© BJ Kirschhoffer/Polar Bears International
5/7/2020 5:55:38 PM
Bear Tracker Update Spring 2020
By Emily Ringer, Marketing and Communications Manager
For the last few months the polar bears of Hudson Bay have wandered a sea ice horizon deeply embedded in winter. Under hours of darkness and dancing ribbons of northern lights, they’ve followed their noses from one ice seal to the next. Now it’s spring in the Northern Hemisphere—days are growing longer and new life is taking shape across the Arctic.
Satellite imagery of sea ice concentration across the Arctic, courtesy of Universität Bremen.
Feasting on the sea ice
Put simply, springtime for Hudson Bay polar bears is a full-on feast. Seals in Hudson Bay have their pups in the spring, and young and naïve pups are an easy meal for a hungry polar bear. Blubber is an essential part of a polar bear’s diet, and the bodies of seal pups are approximately 50% fat, providing an excellent source of high-calorie goodness for the bears! Polar bears take advantage of this abundance and feast on ringed seal pups in the spring to store energy for times when prey is less available.
One of the main seal pupping regions is near the west coast of Hudson Bay. This year, many polar bears returned to this region during the spring for better hunting opportunities, even some bears that wandered far out into the middle of the bay in early winter. We certainly understand the logic—in areas where there are many seal pups, a polar bear can expend little energy but get a lot of food ... perhaps the equivalent to fast food for humans!
Love is in the Arctic air
Between April and late June adult male polar bears begin to find mates on the sea ice by following scented trails left by the female’s footpads. These trails appear to let the males know whether a female is in estrus.
Male polar bears will roam great distances across the sea ice in search of a mate. Scientists have observed that they generally choose one direction and follow it for days, altering their course only to investigate tracks that might have been left by a receptive female. If the tracks are promising, they’ll veer off in her direction and attempt to find her. If undisturbed by other males, a mating pair will stay together for about two weeks.
Female polar bears do not usually mate when they are still accompanied by cubs-of-the-year or yearlings, and we have a lot of active mama bears on our Bear Tracker right now! These bears are likely doing their best to avoid males and stay focused on keeping their cubs safe and their family fed.
Off the Tracker, den emergence
While the bears on the Tracker are enjoying the bounty of seal feasting season, new polar bear families have emerged from their maternity dens to make the trek to their sea ice hunting grounds. Families embark on these journeys when the cubs are strong enough to survive outside.
Polar bear cubs have fluffy fur designed to keep them warm in frigid Arctic temperatures, but they are vulnerable to hypothermia if they get wet. Out on the sea ice, mothers will walk long distances to find a path of solid ice rather than make their small cubs swim. For the next 2 - 2.5 years, new cubs will rely upon their mother for food, protection, and all lessons a young sea bear needs to learn in order to survive and thrive on top of the Arctic Ocean.
Updates on the Bear Tracker Bears
X33931 (Toledo Zoo, purple)
Toledo Zoo’s bear has traveled 3613 km (2245 mi) since being collared in September, still the second longest distance of all active bears on the Tracker right now. And the last few months have confirmed that she definitely has a preference for the southwest corner of Hudson Bay—she’s been circling and zigzagging here the entire time we’ve been following her. Polar bears are primarily out on the sea ice to hunt and feed on seals so we can only imagine she’s choosing to stay here because she’s having plenty of luck in this area. No need to wander and reinvent the wheel! Spring in the Arctic is also seal pupping season which is good news for this female bear and her single yearling cub. Seal pups, which are approximately 50% fat, are a high-yield snack for polar bears and an easy place for the cub to develop and hone its hunting skills! This is a critical period for this female and her yearling cub because they need to build up enough body fat to last them through the summer on land.
X32444 (Erlebnis Zoo Hannover, Hope, tan/gold)
Hope has traveled 2760 km (1715 mi) on the Tracker. Since we last checked in, she has broken free of her mid-bay circling and traveled north. Spring in the Arctic means seal pupping, and the west coast of Hudson Bay (off of Nunavut) is one of the main seal pupping regions. It’s likely that Hope chartered her course north in anticipation of this season of plenty. At seventeen years old, we imagine she’s discovered these hunting grounds before and knows that it will be a reliable source of food for her and her two yearling cubs. The cubs are no doubt carefully watching their mother’s movements, patterns, and behavior for tips on how to thrive in the Arctic. They need to learn the rhythms of life on the sea ice and this time of year is a prime opportunity to refine their own tracking, stalking, and hunting skills. We hope this family of three is finding success over fertile waters and getting fatter by the day!
X33928 (Munich Zoo, Tenya, dark blue)
Tenya has traveled 2385 km (1482 mi) since she was collared. After venturing near the coast in early March, she headed back out into the bay, nearly completing a full circuit of the lower left quadrant. We’re not too surprised that she chose this area—Western Hudson Bay is known to have many seals, and spring is seal pupping season. It’s also the peak of the polar bear’s hyperphagic period—a time of excessive appetite when polar bears try to fatten up on seals as quickly and efficiently as they can. Tenya is surely a hunting machine right now, and we hope her single yearling cub is taking good notes! There’s a lot to learn when it comes to catching seals, and the sea ice landscape and distribution of prey is a moving target. This is an important learning opportunity for Tenya’s cub and a really important time of year for their family. Hudson Bay melts in the summer so they need to build up enough body fat to sustain them for the upcoming four to five months on land.
X33110 (Rostock Zoo, Vilma, grey)
We’ll just go ahead and call her Vilma the Adventurer! Since being collared on the southern coast of Nunavut (further north than any other bear), she has traveled 5370 km (3337 mi)! This is still, by far, the longest journey of any active bear on the Tracker—nearly 1,800 km further than her fellow hunters. Vilma has a clear preference for the waters north of the Manitoba border, and it’s likely because this area is teaming with seals and their newborn pups. Notice how her path ventured deep into the bay in the dark of winter and then targeted this region with the turn of spring. Seal pupping season is a critical opportunity for Vilma to catch a lot of food for her family. It’s also a chance for her two yearling cubs to practice and hone their hunting skills on unassuming and easy prey. We hope these three are finding success and getting the meals they need to get them through the long summer fast on the shores of Hudson Bay.
X32491 (Tiergarten Schönbrunn, Hope Vienna, dark green)
Hope Vienna has travelled 2841 km (1765 mi) since being collared in September of 2019, and her path has certainly kept us on our toes! She ventured far, far north in the depths of winter and she is now our southernmost bear on the Tracker—floating on the sea ice in line with the border of Manitoba and Quebec. We hope that seal pupping season is proving to be bountiful in these waters for Hope Vienna and her two yearling cubs. After sixteen years navigating the sea ice, sniffing out seals, and likely birthing, raising, and weaning multiple cubs, we imagine she is a superb teacher. Surely her cubs have been watching her closely and even trying to hunt themselves. Young seal pups are an easy meal for a hungry adult polar bear and a manageable hunting endeavor for a polar bear cub on hunting training wheels. And seal pups are approximately 50% fat so they’re an excellent source of calories for polar bears preparing for a long summer fast on land.
X33401 (Canada Goose, Aurora, red)
Aurora has travelled 2468 km (1534 mi) since September, and she continues to set herself apart with a much straighter path than the classic zigzagging of other bears. And Aurora’s time and goals on the sea ice this spring have likely been different from these other bears because her cub is an entire year older than the other cubs. Cubs in this region stay with their mom for two to two and a half years so Aurora has/or is about to wean her cub and set it off on its own polar bear journey. Spring on the sea ice is also the mating season for polar bears, and with her cub now independent, Aurora is likely ready to mate again. And she doesn’t need to do any searching to make this happen! Male polar bears will seek out an available mate by following her scent left behind in her footprints. If Aurora does successfully mate this spring, the fertilized eggs will not implant until the following fall, and ONLY if she has enough fat to sustain herself and her cub(s) during the long denning season. This process is called delayed implantation. We hope Aurora has lots of luck fattening up so she’s healthy enough to bring a new cub(s) into the world next winter.
X19271 (Adventure Canada, Yuka, orange)
Yuka has walked, swam, and drifted 2639 km (1640 mi) since being collared, and she is farther north than any bear on the Tracker right now. Since we last checked in, she’s kept her movements fairly localized to the seas off of Nunavut. We imagine she traveled here in February and chose to circle here because it’s good hunting territory and the pickings are plentiful—especially during seal pupping season! Yuka is accompanied by a single yearling cub out on the sea ice. Her cub is probably taking advantage of seal pupping season as prime time to practice its most valuable skill, hunting! In preparation for striking out on its own, it must watch and help Yuka hunt thousands of times in a wide variety of circumstances. Polar bears can first give birth to cubs at five or six years old so at twenty years old, Yuka is surely an experienced mother and is imparting many valuable lessons to her cub. And the lesson for right now? Get as fat as you possibly can in preparation for the Hudson Bay sea ice melting and the summer’s fast on land.
X37054 (Shared Planet, Luna, pink)
Luna is still our easternmost bear on the Tracker, and she belongs to what scientists recognize as the Southern Hudson Bay polar bear population—which is evident when you compare her path and positioning to other bears in the bay. Luna has traveled 2372 km (1474 mi) since September, and in mid-March, she opened up her concentrated circling for wider waters. Even so, she has stayed fairly loyal to this corner of sea ice which we hope means she’s found fertile hunting grounds and some seal pupping territory. Luna is mother to two yearling cubs who are likely throwing their hats in the hunting ring at this point. Seal pups are accessible prey for young polar bears, and having been with Luna for about a year and a half, we can expect these cubs have absorbed much of her wisdom about how to track, stalk, and hunt seals. This seal pupping season of plenty is critical to Luna and her cubs. Hudson Bay melts in the summer so they need to build up enough body fat to sustain them for the upcoming four to five months on land.
Learn more about why scientists put tracking collars on polar bears, continue to follow the bears’ movements on the Bear Tracker, and check out our supplemental resources and games.