Tag Archives: freeze-up

W Hudson Bay polar bear season wrap-up: problem bear stats & sea ice vs. 2016

This year, due to an early freeze-up of the sea ice, many polar bears left the Western Hudson Bay area (including Churchill) the week of November 6-12. However, the folks who produce Churchill’s problem polar bear statistics did not generate a report for that week, so we are left with assessing the final freeze-up situation based on the previous report (see it here) and the one they have just released for the week of 13-19 November (below), the 18th week of the season (which began July 10):

Churchill Polar bear alert report Nov 13-19_Nov 20 released

The “quiet” week was almost certainly due to the fact that very few bears were still around, having left the previous week.

While it is apparently true that a south wind briefly blew ice away from the area around the town of Churchill, most bears had left by that point and there was plenty of ice to the north and southeast for bears that had congregated outside the town to wait for the ice to form.

Churchill sits on a point of land (see map below) that makes new ice vulnerable to winds from the south but this year impact was small: the north winds returned within a few days and so did the ice.

Hudson Bay weekly ice stage of development 2017 Nov 20

By this week there were still a few stragglers that hadn’t left shore but most of these were mothers with cubs, as well as young bears living on their own, who often hold back to avoid dangerous encounters with adult males at the ice edge.

A few adult males that were still in excellent condition after 4 months ashore without food seemed in no particular hurry to resume hunting. In part, this may have been due to the rather foul weather prevalent since the first week of November (with howling winds, low temperatures and blowing snow much of the time).

You can see in the chart below just how much more ice there was for the week of 20 November compared to average — all those dark and light blue areas along the west coast of Hudson Bay (and east of Baffin Bay) indicate more ice than usual. Even Southern Hudson Bay has enough shore ice for bears to resume hunting. Foxe Basin (to the north of Hudson Bay) has less ice than usual (red and pink) but there is still enough ice for polar bears there to begin their fall hunting, as the chart above makes very clear.

Hudson Bay weekly departure from normal 2017 Nov 20

Freeze-up and bear movement offshore were about three weeks earlier this year in Western Hudson Bay compared to 2016, which made a huge difference to the number of problem bears in Churchill, see below.

UPDATE 23 November 2017: CIS ice chart for today showing the ice forming in the northwest sector of Hudson Bay

Sea ice Canada 2017 Nov 23

UPDATE 27 November 2017: Final problem polar bear report copied below, issued by the town of Churchill. As noted above, the fact that some bears remained onshore into last week was a very local anomaly not experienced over the rest of the region.

churchill-pb-reports_week-19_20-26-nov-2017_last-of-the-season.jpg

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W Hudson Bay freeze-up one of earliest since 1979, not “closer to average”

Tundra Buggy Cam_10 Nov 2017_bear headed offshore pmWestern Hudson Bay polar bears have been leaving shore for the rapidly thickening sea ice since at least 8 November (bear above was heading out 10 Nov.). However, Polar Bears International chose not to mention the unusually early freeze-up until the week-long (5-11 November) doomsday bombardment they call “Polar Bear Week” was almost over.

It’s worse than that: two days earlier, PBI’s activist spokesperson Steven Amstrup apparently told the Sierra Club (“People Show Up for Polar Bear Week, But the Ice Hasn’t Yet”; 8 November 2017) that “the bears are still waiting on shore for that ice to freeze” even though ice development had been well on its way for days at that point. As if freeze-up on 10 November came as a big surprise to him, with no warning whatsoever.

Apparently, they didn’t want their naive and gullible supporters to know at the beginning of Polar Bear Week that the sea ice loss of which PBI spokespeople rant about constantly (Save Our Sea Ice) was a total non-issue this year: breakup was not earlier than usual and new ice began developing off Churchill at about the same time it did in the 1980s (last week of October).

As I discussed last year regarding newly-published studies (Obbard et al. 2015, 2016) on the status of Southern Hudson Bay (SHB) bears:

“…SHB polar bears left the ice (or returned to it) when the average ice cover near the coast was about 5%. This finding is yet more evidence that the meteorological definition of “breakup” (date of 50% ice cover) used by many researchers (see discussion here) is not appropriate for describing the seasonal movements of polar bears on and off shore.”

That post (with its list of references) is worth another look for its discussion of the following points: the definition of freeze-up; the relationship of official freeze-up and breakup dates to the dates that bears depart; the overall health and survival of Western and Southern Hudson Bay polar bears.

Hudson Bay North daily ice stage of development 2017_Nov 10

Below I dissect the misinformation that PBI calls “science communication” in their attempt to minimize the damage caused by this early freeze-up to their message of looming catastrophe for polar bears.

Bottom line: Not only was freeze-up early this year, 2017 will go down as one of the earliest WHB freeze-up years since 1979 and for Southern Hudson Bay bears as well, since as of 13 November there is concentrated ice all the way into James Bay.

Sea ice Canada 2017 Nov 13

UPDATE 14 November 2017: CBC Radio broadcasted an interview yesterday with a recent visitor to Churchill who was remarkably candid about what he saw regarding polar bears, sea ice, and what he heard from locals about freeze-up (“the earliest since 1991”). It corroborates what I’ve reported here. Worth a listen (about 8 minutes):

“Brian Keating: Polar bears in Churchill, Manitoba” (The Homestretch, November 13, 2017, Season 2017, Episode 300312418)

The closest Doug Dirks has come to seeing a live polar bear was at the Calgary Zoo many moons ago. But naturalist Brian Keating has just returned from another trip to Churchill, Manitoba. He joined Doug Dirks with the details of that frosty adventure.

http://www.cbc.ca/player/play/1095183939998

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Experts talk of their bleak future, W Hudson Bay polar bears get earliest freezeup in decades

It seems that Churchill residents and visitors woke up this morning to find most local polar bears had left to go hunting — on the sea ice that supposedly doesn’t exist. Right in the middle of the Polar Bear Week campaign devised by Polar Bears International to drum up donation dollars and public sympathy for polar bear conservation!

Polar bear on the sea ice_Churchill_8 Nov 2017_Explore dot org cam my photo 2Frigid temperatures and north winds last night helped the process along, but this early freeze-up has been in the works for almost a week. From what I can ascertain, it appeared the only bears around onshore today were a mother with her young cub moving out towards the ice (females with cubs are usually the last to move offshore, probably to reduce the risk of encounters with adult males who might kill the cubs).

Tundra Buggy cams at Explore.org have been showing markedly fewer bears today and those that have been seen were on the ice (see above and below) or heading out to it.

The chart below is for yesterday (7 November), before the cold and north winds hit the region. It shows the concentration of ice that’s >15 cm thick.

Hudson Bay North 2017 concentration Nov 7

The chart for 8 November is below, after the storm.

Hudson Bay North daily ice concentration 2017_Nov 8

This is ice thick and extensive enough for polar bears to go hunting. Some bears almost certainly left shore yesterday, with the rest following quickly on their heals today. There are sure to be some stragglers left ashore that will leave over the next few days but the fact remains: there is sea ice to be had for those polar bear willing to start hunting.

Watch polar bear on the WHB sea ice below (screen caps below – and one above – were taken the afternoon of 8 November, from the Tundra Buggy Cam live feed near Churchill).

Polar bear on the sea ice_Churchill_8 Nov 2017_Explore dot org cam my photo 3

Keep in mind that in the 1980s, bears left for the ice on 8 November, on average. That means we’re back to a 1980s freeze-up scenario, at least for this year.

Funny how no one bothered to mention the potential for an early freeze-up to the media last week, when scientist were so eager to talk about the imminent demise of WHB bears. And funny that Polar Bears International hasn’t tweeted a word today about the famous Churchill bears having enough sea ice to go hunting, smack in the middle of Polar Bear Week.

Yes, the “Save Our Sea Ice” PBI rallying cry sounds a bit hollow with sea ice as far as the eye can see off Churchill today. But will anyone in the mainstream media point out the irony?

See charts below for years back to 2004, on this date (2005 missing for some reason), to compare to the above 8 November image (2004 is as far back as the archive goes).

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Problem bear report for Churchill might be second-last one this year

Good news for Western Hudson Bay polar bears that have been getting into trouble in Churchill, Manitoba: the seasons looks to be almost over.  Only a few more days of “Polar Bear Week” likely remain, as sea ice will build along the shoreline in response to severe cold and the north winds expected later today.

Churchill PB reports_week 17_30 Oct- Nov 5_2017_week 10 and 13 missing

This morning near Churchill, from one of the tundra buggies, post at Explore.org:

Churchill on 7 Nov 2017_Explore dot org

Churchill weather 2017 Nov 7

Sea ice at 7 November, will be updated so check back:

Sea ice Canada 2017 Nov 7

Ice forming all the way into James Bay (Southern Hudson Bay), as shown by the daily ice concentration charts for 7 November 2017 (Northern and Southern Hudson Bay) of ice thicker than 15 cm:

Hudson Bay North daily ice concentration 2017_Nov 7

Hudson Bay South daily ice concentration 2017_Nov 7 greater than 15 cm

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Early freeze-up in progress on Hudson Bay – what a difference a year makes

In contrast to 2016, when freeze-up along Western Hudson Bay was about as late as its ever been (early December), ice is already forming along the shore of northern Hudson Bay. There is much more ice than usual for this date, indicated by the dark blue in the latest weekly ice chart below:

Hudson Bay weekly departure from normal 2017 Oct 30

The ice is still thin, as the chart below indicates, but that’s how freeze-up starts. As long as strong winds don’t blow the ice away (as it sometimes does at this stage), the ice gets thicker day by day — and advances further and further off shore. Polar bears get out on the ice as soon as they are physically able, when the ice is about 3-4 inches thick (about 10 cm) or less.

Hudson Bay North daily ice stage of development 2017_Nov 1

Below is a video of a bear traversing that thin ice yesterday (1 November 2017), near Churchill. Is this a portend of a freeze-up date as early as occurred in the 1980s?
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Breakup of sea ice on track in Canada as critical feeding period for polar bears ends

Relative to recent years and potential impacts on polar bear health and survival in Canada, there is nothing alarming in the pattern or speed of sea ice breakup for 2017, either over Hudson Bay, the southern Beaufort, or the eastern high Arctic.

Sea ice Canada 2017 June 8

Last year at this time (see map below), there was more open water in Hudson Bay and in the Southern Beaufort yet the polar bears came ashore in fine shape that summer and there was no hue-and-cry of dying bears anywhere. Breakup this year is on track to be about 3 weeks earlier than it was in the 1980s, as it has been since at least 2001, a conclusion reached by polar bear specialists (Castro de la Guardia et al. 2017; Lunn et al. 2016), who examined sea ice breakup to 2015.

Sea ice extent Canada 2016 June 8 CIS

Here are critical words to remember (more details here) from biologist Martin Obbard and colleagues (2016:29) on the relationship between body condition and sea ice for Southern Hudson Bay (SH) polar bears, which apply equally well to bears in other regions:

Date of freeze-up had a stronger influence on subsequent body condition than date of break-up in our study. Though models with date of freeze-up were supported over models with other ice covariates, we acknowledge that lower variability in freeze-up dates than in ice duration or break-up dates could have influenced the model selection process. Nevertheless, we suggest that a stronger effect of date of freeze-up may be because even though break-up has advanced by up to 3-4 weeks in portions of Hudson Bay it still occurs no earlier than late June or early July so does not yet interfere with opportunities to feed on neonate ringed seal pups that are born in March-April in eastern Hudson Bay (Chambellant 2010). Therefore, losing days or weeks of hunting opportunities during June and July deprives polar bears of the opportunity to feed on adult seals, but does not deprive them of the critical spring period (Watts and Hansen 1987) when they are truly hyperphagic. No doubt, the loss of hunting opportunities to kill adult seals has a negative effect on body condition, but it appears that for bears in SH a forced extension of the fast in late fall has a greater negative effect on subsequent body condition.” [my bold]

In other words, by mid-June at least (maybe earlier), polar bears have largely finished their intensive feeding that’s so critical to their survival over the rest of the year.

That’s why the latest count of SH polar bears (Obbard et al. 2015) showed a stable population (and see this recent post on WHB polar population estimates). But freeze-up was late last year and that’s what will make the difference to polar bears over the coming year.

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New paper updates lack of trend in W Hudson Bay breakup/freeze-up dates to 2015

A newly-published paper shows that there has been no trend in the time Western Hudson Bay polar bears spent onshore between 2001-2015 due to sea ice conditions at breakup or freeze-up (previously available to 2010 only), despite the marked decline of global sea ice since 2007.

castro-de-la-guardia-et-al-derocher-2017-fig-3-no-caption

Figure 3 from Castro de la Guardia and colleagues (2017) showing freeze-up and breakup dates and ice-free days 1979-2015 for Western Hudson Bay. Figure with caption, copied below, explains symbols.

Previously, a 2007 paper by Eric Regehr and colleagues for WHB bears up to 2004, which was used to support the US bid to list polar bears as ‘threatened’ with extinction, concluded that between 1984 and 2003, bears were spending 3 weeks longer onshore than they did in the 1980s.

The big news from Castro de la Guardia et al. (2017) is that polar bears spent longer onshore from 1979-2015 by … 3 weeks. That is, no change from the situation in 2004. Wow!

Note the population size of the entire WHB subpopulation has also not declined since 2004 and is currently estimated at about 1030, based on a 2011 aerial survey (Stapleton et al. 2014).

Thanks to Andrew Derocher for the heads-up tweet.

From the abstract (my bold):

We found that the ice-free period in this region lengthened by 3 ± 0.8 wk over the period 1979−2015. Polar bears migrated onshore 2 wk earlier and offshore 1 wk later in the period 2005−2015 than in 1980−1989.

Here is the region in question, illustrated by Fig. 1 from the paper:

castro-de-la-guardia-et-al-derocher-2017-fig-1a-locationThe significant information contained in this paper is breakup and freeze-up dates and length of the ice-free period data for 2010-2015, which has been unavailable until now. More excerpts and comments below, including Figure 3 with its caption. Continue reading