Much of what we know about polar bears is the result of research conducted in the Churchill area. As part of a long-term study with over forty years of continuous data, the Canadian Wildlife Service captures and studies bears along western Hudson Bay. They have most recently complete a three year mark recapture study indicating a marked decline in the western Hudson Bay population.
As part of this study, researchers locate polar bears from the air, travelling by helicopter along the coast of Hudson Bay, generally within the boundaries of Wapusk National Park. Once a polar bear is spotted, researchers assess the location and the potential risk to the bear; provided that the bear is not close to water or another bear, the helicopter approaches. The vast majority of bears will try to get away; a few, however, have been known to turn and even take a swipe at the incoming researchers.
The pilot then attempts to position the helicopter almost directly above the bear. Researchers load a dart with Telazol – the drug used to immobilize bears – and try to place the dart in a spot between the neck and shoulders. This is one of the few spots on a polar bear where the fat layer is thin and the drug will be released directly into muscle. Once in the muscle it will circulate much more quickly than it would through fat tissue.
Once darted, the bear will stagger and stop, eventually sitting and then lying down. Once its head and neck are relaxed, the researchers land and approach. The bear is then placed in what is called a ‘sternal recumbent position’, which is simply lying on its stomach with all four legs spread out. This position places the least strain on the bear while the researchers are working.
After heart rate, breathing and body temperature have been recorded, the bear is checked for identifying tattoos and ear tags. Previously handled bears will have a tattoo on the inside of its lip and little white ear tags. Existing tattoos or ear tags are referred to the researcher’s fieldbook in which all handled bear’s histories are recorded. If the bear has not been handled before, it is recorded and given a unique number as well as an ear tag and tattoo.
Each polar bear throughout the world has a code, such as X4040. Sometimes referred to as the ‘x-files’, all bears originally tagged in Canada begin with the letter X. Measurements of length, girth, head length and head width are taken to determine the overall health of the polar bear.
Researchers will also pull a tooth to determine the age of the bear. The tooth is one of the small premolar teeth right behind the canines, for which there is no known use. Back at the lab, the tooth is sectioned and the lines are counted, similar to counting rings on a tree. In polar bears, each line represents one year of age.
Finally, a small circle of dye is put on the back of each animal in order that it is not captured in the same season. This mark lasts four to five weeks and some bears still sport this mark during Churchill’s bear season. After marking the bear, researchers ensure that there are no threatening bears in the area while their bear regains consciousness before boarding the helicopter to head off in search of another ‘x-file’.