Climate change and global temperature rises are impacting the food availability and hibernation cycles of bear populations around the world, threatening the survival of bear species, including the Asiatic black bear.
Our Earth is heating up at an unprecedented rate. Climate change is leading to a cascade of changes in animal and plant habitats all across the globe, but its impact on bears, including the Asiatic black bear, is particularly significant. This is especially true regarding the bears’ wintering behaviours and, as a direct result, is leading to an increased chance of human-bear conflict and threatening its survival of the species.
Like their black and brown bear cousins of North America, Asiatic black bears have evolved in synergy with their natural habitats’ climate and food availability. These mammals are hardwired to exploit seasons of food abundance to survive other seasons of food scarcity, entering hibernation where winter food availability is scarce and winter denning is necessary for bear survival.
These circannual activity rhythms have a predictable effect on bear behaviour over the course of a year. Even at Animal Asia’s bear rescue centre in the foothills of Tam Dao National Park Vietnam, the bears’ hunger drives, caloric needs, and food preferences generally mirror wild observations. In late spring and summer, there is a gradual increase in appetite, peaking roughly mid-autumn (this period of gorging is known as hyperphagia). In winter, hunger drives begin to wane before gradually dropping to their lowest levels in spring, when the annual cycle starts again. Around one in every five of rescued bears chooses to hibernate through winter.
In autumn, to prepare for winter scarcity, bears will seek out and indulge in high-calorie foods to add fat reserves. One of the most important autumn food sources for bears is hard mast – acorns and beechnuts. Recent research carried out in Asiatic black bear habitats in Japan and Pakistan suggests climate change is likely reducing the coverage of both oak and beech forests, subsequently leading to a reduction in a critical autumn food source for bears. Without the autumnal glut of hard mast to feast on, bears may be unable to store enough fat reserves to sustain themselves through winter.
Other research has shown that warmer temperatures have led North American black bears and brown bears entering their dens later as well as leaving them earlier than expected. In fact, for brown bears, every increase of 4°C sees bears leave their dens ten days early. For black bears, increases of just 1°C reduce hibernation by an average of six days. It has been hypothesised that by 2050, North American black bear hibernation could decline by 15 to 39 days. Bears will be waking early and leaving their dens to search for food during a time of year when much of their foraging grounds have yet to spring to life. Simply put, bears are responding to increasing temperatures much quicker than much of the plant and animal life that sustains them.
It’s not only hibernation behaviours that are being impacted by climate change. Recent research into wild Asiatic black bear populations from the Hindu Kush Himalayan region and Iran predicts that warming temperatures will see bears migrate to higher elevations At the same time, longer periods of warm weather will increase bear activity across the year. New higher-altitude environments may fail to provide new and active bear populations with enough food and other resources for survival.
Malnutrition and starving bears are of obvious concern here. Equally worrying is that bears with inadequate natural food sources are more likely to wander into human communities to forage. As human populations expand and encroach on dwindling wild bear habitats, the interface between human settlements and bear territory is increasing. Combined, all of these factors increase the chances of human-bear conflict.
While, of course, dangerous for humans, human-bear conflict is more often fatal for bears. In Asia, bears have been known to forage farming crops and predate on livestock, which can result in local farming communities retaliating with lethal force. Human-bear conflicts often result in bear deaths in countries without humane management options in place, such as the live relocation of “problem” wildlife. This puts yet more pressure on already vulnerable populations of wild bears.
The consequences of climate change are impacting our shared planet in myriad ways. As a global community, we are standing at the edge of a precipice. The onus is on each of us, as individuals, communities, or governments, to act. The influence of warming global temperatures on bears is unmistakable. Yet, the effects on countless other species across our shared planet are still unknown. We risk any number of ecological tipping points resulting in the mass extinction of species, reminding us yet again that the climate crisis is a biodiversity and wildlife crisis too.
This story is written by Heidi Quine, Vietnam Bear and Vet Team Director, Animals Asia.
Featured image courtesy of Animals Asia.