By Margaret Archibald
It can be difficult to see something you aren’t expecting to see. Especially if you have never seen it before. On May 18, 2018, Walrus Island State Game Sanctuary manager Ryan M got back to our research cabin from the Steller sea lion viewpoints at the south end of Round Island and told me that there were two young walruses hauled out there with the sea lions. When you live on a one mile wide island exciting is exciting, and we had never seen a walrus actually haul out in the sea lion turf before, so we geared back up, and headed back out- this time with the “big” camera to get better pictures. As we hiked Ryan told me it had been a smallish 7 or 8 year old walrus accompanied by a (very young for this area) 2 year old calf. He kept gushing about what beautiful tusks the bigger one had and we hurried up the rocky trail not wanting to miss our opportunity to snap some epic photos of the “interaction” of these two species of huge pinnipeds; Pacific walruses and Steller sea lions. When we got to East Cape, the two walruses were still there, napping on the ledges surrounded by somewhat nervous sea lions, who were also resting but keeping a safe distance. When we got to the viewpoint above the ledges we saw that the bigger of the two walruses had rolled over, and we immediately noticed what Ryan had previously missed! The bigger “young” walrus had no penile opening! it was not a young male, it was an adult female walrus! and the calf was not lost- it was with its mother! Why was this so exciting? Why were we not expecting to see them there? Neither of us had never seen a female walrus before! Female pacific walruses do not typically come down to Bristol Bay in summer. Until recently, biologists believed that female Pacific walruses prefer not to stray far from the edge of the pack ice and only do so occasionally, or when necessary during migration.
For all Pacific Walruses, the preferred winter habitat is the zone where thick multi-year pack ice meets the liquid ocean. In a normal walrus year, all the walruses would spend the winter at the edge of the ice pack. The females would have followed it south from the frozen arctic into the Bering Strait as the polar ice cap extended south in the early winter. Traditionally in the spring, at the end of an exhausting fighting and mating season, but before the pups of the previous year are born (walruses gestate for 15 months) the eastern population of pacific walruses (most of the Alaskan population) begin their annual migration. In this case the female walrus and their young stay with the (now receding northward) edge of the ice pack where those who will calve can safely do-so on the floating ice, and those still nursing their hungry ~400 pound yearlings can easily slip from the ice into the water to feed from the productive continental shelf directly below. Typically many of the adult male walruses in the eastern population have opted to migrate south into the productive Bering sea and Bristol Bay where there is plenty to eat and warm sunny beaches to help them molt and recover from the winters fasting and fighting.
Over the last decade the arctic has experienced warmer and warmer summers causing much of the multi-year sea ice and the densest parts of the ice pack, to melt. Each winter new ice forms but first year ice melts faster the following spring and the essential floating habitat it provides for the walrus retreats further each summer into the Arctic ocean, off the continental shelf and far from their traditional feeding areas in the relatively shallow Bering and Chukchi Seas. Starting around the summer of 2007 when the beginning of an El Niño cycle contributed to warmer than usual sea surface temperatures and less than usual sea ice, female and young walruses began hauling out on sandy beaches along the arctic coasts of Alaska. Although this seems like a great adaptation to changing climate conditions beaches have a couple big drawbacks over sea ice when it comes to rearing young. Beaches do not drift, so if you are a walrus mother hauling out at a terrestrial haul out, once you have eaten all the nearby clams you will not drift over fresh clam beds. instead you will have to swim farther to find nutritious food, and take your vulnerable young calf with you, or look for a new beach. The long swims and long hikes up the beach add stress and energy expenditure to the mothers and calves during this critical time of growth. Hauling out on beaches also exposes the walruses to landlocked summer polar bears and the potential for smaller calves to be crushed in stampedes to reach the safety of the sea in the event of a disturbance.
This uncomfortable fact about walrus lifestyle has portentous implications for the future of the species. The traditional way of life for Pacific walruses in the Chukchi Sea and eastern Bering Sea may have come to an end with the multi-year sea ice now regularly receding beyond the edges of the continental shelf in the Arctic. In the future only walruses capable of adapting to new environmental conditions, may survive.
So maybe our Ms walrus, was a frontierswoman, a pioneer looking for a safe place to raise her calf. Maybe she came to Bristol Bay to try the clams and see if it would be a nice place to for them to spend summers, beyond the range of hungry polar bears. Maybe not finding the same type of sea ice that she was raised on for her young calf, she followed the clam beds down the coast thinking only about their full bellies. Needless to say, to us, she arrived like a messenger, bringing a tale of changing conditions in the north and perhaps an omen that these remarkable mammals may have what it takes to modify their traditional range and migrations and adapt to a warmer future in the arctic.
Sources cited:
Jay CV, Fischbach AS, Kochnev AA.2012. Walrus areas of use in the Chukchi Sea during sparse sea ice cover. MARINE ECOLOGY PROGRESS SERIES. Vol. 468: 1–13, 2012 doi: 10.3354/meps10057
Demer L. 2017. Walruses adapt to loss of sea ice and are not endangered, feds say. Anchorage Daily News. October 4, 201
Fay, F. H. 1982. Ecology and biology of the Pacific walrus, Odobenus rosmarus divergens
Illiger. US Fish and Wildlife Service, North American Fauna No. 74, Washington, D.C.
US Fish and Wildlife Service. 2017. Walrus and the Endangered Species Act. www.fws.gov/alaska/fisheries/mmm/walrus/esa.htm
US Fish and Wildlife Service. 2017.Frequently Asked Questions The Pacific Walrus Haulout Near Point Lay, Alaska. www.fws.gov/alaska/fisheries/mmm/walrus/pdf/Point%20Lay%20Walrus%20Haulout%20FAQs.pdf
North Slope Borough website. 2014. Walrus Haul out events on the North Slope. http://www.north-slope.org/departments/wildlife-management/studies-and-research-projects/walrus/walrus-haulout-events
