Blubber. Blubber. And more blubber! Spring is the best time to be a hungry polar bear, and—as the bears on our Bear Tracker show—it’s the season when hunting is good and calories are abundant.
We are now in late May, which means that polar bears from the Western and Southern Hudson Bay populations have been on the sea ice for about six months. Though they’ve been actively hunting all that time, it’s only in the last six to eight weeks or so that food has truly become plentiful, allowing the bears to finally gain some serious weight. Seals in Hudson Bay gave birth recently and by now these pups are chubby enough to constitute a satisfyingly blubbery meal yet still naive enough to be easy prey. Polar bears of all ages are out on the sea ice, consuming as many as these little fat nuggets as possible while they can.
This period is called “hyperphagia”—basically, eating as much as possible when possible. Polar bears can eat over 100 pounds of blubber in a single sitting, and they have a very effective rate of converting the blubber they eat to fat they store on their bodies (much more efficient than humans, luckily for us!). After stripping a seal of blubber, polar bears may even leave the meat behind for scavengers and instead focus on finding the next blubbery meal. This is why some scientists like to call polar bears “lipovores” instead of “carnivores”—-these bears prefer to eat the more caloric blubber over protein-rich meat when they have a choice.
In June or July, the sea ice in Hudson Bay will start to break up and polar bears will be on shore again for about four to five months without access to their seal prey until the ice refreezes. Polar bears lose about one kilogram per day during this time, so every kilogram gained today matters in the long run.
Spring is a busy season. While most bears only need to focus on feeding themselves, moms with young cubs are now teaching their cubs how to find food and hunt. Two-year-old cubs are being weaned and will be on their own soon, if not already. Newly single females will be looking to mate, and adult males will be on the prowl, literally, to find a receptive female on the vast sea ice landscape.
Hunting, traveling, and mating all rely on the presence of sea ice, with polar bears using their noses to find each other and seek out food all while navigating the ice shifting beneath their paws. This gets even more difficult as the polar bears’ habitat melts beneath them. Cubs are learning lessons now that might not be applicable by the time they’re adults, and adults are adjusting constantly to a world that makes less sense.
The key to protecting Arctic sea ice is society moving toward sustainable energy and embracing community solutions to lower carbon emissions. Protecting sea ice means protecting polar bears, people, and our planet. Check out our new Advocacy Toolkit for ways you can help us keep polar bears roaming the Arctic for generations to come.
Sponsored Bear Updates
1. Tiergarten Schönbrunn, Erlebnis Zoo Hannover, Rostock Zoo, Tierpark Hellabrunn, CERZA Parc Zoologique Lisieux: X33872, Arctic Ambassador
Arctic Ambassador Bear is still sticking to her favorite region! She is still not the farthest mover, having traveled “only” about 892 km by mid-May. She has been hanging around a particular region of central Hudson Bay for many weeks at this point, so we can assume there is great seal hunting there! Her two yearlings are hopefully helping her hunt and getting fat fast, packing in the calories while ice is still available and seals are accessible. This 15-year-old Southern Hudson Bay (SH) female should still have over a month of hunting left, and often sea ice will linger along the Ontario coast giving SH bears a few extra weeks to hunt. We will watch where Arctic Ambassador Bear moves and comes onshore over the summer; until then we wish this family happy hunting!
2. X37037: Canada Goose, Aurora 2
Aurora 2 is likely having an eventful spring. Her cubs are now 2.5 which means that they will be weaned and set loose on their own sometime this spring, if not already. This 20-year-old will then balance hunting seals with being wooed. No doubt a male (or two) will sniff her out on the sea ice and attempt to mate, staying with her for a week or two while fending off other males. To ensure a pregnancy, Aurora 2 will need to pack on potentially hundreds of pounds. Once back on land this summer, she won’t eat again until about March 2023; the body fat she carries as of July is what she will have to live off of while giving birth to and nursing cubs all winter. Aurora 2 must balance her energy expenditure carefully, consuming plenty of seals while minimizing travel. She’s a big walker, having already moved over 1,463 km this year. Though now she is very slowly zigzagging northward farther into Hudson Bay, we know she’ll be back on shore in the next month or so. Until then, happy hunting (and mating)!
3. Explore.org: X33714, Daphne
Daphne remains a true Western Hudson Bay polar bear. This 11-year-old mom of one yearling has progressively made her way closer to the Nunavut coast over the last month. We know she’s not heading to land, but instead going to hunt! This is a known region of seal pupping, evidenced further by two other bears in close proximity to Daphne right now on the Bear Tracker. Daphne knows this area well and, now that she has her yearling to help, we hope she is getting plenty to eat. She should have at least one more month of hunting to go, and no doubt she will travel plenty during that time. She has already covered over 1,803 km since last fall, not too shabby. Happy hunting to Daphne and her cub, maybe we will see them around Churchill this summer!
4. Frontiers North Adventures: X33505, Floe
Floe is single and ready to mingle! She will have recently weaned her cub this spring and is likely looking to mate again. Males will be sniffing her out on the sea ice, but Floe has even more immediate needs: blubber. Floe is now 15 and well-versed in where and when to find seals; she’s currently in a known region of good seal pupping and hopefully filling up on food fast. She will need to gain lots of pounds to sustain a pregnancy through the summer, fall, and into next spring without eating. She has already walked over 1746 km this year, zigzagging exclusively in the western region of Hudson Bay. She knows this area well, and it will be interesting to see where and when she comes back onto land this summer. Good luck to Floe!
6. Natural Exposures: X33896, Portia
One of our biggest movers of the year at 2,084 km already, Portia is still on the move yet has a relatively small home range–she likes zigzagging! She will have recently weaned her cub and is likely ready to mate again. While males sniff her out on the sea ice, Portia will be focused on finding seals and consuming as much blubber as possible: she needs to pack on plenty of pounds this spring in order to sustain a pregnancy through the summer and fall. If she gets pregnant, she will enter a den this fall and not emerge again until about March 2023. That’s up to 8 months without eating! At 13, Portia knows enough about hunting, navigating, and being a mom so hopefully she can get as fat as possible over the next month before she returns to shore. Happy hunting, Portia!
