Category Archives: Sea ice habitat

Churchill polar bear report 24-30 July rather boring compared to last year

This is the third week of reports from the Churchill Polar Bear Alert Program but not much in the way of excitement or information, although more bears must be ashore by now.

Churchill PB reports_week 3_ July 24-30_July 2017

Compare to last year at this time, when there was much more activity:

2016 July 25_31_week 3

There was still some thick ice lingering off the coast of Western Hudson Bay last week, as this weekly ice chart shows:

Hudson Bay ice weekly stage of development 2017_July 24

Churchill polar bear report 17-23 July 20: those ashore appear to be in great shape

Just out from the City of Churchill: few polar bears reported onshore for the week of 17-23 July 2017 (week 2) but those seen “appear to be in great shape.”
Churchill PB reports_week 2_ July 17-23_2017

Update 24 July 2017 12:20 PM: Just spotted this blog report from Churchill Polar Bears” that I somehow missed last week, which includes what seems to be the first polar bear photo’s of the season (of a sow and two chubby cubs) that are also in fine condition.

ChurchillPolarBearsDotOrg_July 14 2017 Alex De Vries photoThe photos were taken by Churchill photographer and guide Alex De Vries on Thursday 13 July and I hope he doesn’t mind my including one of those here as documentary evidence of the good body condition of this mother and both her cubs — see more photos at the Churchill Polar Bears blog post dated 14 July here.

Compare last week’s PB Alert report above to last year’s (below):

2016 July 18_24_week 2

Problem polar bears of Churchill: first report of the season similar to 2016

The first activity report of the Churchill Polar Bear Alert Program has been released for 2017. It comes on the same week as last year’s (so about the same dates for first bears ashore both years), and reports pretty much the same activity.

Churchill PB reports_week 1_ July 10-16_July 2017

Odd that this year’s report contains no mention whatsoever of the condition of the bears as did last year’s (see below), which may have brought criticism for spoiling the media ‘message’ that WHB bears are suffering because of reduced sea ice. Better no comment at all than good news, eh?

Sea ice for the week of 10 July off Western Hudson Bay this year consisted of a broad strip of thick first year ice (>1.2m thick) just off shore.

Hudson Bay weekly ice stage of development 2017 July 10

The ice charted above looked like this on a standard ice map:

Sea ice Canada 2017 July 11

There are no other reports that I could find of polar bears ashore along the coast of Western Hudson Bay, so these bears must be the first wave.

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Western Hudson Bay polar bears reportedly still on ice as of 17 July 2017

Today, polar bear biologist Andrew Derocher posted a progress report via twitter on the annual journey ashore of the Western Hudson Bay bears tagged by his University of Alberta research team that shows virtually all of the bears are still out on the sea ice.

Churchill_Polar_Bear_2004-11-15 Wikipedia

After months of gloomy reports on the state of the Hudson Bay sea ice, it’s clear from the map Derocher posted (below) that only one bear out of 12 still transmitting has come ashore so far, although he comments that “some tags haven’t reported lately” (the purple icons are ear tags put on males &/or young bears while the blue icons are collars put on adult females):

Oddly, the same comment was made almost a month ago about these same bears and the suggestion was made that these animals “may be swimming to shore”:

Money quote: Today Derocher remarked that “bears may be shifting behaviour to stay out on less ice” to explain why the tagged bears have still not come ashore as he expects them to do.

Perhaps if he used a different ice chart, it might make more sense (see below). However, the same thing has been happening year after year: WHB polar bears stay on the ice much longer than Derocher predicts but he does not change his expectations or the type of ice chart he uses to track the bears.

As I’ve pointed out before (because this is what field researchers have stated), polar bears have a tough time catching seals after about mid-June or so but they may still prefer to be on the sea ice than on land, even if it’s low concentration ice.

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Abrupt summer sea ice decline has not affected polar bear numbers as predicted

Yes, Arctic sea ice has declined since satellite records began in 1979 but polar bears have adjusted well to this change, especially to the abrupt decline to low summer sea ice levels that have been the norm since 2007.

Global pb population size sea ice 2017 July PolarBearScience

Some polar bear subpopulations have indeed spent more time on land in summer than in previous decades but this had little negative impact on health or survival and while polar bear attacks on humans appear to have increased in recent years (Wilder et al. 2017), the reasons for this are not clear: reduced summer sea ice is almost certainly not the causal factor (see previous post here).

Ultimately, there is little reason to accept as plausible the computer models (e.g. Atwood et al. 2016; Regehr et al. 2016) that suggest polar bear numbers will decline by 30% or more within a few decades: even the IUCN Red List assessment (Wiig et al. 2015) determined the probability of that happening was only 70%.

Arctic sea ice has never been a stable living platform (Crockford 2015): it shifts from season to season, year to year, and millennia to millennia. Without the ability to adapt to changing conditions, Arctic species like polar bears and their prey species (seals, walrus, beluga, narwhal) would not have survived the unimaginably extreme changes in ice extent and thickness that have occurred over the last 30,000 years, let alone the extremes of sea ice they endured in the last 200,000 years or so.

Some biologists continue to hawk doomsday scenarios for polar bears due to summer sea ice loss but the truth is that their previous predictions based on sea ice declines failed so miserably (e.g. Amstrup et al. 2007) that it’s impossible to take the new ones seriously — especially since the basic assumptions that caused the first predictions to fail have not been corrected, as I’ve stated in print (Crockford 2017:27):

In summary, recent research has shown that most bears are capable of surviving a summer fast of five months or so as long as they have fed sufficiently from late winter through spring, which appears to have taken place since 2007 despite marked declines in summer sea ice extent.

The assumption that summer sea ice is critical feeding habitat for polar bears is not supported.

Recent research shows that changes in summer ice extent generally matter much less than assumed in predictive polar bear survival models of the early 2000s as well as in recent models devised to replace them (Amstrup et al. 2010; Atwood et al. 2016a; Regehr et al. 2015; Regeher et al. 2016; Wiig et al. 2015), while variations in spring ice conditions matter more.

As a consequence, the evidence to date suggests that even if an ‘ice-free’ summer occurs sometime in the future ­ defined as sea ice extent of 1 million km2 or less (Jahn et al. 2016) ­ it is unlikely to have a devastating impact on polar bears or their prey. [my bold]

The abrupt drop in summer sea ice that occurred in 2007 was not predicted by experts to occur until mid-century yet the predicted decimation of polar bears worldwide expected under those conditions (a loss of 2/3 of the global total, to only about 6660-8325 bears) not only did not happen, it did not come even close to happening (Crockford 2017; see also my recent books, Polar Bear Facts & Myths, and Polar Bears: Outstanding Survivors of Climate Change, sidebar).

Instead, the global population grew from about 22,550 bears in 2005 to about 28,500 bears in 2015. And while this might not be a statistically significant increase (due to the very wide margins of error for polar bear estimates), it is absolutely not a decline.

The present reality is that low summer sea ice cover since 2007 has not caused polar bear numbers to decline and therefore, polar bears are not a species in trouble. This suggests that even if the Arctic should become briefly ice-free in summer in the future, polar bears are likely to be only minimally affected and not become threatened with extinction. Polar bears are outstanding survivors of climate change: recent research and their evolutionary history confirm this to be true.

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Polar bear attacks are extremely rare says new study — but the data are incomplete

I did considerable research on polar bear attacks for my thriller of a novel EATEN — which many readers are finding a welcome change from the numbers-and-statistics approach of science — and I have to say that a recently published scientific summary of this phenomenon (1880-2014) authored by biologist James Wilder and colleagues left me speechless (Wilder et al. 2017).

Isbjørn

with permission, see EATEN cover.

By attempting to generate information that could be assessed with statistical methods, the authors ended up with data that is so skewed and incomplete that it fails to provide a plausible assessment of the risk to humans of attacks by polar bears. In my opinion, acknowledging that well-reported attacks on Europeans (or recorded by them) make up the bulk of the data used in the paper does not adequately address the weakness of the authors’ conclusions that attacks by polar bears are “extremely rare.”

The paper also focuses much attention on the potential for increases in polar bear attacks on humans due to sea ice loss (blamed on global warming) but ignores totally the increased risk stemming from the larger proportion of adult males that now exist in protected populations. Adult males frequently steal the kills of younger bears and in recovering (i.e. growing) populations, relatively more adult males potentially generate more young males that are nutritionally stressed and at risk of attacking humans (see discussion below).

Finally, no supplementary data is provided to show which records of attacks were included in the study, and no information is provided about how to access the database. How is that possible in this day and age?

Much is made in the paper of the negative effect of polar bear attacks on conservation objectives and the perceived increase in attacks associated with recent sea ice loss. These points were picked up by activist organization Polar Bears International (“Save Our Sea Ice!“) in a press release issued yesterday (11 July, pdf here). This has already generated the desired media attention (here and here, likely more to follow, like this) which is predictably focused on predictions of more polar bear attacks on humans due to global warming.

I have a feeling Inuit and other native inhabitants of the Arctic will not be impressed.

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Polar bears of W Hudson Bay utilizing a substantial patch of thick first year ice

There’s been no word as yet, either from tour operators or polar bear researchers, that Western Hudson Bay polar bears have come ashore for the summer/fall season. Andrew Derocher reported at the end of June that the bears tagged by his team were still on the ice and as I write this, has not yet reported them ashore.

That pattern is consistent with the presence of thick ice along the west coast of the Bay — from well north of Churchill to the south of Wapusk National Park — for the last few weeks. The weekly chart for 3 July 2017 below from the Canadian Ice Service shows that virtually all of the ice remaining is thick first year ice (>1.2m, dark green on this map):

Hudson Bay weekly ice stage of development 2017 July 3

By the 9 July, the extent of this patch of ice was somewhat reduced but still a very prominent feature over the Bay, suggesting that if adult seals are using this ice as a refuge while molting, some bears may still be attempting to hunt even though their success rate may not be very high:

Sea ice Canada 2017 July 9

Bottom line: As has been the pattern for more than a decade, 2017 will not go down in history as an especially early year for WHB polar bears coming off the ice for the summer/fall season but instead may be as late as last year, when lots of bears were reported off the ice by mid-July at Seal River (just north of Churchill), all in excellent condition.

It remains to be seen if the condition of bears will be as good this year as they were in 2016, given the late start to the season. But it does mean that the lack of trend in breakup dates since 2001 continues: breakup of the sea ice in WHB since 2001 has been about one week later than it was before 1998 (Castro de la Guardia 2017; Cherry et al. 2013; Lunn et al. 2016).

If some polar bear struggle to survive this year it will be due to the late freeze-up date last fall combined with challenging winter conditions over Hudson Bay, not because of an early breakup of the sea ice.

And while it is certainly true that the overall trend in time spent onshore by WHB polar bears since 1979 has increased by about three weeks, the lack of a continued trend since 2001 is not what was expected or predicted, especially given the marked decline in global sea ice levels that have made headlines since 2007 (Crockford 2017), and the predictions of how devastating such low levels of ice would be to polar bears in areas like Hudson Bay that have to deal with a total disappearance of sea ice in summer and early fall.

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