Breakup for Western Hudson Bay (WHB) is looking to be later than usual this year, given that the average breakup date since 1991 has been July 1 (using a 30% threshold) – only a few days from now – and the ice in WHB is nowhere near 50% coverage, let alone 30%.
Note that few WHB bears come off the ice around Churchill – most come ashore along the southwest coast of Hudson Bay (almost into SHB) and make their way north over the course of the summer to meet the ice as it reforms in the fall north around Churchill – that’s why it’s called a “migration.”
There’s still a lot of ice left in Hudson Bay, as the Canadian Ice Service map for 29 June 2016 (below) shows:
It seems to me that breakup for WHB this year is looking rather like 2014, which was something like a week later than the average since 1991, but time will tell. See below for comparison to 2009 (a late breakup year), 2015, and 2013 (lots of variability!), as well as a discussion of when bears come ashore in relation to this sea ice breakup benchmark.
Posted in Life History, Sea ice habitat
Tagged 30 percent coverage, breakup, Cherry, Churchill, early breakup, late breakup, onshore, polar bear, sea ice, Southern Hudson Bay, variability, western hudson bay
When you really want to challenge a speaker at a scientific meeting or public lecture, deciding what’s the best question to ask is often difficult. Here’s an example that might inspire you.
In 2009, I asked polar bear biologist Lily Peacock what appeared to be an innocuous question about Foxe Basin sea ice1 at a scientific workshop that got everyone’s attention.
The question — and the reaction — might surprise you.
Posted in Advocacy, Conservation Status, Sea ice habitat
Tagged Arctic marine mammals, breakup, Foxe Basin, global warming, Hudson Bay, International Polar Year, late breakup, Peacock, polar bear ecology, polar bears, public lectures, scientific meetings, sea ice, Society for Marine Mammalogy, spring sea ice, Stirling, workshop
In the last few days, ice coverage on Western Hudson Bay finally dropped below the 30% level that now defines ‘breakup’ for polar bears: a few bears near Churchill started to come ashore late last week but most will stay on the ice until the end of July. That means breakup this year was unofficially July 8th, a week later than average (July 1) for the third year in a row.
Don’t’ tell that to the folks at Polar Bears International, though, because they’re busy telling people that the ice-free season for Western Hudson Bay bears is now longer than it was before the 1990s. What they mean is that the overall trend is toward early breakup dates.
But what they don’t admit is that over the last 44 years, breakup was a full two weeks earlier than average for Western Hudson Bay only six times and only three of those early breakups occurred within the last 13 years. See the calculations below and see what you think.
Posted in Sea ice habitat
Tagged average breakup date, breakup, Canadian Ice Service, Churchill, early breakup, ice charts, Kelsey Eliasson, late breakup, Polar Bear Provincial Park, prolonged ice-free season, Seth Cherry, Wapusk National Park, western hudson bay