Wolverines are known as one of the most tenacious, fierce animals in the world and have defended themselves from bears before. However, in most situations, even a smaller bear, such as a black bear, would prove to outmatch the wolverine. The bear's size advantage is too significant.
Wolverines are solitary members of the weasel family and can grow to 40 pounds in weight. Armed with long, sharp claws, wolverines hunt small prey, such as rabbits and rodents. Larger prey, including caribou, are also targets for the wolverine. The wolverine's ability to fell animals much larger than itself is the biggest reason it would have a small chance in a fight with a bear.