Category Archives: Life History

Spring ice alarm deflated – 2015 ice now as high as 2014 & Davis Strait highest since 1971

Arctic ice extent (at 14.1mkm2) on 15 April, was virtually identical to 2014 on that date, and higher than 2006. But the record goes to Davis Strait, which recorded the highest ice extent since 1971 for the week of April 16, while the waters of Eastern Newfoundland to the south (where most harp seals have their pups) had the third highest ice extent since 1969. Lots of fat baby seals are just what polar bears need at this time of year.

Harp seal pup_DFO Newfoundland

Continue reading

Tracking polar bears in the Beaufort Sea – March 2015 map

Here is the March 2015 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.”

putting_collar_on_polar_bear_slider_USGS

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 March 2015 is copied below.

Three out of eight female bears tagged in the Southern Beaufort Sea were in the Chukchi Sea subpopulation region during March – not surprising, many bears cross this “boundary.”
Continue reading

Superb sea ice conditions for polar bears worldwide during their critical feeding period

Prognosis, excellent. The sea ice hunting platform that polar bears require is everywhere and Davis Strait ice extent is the fourth-highest it’s ever been at this time of year.

Sea ice extent global 2015 April 2 NSIDC with anomaly WUWT

The spring feeding period is a messy, brutal business – many cute baby seals will die as polar bears consume 2/3rds of their yearly food supply over the next few months (April – June/early July), while sea ice is abundant.

Arctic marine mammals_Dec 31 2014_Polarbearscience

That leaves the remaining 1/3 of their energetic needs to be met over the following 9 months (most of it in late fall (late November/December) and hardly any during the summer months, regardless of whether the bears are on land or out on the sea ice) or over the winter. Continue reading

Polar bear consumption of terrestrial foods – new paper misses the point

A new paper by polar bear biologists (Rode et al. 2015) argues that terrestrial (land-based) foods are not important to polar bears now and will not be in the future – a conclusion I totally agree with – but they miss the point entirely regarding the importance of this issue.

Fat bears on land in the Southern Beaufort, Sue Miller photo, well-prepared for a brief summer fast.

Whatever food polar bears consume in the summer – whether they are on land or on the ice – doesn’t really matter. What matters is how many fat-rich seals they can consume between March and June each year. The fat put on in late winter/spring from gorging on baby seals carries polar bears over the summer, no matter where they spend it.

USGS polar bear biologist Karyn Rode and colleagues (press release here) have tried to frame this issue as one about future survival of polar bears in the face of declining sea ice. However, the fact that polar bears in the Chukchi Sea and Southern Davis Strait are thriving despite dramatic declines in summer sea ice (aka an extended open-water season), proves my point and disproves their premise. Bears in these regions are doing extremely well – contrary to all predictions – because they have had abundant baby seals to eat during the spring (see here and here).

Continue reading

Polar bear habitat update – even more ice this week in the Barents Sea

Polar bear habitat is close to average for this date all over the Arctic this week. Barents Sea pack ice has increased substantially since last week and the ice in Eastern Canada is still well above average (and higher than 1979-early 1980s). Arctic ice has grown since a preemptive call for “the lowest maximum extent on record” was made by NSIDC last week — there is now at least as much ice for this date as there was in 2011 and almost as much as there was last year (2014).

Polar Bear Breaks Ice

Southern Davis Strait polar bears are out feeding on the glut of harp seals in the pack ice off Labrador and Newfoundland (discussed in detail here). One or more bears strayed a bit from the pack and ended up swimming around near the Hibernia oil platform (not far from the ice edge, although the CBC reports didn’t mention that “minor” fact), discussed in this recently updated post (with maps).

Harp seal female with nursing pup, DFO Canada.

Harp seal female with nursing pup, DFO Canada.

Ice maps and graphs below: it’s worth a look.
Continue reading

Polar bear visiting Hibernia oil platform off Newfoundland was not far from sea ice

Perhaps the folks on the platform couldn’t see it, but sea ice wasn’t far off on Monday when a polar bear came to visit the Hibernia oil platform southeast of St. John’s, Newfoundland. See the map below (composite from Heritage Newfoundland and Canadian Ice Service):

Hibernia platform and sea ice at 23 March 2015_Polarbearscience
UPDATE 26 March 2015: Ian Stirling has added his expert comment on this incident, see below.

UPDATE 28 March 2015: Newfoundland’s Director of Wildlife has commented on this incident, see below.
Continue reading

Polar bear habitat update – more spring sea ice around Svalbard than 2014 & 2012

Polar bear habitat for the last week of March is well above average in eastern Canada for the second year in a row. The very low extent of ice in the Sea of Okhotsk – which has contributed strongly to the low maximum extent this year – is irrelevant to our discussion, since no polar bears live there.

Polar_Bear_male_Regehr photo_March 21 2010_labeled

There is a bit more concentrated ice around Svalbard than last year (or in 2012), although ice in the Barents Sea in general is still below average due to the state of the Atlantic Multidecadal Oscillation (AMO). The state of the AMO and its effects on Barents Sea polar bear sea ice habitat has nothing to do with global warming: it’s a cycle that has been documented for centuries (Miles et al. 2014).

Still, there is plenty enough sea ice for polar bear hunting: this is the beginning of the critical feeding time for all polar bears (see here and here), but especially for the survival of new cubs-of-the-year, so I have a few words about Western Hudson Bay cubs below.

Have a look for yourself.
Update: Added 20 March 2015, comparison maps from Cryosphere Today for 2006 vs. 2015.
Continue reading