A group of specialists from the Severtsov Institute of Ecology and Evolution at the Russian Academy of Sciences have been tracking polar bears’ Arctic migration routes for over eight years now. In all, 20 animals in the Nenets Autonomous Area and on the Kamchatka, Chukotka and Yamal peninsulas have already received GPS collars, according to Rossiiskaya Gazeta.

Two female polar bears from Bely and Vilkitsky islands were the latest to get these tracking collars in the Yamal region. In fact, scientists tag females only, citing physiological factors. As male bears mature, their necks become wider than their heads, and GPS collars slip off in two or three months. Female bears’ necks and heads remain virtually the same size. Each GPS collar works for 18 months; after that, its buckle releases, and the tracker falls off without causing any problems for the animals.

Scientists were able to tag two more polar bears on the Yamal Peninsula. The devices allow them to watch the animals search for food and to track their routes in real time. These observations will eventually help researchers draw conclusions about Arctic climate change.

Before getting collared, both female bears were immobilised using a long-range injector because it is hard to anaesthetise animals that mostly roam the shoreline and that prefer to swim away at the first sign of trouble. A drowsy animal may drown, and it is very difficult to remove a 300-kg sleeping bear from the water. Therefore scientists prefer not to risk the animals’ life and health.

Experts took the female bears’ blood and fur samples for further tests that will make it possible to determine the amount of heavy metals and other pollutants inside their bodies and to evaluate their health. After waking up, the predators started acting normal.

“The devices send out one signal every four hours,” said Ilya Mordvintsev, deputy head of the Polar Bear Programme and a senior research associate with the Severtsov Institute of Ecology and Evolution. “By studying the routes of two female bears tagged on the Yamal Peninsula last year, we learned that they cover about 80-100 kilometres each month, mostly travelling along shorelines. They do not venture more than one or two kilometres inland,” he added.

Drifting sea-ice formations provide polar bears with ample food and shelter. Seals relaxing on ice-floes are their favourite meal. But ice formations continue to melt rapidly, receding further from the shoreline, and the sea remains ice-free for increasingly longer time periods.

“They [bears] eat dead animals that wash ashore, ransack bird nests and scavenge for leftovers at dumps and so on. The bears are unable to hunt in the water. Although polar bears try not to venture inland, hunger more often compels them to look for food anywhere they can,” Mordvintsev noted.

A 2018 Yamal Peninsula survey revealed that female polar bears and their cubs leave their coastal maternity dens earlier than planned and spend the summer months on drifting ice-floes in the high latitudes. Families with cubs that are 12 to 24 months old are often encountered on islands and along the shorelines, trying to subsist on scarce food. Lone bears aged two to three years are the most vulnerable because they are still young and inexperienced and unable to live and hunt on their own. Quite often, they are extremely malnourished and likely to perish; in fact, 10 percent of all bears roaming coastal areas tend to die.

After receiving GPS collar data, scientists can compare the routes taken by both female bears that were tagged this year, as well as those tagged on Shokalsky and Vilkitsky islands in 2018. Researchers will find out how long the polar bears stay on land, what islands they roam near in summer and other information. According to specialists, the Kara Sea’s polar bear population remains the least studied to date.

(Photo: © Ruslan Sleptsov)