for mass gatherings of females and calves that lead to stampede deaths than does reduced sea ice due to global warming.

Have a look and see what you think. It may not be the only reason but it may be a major contributing factor.

Continue reading

Comments Off on High walrus numbers may explain why females and calves are hauling out in droves

Posted in Advocacy, Sea ice habitat, walrus

Tagged , , , , , , , , , , ,

Mass gatherings of walrus follow-up – sea ice maps for 1978 and 1972

Posted on October 2, 2014 | Comments Off on Mass gatherings of walrus follow-up – sea ice maps for 1978 and 1972

Walruses as polar bear prey and sea ice were on my mind last night and I remembered that we DO have detailed sea ice information for 1978 and 1972 – from the sea ice atlas put together by University of Alaska Fairbanks (UAF), which has ice concentration maps for Alaska going back to 1850 — and for every year up to 2013 (reported previously here).

Chukchi Sea walrus, June 2014. US Fish and Wildlife Service.

Chukchi Sea walrus, June 2014. US Fish and Wildlife Service.

I’ve copied some of the ice maps below.

It is clear that ice was available close to Wrangel Island in 1972 when walruses chose to haul out on the island in huge numbers. And in 1978, there was ice present to the north of the walrus herd, but they had moved away from the ice to get to St. Lawrence Island, where they hauled out in large numbers.

This means it is more likely that food resources were the issue, not sea ice.
UPDATE OCTOBER 3 2014:

See another interesting follow-up elsewhere: Walrus inconsistencies
Continue reading

Comments Off on Mass gatherings of walrus follow-up – sea ice maps for 1978 and 1972

Posted in Life History, Sea ice habitat, walrus

Tagged , , , , , , , , , , , , , , , ,

Mass haulouts of Pacific walrus and stampede deaths are not new, not due to low ice cover

Posted on October 1, 2014 | Comments Off on Mass haulouts of Pacific walrus and stampede deaths are not new, not due to low ice cover

Large haulouts of walruses — such as the one making news at Point Lay, Alaska on the Chukchi Sea (and which happened before back in 2009) — are not a new phenomenon for this region over the last 45 years and thus cannot be due to low sea ice levels. Nor are deaths by stampede within these herds (composed primarily of females and their young) unusual, as a brief search of the literature reveals.

Pt Lay map Google marked

The attempts by WWF and others to link this event to global warming is self-serving nonsense that has nothing to do with science.

UPDATE October 3, 2014: See below. Also, do see follow-up posts here, here, and especially, here.

UPDATE October 23, 2014: A briefing paper summary is here and a video version of that paper (“The Walrus Fuss” — 3 1/2 minutes long) here.

There is also a follow-up post on the situation here.

Continue reading

Comments Off on Mass haulouts of Pacific walrus and stampede deaths are not new, not due to low ice cover

Posted in Advocacy, Sea ice habitat, walrus

Tagged , , , , , , , , , , , ,