3/16/2020 1:57:51 PM
Bear Tracker Update: March 2020
By Emily Ringer, Marketing and Communications Manager
The lives of polar bear families, like those shown on our Bear Tracker, are tied to Arctic sea ice—it is their home, dinner table, and in some areas, their nursery. It’s even written into their scientific name, Ursus maritimus (n): sea bear, ice bear, polar bear. From their sensitive nose, sharp teeth, and powerful jaws, to their curved claws, sticky feet, and double layer of fur, polar bears are supremely adapted for life on top of the Arctic Ocean. In fact, they’re classified as marine mammals!
Hudson Bay Polar Bears
During the winter months, sea ice expands in thickness and extent and polar bears across the circumpolar Arctic roam across the sea ice hunting seals. This is an especially important time of year for polar bears in seasonal sea ice eco-regions, like those shown on the Bear Tracker in the Hudson Bay.
In seasonal sea ice areas, sea ice completely melts in the summer and refreezes in the winter. That means that Hudson Bay polar bears spend an average of four to five months fasting on land each summer. While on land, they lose about 1 kilogram (2.2 pounds) of weight per day. The sea ice season is critical because it’s when they catch up on calories lost during the ice-free months!
Satellite imagery of sea ice concentration across the Arctic, courtesy of Universität Bremen.
While polar bears in this region have adapted to a fasting lifestyle, the concern is that, in a warming Arctic, the food-free period is getting longer. Human-caused climate change is warming the Arctic (and the planet) and causing sea ice to break up earlier in the summer and freeze up later in the fall. Western Hudson Bay polar bears are spending an average of three to four weeks longer on land than their grandparents did. Less sea ice means less feeding and more fasting—and in this region, we are already seeing the loss of sea ice habitat lead to population declines.
For now though, the bears are right where they like to be: hunting at sea, catching seals, and teaching their young the ways of the sea bear.
Moms and Cubs
Many of the bears on the Tracker began their journey in September with one or two COYs, or “Cubs of the Year.” Since our last update, these COY have all graduated to “yearlings”: that is, cubs between one and two years of age.
After these cubs and their moms emerged from their maternal dens in late March/April of 2019, they spent a few months on the sea ice before the ice began to melt and the bay broke up. COYs do almost no hunting in their first spring and summer on the sea ice. Instead, they follow closely behind their mothers, watching everything she does, and sniffing about curiously in the same places.
Now that these yearlings have a few more sea ice months under them, they’ve likely learned some tips and tricks and are starting to help their mother’s track, stalk, and hunt seals. After over a year of these cubs being completely dependent on their mothers, the extra hunting help is surely welcome!
A Polar Bear’s Path
Just as each snowflake is unique and one of a kind, so too is each polar bear’s path across the sea ice. Not only are polar bears choosing their own paths based on cues from their environment, but the platform beneath them is also constantly shifting and moving. Sea ice is a dynamic habitat and can drift great distances in a single day, pushed by wind and ocean currents.
As we turn the corner into spring, it will be interesting to see how the bear’s choices and patterns may change. Polar bears respond to seasonal fluctuations and the distribution of seals, and spring in the Arctic means seal pupping season. This is a critical opportunity for bears to feast, fatten up, and prepare for the long fast ahead, so we expect to see bears setting their course for food-rich areas in the bay.
While we make educated predictions based on what we know about polar bear behavior and the Hudson Bay ecosystem, each polar bear is truly unique, and we don’t know the details of what spurs them to make the choices that they make. It’s something researchers are very interested in—especially as Arctic sea ice continues to decline. For more information on tracking polar bears please visit our website, continue to follow the bears’ movements on the Bear Tracker, and check out our supplemental resources and games to engage your viewership in polar bear conservation.
Collared Bear Updates:
X33931 (Toledo Zoo, purple)
This female bear has traveled 2632 km (1635 mi) since she was collared—the second longest distance of all active bears on the Tracker right now. Since setting off from the tip of Wapusk National Park, she’s been zigzagging across the southwest corner of Hudson Bay, in an area known to have lots of seals. And as she’s remained in this region, we can assume she’s having some success hunting! She is accompanied by one yearling cub, who graduated from being a COY, or “Cub of the Year” in January. This is her cub’s second time out on the sea ice but first full-length season. Her cub was likely born in a maternal den around January of 2019 and spent that spring out on the sea ice with mom before coming ashore as the sea ice broke up in the summer. Now this cub is getting the complete sea ice season experience, and no doubt mother bear is carefully teaching it the ins and outs of thriving in the Arctic. And lucky for mother bear, her cub is probably starting to contribute to the tracking, stalking, and hunting of seals!
X32444 (Erlebnis Zoo Hannover, Hope, tan/gold)
Seventeen-year-old Hope has traveled 1851 km (1150 mi) since she was collared in September. After a few weeks of keeping to the sea ice that hugged the shore just off of Wapusk National Park, she struck out deeper into the bay and is now embedded in the sea ice landscape far from shore. This area must be a suitable hunting ground as she is now slowly circling in one region, back and forth across the border between Manitoba and Nunavut. And finding successful hunting grounds is extra important because she has additional mouths to feed! Hope is mother to two yearling cubs (recent COY, or Cub of the Year graduates), and this is their first complete season out on the sea ice. They are likely just starting to help Hope hunt, and they will stay by her side for about one more year. In preparation for striking out on their own, they must watch and help their mom hunt thousands of times in a wide variety of circumstances. And after seventeen years navigating the sea ice, sniffing out seals, and likely birthing, raising, and weaning multiple cubs, Hope is probably a superb teacher.
X33928 (Munich Zoo, Tenya, dark blue)
Tenya has traveled 1610 km (1000 mi) since she was collared. She is our southernmost bear on the Tracker right now, and she has really seen the sea ice sights to get here! So far, she’s chosen a sweeping circular path, covering a diverse sampling of what Hudson Bay has to offer. Tenya hugged the coastal waters off the shoreline for a bit, then ventured north into the waters off of Nunavut and into the middle of the bay. Come January, she turned her nose south and began zigzagging her way back towards the coast of Manitoba. The western part of Hudson Bay is known to have a lot of seals, and it’s possible that Tenya chose to return to this region in anticipation of seal pupping season in the spring. Tenya is making this journey with one yearling cub (who recently graduated from COY status). Her cub was probably born in January of 2019, so this is its first full season out on the frozen ocean. Tenya’s cub is certainly getting an all-star tour of its sea ice home, and likely starting to help mom in the hunting process!
X33110 (Rostock Zoo, Vilma, grey)
Fourteen-year-old Vilma has embarked on one of the more adventurous paths on the Tracker. Since being collared on the southern coast of Nunavut (further north than any other bear), she has travelled 4501 km (2797 mi)! This is by far the longest journey of any active bear on the Tracker right now—Vilma has traveled twice as far as most of the other collared bears. Vilma zigzags across the sea ice with two yearling cubs close behind (since our last update her cubs had their first birthday, so they’re no longer considered COYs, or “Cubs of the Year.”) Her cubs spent a few months on the sea ice after emerging from their den in late March/April of 2019, but this is their first full season out on the sea ice. Initially, cubs don’t help much with hunting. They must learn to be quiet so their mother can catch a seal—and then they learn how to hunt by watching her. By now though, we can expect that these cubs have absorbed enough of their mother’s wisdom to chip in and help track, stalk, and hunt seals! As the deep winter starts to lift, we look forward to watching the route Vilma selects for her family. So far, she’s really kept us on our toes!
X32491 (Tiergarten Schönbrunn, Hope Vienna, dark green)
Since being collared in September, Hope Vienna has travelled 2052 km (1275 mi). She began her journey close to shore before making large sweeping movements deep into the bay. She traveled far north—floating centrally in the waters between Nunavut and northern Quebec—before curving her path and venturing back in the direction she came from. Hope Vienna traverses the sea ice with two yearling cubs in tow. Cubs in this region are born on land, but home for polar bears is on the sea ice, where they hunt seals at open leads. Polar bears can first give birth to cubs at five or six years old so at sixteen years old, Hope Vienna is likely an experienced mother. Throughout the winter she’s been skillfully showing her young the ropes of hunting seals, swimming, travelling the sea ice, and thriving in the Arctic. And with any luck, these yearlings are now starting to pull their own weight and helping their mother hunt! As winter opens into spring, it will be interesting to watch the route and region Hope Vienna chooses for her young family.
X33401 (Canada Goose, Aurora, red)
Aurora has walked, swam, and drifted 1921 km (1193 mi) on the tracker thus far. Her route tends to zigzag less than other bears, with long straight-ish paths spanning ¾ the width of the Hudson Bay! After venturing deep into the waters off the coast of northern Quebec, she took a 180 degree turn in January and headed back towards the sea ice above Manitoba. The western part of Hudson Bay is known to have a lot of seals so it’s possible Aurora adjusted her path in anticipation of seal pupping season in the spring. Aurora is accompanied by one cub out on the sea ice! At ten years old, this is likely her second or third time with a cub. And given that this cub is between two and two and a half years old, we expect they are working and hunting as a mother and cub team—which must be a bit of a relief for Aurora! Most cubs in this region stay with their mom for two/two-and-a-half years so we can expect that Aurora is imparting her final sea bear lessons on her cub and that she will wean and set her cub off as an independent polar bear sometime this spring.
X19271 (Adventure Canada, Yuka, orange)
Yuka has traveled 1838 km (1142 mi) since being collared, and it’s been really interesting to watch her path! She is our northernmost bear on the Tracker, and it looks like she has an affinity for the Far North sea ice off Nunavut. We imagine she is lingering here because she’s found a suitable stretch of sea ice for hunting seals—which is critical for her and her offspring! Yuka has one yearling cub, born in a maternity den around January of 2019. This may be her cubs first full season on the sea ice, but chances are it’s starting to contribute to the hunting efforts! Yearlings are generally fairly helpful hunters because they’ve carefully observed their mother’s movements and methods for over a year. Nonetheless, there is still much to learn! Yuka’s cub will stay with her for another year or so refining its hunting, feeding, and swimming skills so that it may survive in the Arctic. And lucky for this cub, at twenty years old, Yuka is surely an experienced mother and an efficient teacher.
X37054 (Shared Planet, Luna, pink)
Luna is our easternmost bear on the Tracker right now, and she belongs to what scientists recognize as the Southern Hudson Bay polar bear population—which she makes quite clear through the path she’s chosen out on the sea ice! Luna has traveled 1611 km (1001 mi) since being collared, and for the last month she’s been zigzagging repeatedly across one circle of sea ice. In fact, her recent movements are so concentrated that her overlapping paths are starting to look like a little pink blob on the map. She must have found some fairly fertile hunting grounds! Luna is roaming the sea ice with two yearling cubs close behind. Her cubs were born in a maternity den around January of 2019, so they’ve been observing and learning from Luna for over a year now. At this stage, we expect her cubs are starting to gain increasing confidence out on the frozen ocean and helping Luna with some of the hunting. As winter fades into spring, we’re keeping a curious eye on Luna’s route finding. Will she change course come seal pupping season? Only time and some more GPS data points will tell!