Why are the Cape/African lion the only cats that live in groups?
I would think it’s because they live in plains and savannahs rather than inside the jungle like all other big cats. This sort of territory is a lot more dangerous, and also serves as hunting ground for most predators. Tigers and leopards only exit the jungle to hunt, so anything living in there has to protect themselves with cooperation, unless it’s a big animal like a rhino, and even elephants remain in groups. While the jungle is dangerous too, it’s more closed and easier for its inhabitants to get along by themselves, but even then, many animals in it still live in groups, and I believe that tigers do for a while, albeit much smaller groups. Could be wrong though, don’t quote me.