Sloth bears seem oblivious to lurking tigers, but when attacked, they often fight back more effectively than their foes.
In North America, adult bears rarely have to fight off predators to protect their lives. However, the situation is quite different for sloth bears on the Indian subcontinent. They frequently confront one of the fiercest predators, the tiger. Although these big cats are formidable, sloth bears, roughly the size of a small black bear, are not easy prey for them. A study published in the journal Ecology and Evolution in July revealed that tigers in Indian national parks can easily ambush sloth bears. The bears do not seem to be aware that they are at risk of becoming a tiger’s meal. However, once a tiger attacks, sloth bears often succeed in driving their adversary away.
A sloth bear confronts a nearby tiger. (Photo: Dicky Singh).
Researchers hope that this new finding may provide insights into measures to reduce conflicts between humans and sloth bears, a species classified as vulnerable. Sloth bears are not predators; they primarily feed on termites, ants, and fruits. However, they have a reputation for being aggressive towards people who share their habitat. Numerous reports indicate that they are responsible for more human attacks than any other large predator in the world.
Thomas Sharp, a wildlife ecologist at Wildlife SOS, a conservation organization in India and author of the study, asked local residents why sloth bears are so aggressive since he began studying them two decades ago. “The answer I always received from people was that they fight with tigers,” Sharp stated. Consequently, he collaborated with colleagues to better understand the interactions between sloth bears and tigers. They reviewed 40 videos and three photo sets from safari-goers in Indian national parks capturing tigers hunting for sloth bears.
Sloth bears spend a lot of time foraging and often keep their heads low while searching for insects. They make a lot of noise and lack high alertness, Sharp noted. Tigers, on the other hand, are known for their stealth. This combination means that bears are more vulnerable to ambush. Tourists often observe tigers getting very close—within three meters—before sloth bears realize they are in danger. However, once aware of the threat, sloth bears are ready to fight back. They rise up on their hind legs and either strike or chase the tiger away. They also emit a growl reminiscent of a barking dog. This aggressive strategy proves effective, as approximately 86% of sloth bears escape unharmed.
In one of Sharp’s favorite videos, a tiger sneaks in close enough to attack the sloth bear from behind. When the bear turns around, the tiger retreats with its ears back, resembling a timid house cat rather than a fierce predator. Although sloth bears may not enjoy fighting, they and tigers coexist in open forest areas, making escape and concealment challenging.
Human attacks typically occur when sloth bears are startled at close range, similar to the behavior observed with tigers in the study. Sloth bears also often stand upright, swat, and chase in a similar manner. According to Sharp, sloth bears may have developed a strong aversion to unexpected attacks from tigers or other predators in the past. He mentioned that he plans to continue collecting new videos of interactions between sloth bears and tigers each year.
