Do lions create bad kamma for their next life when they kill? In Buddhism, bad Kamma begins with a bad intention. What can we say about animals, let's say a tiger or a lion that kills other living beings by instinct? They don't have the same understanding as we do as human beings and they simply cannot become vegetarians: so are they creating bad Kamma that might ripen in a next life? For instance, if I used to be a lion will I suffer bad Kamma consequences in this human life because I killed and ate living beings?
Bad Karma are caused by the three evil roots.


Lobha - Craving/Lust
Dosa - Aversion
Moha - Ignorance


Doing something bad without knowing it is bad falls under ignorance. Ignorance is there in all bad Karmas. But in the case of a lion killing a deer, it is stronger compared to a human killing a deer, given that he knows it is wrong. So the lion has strong ignorance on top of strong aversion and craving. That makes the Karma worse. One thing you have to understand about the law of Karma is that it is a law of the nature. It is not a god. So there's never a question of whether it is fair or not. Is it fair for children to get burnt if they touch fire without knowing it burns? Probably not! But the fire doesn't have a conscious to decide whom to burn or not to burn.