Researchers See Signs of Chronic Stress in Polar Bears’ Blood

Since the 1980s, scientists have routinely helicoptered to the western edge of Manitoba’s Hudson Bay to find, immobilize, measure, and collect blood from polar bears to keep an eye on how they’re doing. What scientists are finding is worrying; climate change has driven sea ice to thaw sooner in the spring and freeze later in the fall, reducing the period when polar bears can hunt for seals—forcing them to fast far longer than normal.