Buzz
What was once an uncommon sight—a bear roaming outside its den before spring—has now become more frequent, all due to climate change. According to The New York Times, warmer temperatures are causing American black bears to wake up earlier than usual, and in some cases, preventing them from entering hibernation altogether.
Hibernation plays a crucial role in the black bear's life cycle. While awake, a bear must consume between 11 to 18 pounds of food daily to maintain a healthy weight. By hibernating, the bear can survive the food scarcity that typically occurs during the colder months.
However, as climate change causes extreme weather events in the western U.S., black bears in that region are starting to behave differently. For instance, last year, the Pine Nut Mountains in Nevada experienced an unusually heavy snowfall, resulting in a large pine nut crop. This winter, snowfall levels were near record lows, leaving pine nuts on the ground for longer periods. The extended food availability caused some bears to either delay hibernation or skip it entirely.
Many of the bears that eventually found their way into their dens this year were awakened earlier than usual. A 2017 study found that for every 1°C rise in minimum winter temperatures, bears hibernate for six fewer days. In January 2018, temperatures in the Pine Nut Mountains were 5.4°C higher than the region's 20th-century average.
In some years, bears wake from hibernation during droughts, which are worsened by climate change, making food scarce. When this happens, bears may end up on private property, scavenging through trash cans and bird feeders, or sometimes even breaking into homes. Fatal bear attacks on humans aren't common, but the more frequent outcome is that the problem bear is euthanized. Bear management groups often try methods like capture and release or aversive conditioning before resorting to this, but still, dozens of bears are euthanized annually by states.
Black bears aren't the only bears having to adapt to global warming. In the Arctic, polar bears are losing the sea ice they rely on to hunt marine mammals and are increasingly moving onto land in search of food. Climate change is driving both species of bears closer to human-populated areas, which will likely lead to more conflicts between bears and humans in the future.
