It’s summer in the Arctic, and the Hudson Bay polar bears are back on land.
Every year, Polar Bears International works with researchers to track select collared female polar bears from the Western (WH) and Southern (SH) Hudson Bay populations on our Bear Tracker. Following the bears on the sea ice via the Tracker is fascinating, as is watching their return to land during the summer melt period.
A good ice year—so far
This year, Hudson Bay experienced an unusual pattern of sea ice break-up. As part of the Seasonal Sea Ice Ecoregion, Hudson Bay annually freezes each winter and melts each summer. When the ice melts, the region’s polar bears are forced ashore, away from their seal prey. On average the sea ice break-up in Hudson Bay is three to four weeks earlier compared to the 1980s. But each year varies and, this summer, the ice in western Hudson Bay stuck around a bit longer. This translated into a few extra weeks for polar bears to hunt seals and, potentially, to gain many extra pounds. Extra body fat is critically important as these bears now face many months of fasting until the bay refreezes again in November or December.
While on land, away from their seal-hunting grounds, these polar bears must conserve as much body fat as possible. Polar bears have no true hibernation or metabolic changes that allow them to save energy during lean summer months, so they rest—a lot. They will find small amounts of calories when they can (e.g., eggs, berries, carrion), though terrestrial foods offer little energy compared to the bears’ normal blubber-filled diet. In fact, these bears lose up to ~0.9 kilograms per day when on land even while foraging. So, we can only hope that the bears return to land as fat as possible, especially those females who plan to give birth over the winter.
We’ve been following several polar bears who we expect to den and give birth over the winter. These pregnant bears came onshore in late July/early August and won’t see sea ice again until they leave their dens in March. That’s eight months without eating a decent meal, all while giving birth and nursing! Being obese now could help them make it until March with healthy cubs.
Sea ice minimum and fall freeze-up
As Hudson Bay polar bears find a good place to hunker down, stay safe, and rest through the next few months, we will take a short break on the Bear Tracker and keep our eye on sea ice conditions across the Arctic. The loss of July sea ice over the 44-year-satellite record is 68,500 square kilometers (26,400 square miles; an area larger than West Virginia) per year, or 7.2 percent per decade relative to the 1981 to 2010 average. The upcoming annual Arctic sea ice minimum (the lowest ice coverage of the year) occurs each September. When it is announced, we’ll update you on the amount of sea ice loss this year and what it means for polar bears.
Then, in October we will start following new polar bears on the Tracker as the bears gather along the coast to wait for freeze up and the polar bear migration begins. Polar Bears International will again be in Churchill to live stream and narrate the incredible activity and highlight our love of the bears. In the meantime, please check out ways you can join global efforts to support the species by checking out our new Advocacy Toolkit. See you this fall!
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