Adult polar bears in Norway have been getting fatter and healthier even as the sea ice around them keeps shrinking. That pattern challenges the easy assumption that less ice always means thinner bears, at least for some Arctic coastlines.<\/p>\n
Records from Svalbard<\/p>\n
Long-term capture records in Svalbard, a Norwegian island chain far north of Norway<\/a>, tracked 1,188 spring measurements from 770 adult bears. Over decades, the Norwegian Polar Institute (NPI<\/a>) ran spring captures that built this measurement archive. Using that archive, Jon Aars, a population geneticist, found bears grew heavier after 2000.<\/p>\n Meanwhile, sea ice kept shrinking during those years, so the trend forced a closer look at how bears found food.<\/p>\n Ice-free season lengthened<\/p>\n Along the Barents Sea<\/a>, north of Norway and Russia, sea ice vanished while the climate warmed about 3.6 degrees Fahrenheit per decade. Fewer months of solid ice shortened the main hunting season, leaving bears to burn stored fat for longer.<\/p>\n Across the 27-year record from 1992 to 2019, the number of ice-free days climbed by about 100 days total. With ice habitat disappearing more than twice as fast as in other regions, scientists expected leaner bears whenever ice was scarce.<\/p>\n Fat stores matter<\/p>\n Polar bears, Ursus maritimus, live in 20 recognized populations<\/a> that depend on sea ice to reach seals. Spring hunting let each bear build fat reserves, stored energy that later powered it through long weeks ashore.<\/p>\n Wildlife biologists watch body condition, a quick read on nutrition, because it often changes before cubs or survival rates fall. Better weight alone still cannot prove the population is safe, since fewer cubs could arrive even when adults look strong.<\/p>\n New foods appear<\/p>\n Onshore feeding became more common once ice started disappearing<\/a> for longer stretches, especially during the summer months. News coverage linked that change to animals picking up food on land and scavenging carcasses.<\/p>\n \u201cIn this area, bears have access to reindeer and eggs on land, walrus carcasses, as well as seals,\u201d said Aars. That menu depended on local prey and scavenging, and it could vanish if those choices became scarce.<\/p>\n Summer on shore<\/p>\n By summer, more bears spent extended time on land as the sea ice retreated away from the islands. Once ashore, they searched beaches, open ground, and bird cliffs for quick meals when the usual marine hunting slowed.<\/p>\n NPI teams previously recorded nest raids in western Svalbard, and tracking data later showed more females lingering near bird colonies. Seasonal nest food offered a boost for some individuals, but it also stayed patchy and could not feed everyone.<\/p>\n Two travel styles<\/p>\n