You might be wondering what infanticide is, infanticide involves the killing of a young offspring by an older animal of the same species. Infanticide can be committed by a female or a male.
Many animals commit infanticide such as dolphins, baboons, fish, insects but the most known for committing this crime is lions.
When male lions try take over a new territory they will oust the previous pride male lions and after succeeding at that, the next focus is to procreate and in order for that to happen, they will almost always kill the pride cubs, since they are not their own, they do not want to be the stepfathers to cubs who do not carry their own genes.
Lioness will also not be interested in mating when they are nursing young cubs, therefore the male lion would have to wait until the cubs no longer need to nurse before they can mate, thus killing the cubs enables the male lions to mate with the females immediately.
Lionesses will try to hide the cub or even go as far as leaving the pride to raise the cubs until they reach maturity, this is a very rare occurrence, because the males seem to always find the cubs.
Infanticide by lionesses even though its rare, it can occur, it is known as filial infanticide (when a parent kills its offspring), a lionesses will abandon her litter when only one cub is left, she will abandon her cub if it is too frail, disabled or suffering from an illness. Studies show that lionesses will increase their lifetime reproductive success by leaving single cubs and capitalizing in larger litters.
Infanticide is the most extreme conflict between lions, lionesses being the ones who suffer the most because they lose their offspring in which they already invested a lot of time and energy in.