Why do (male) cats kill the kittens after they are born?

As others have said in their answers - some male cats may kill kittens to induce the female to come into heat, or to reduce potential competition in their territory. These are behaviors humans have noticed in some animal species, including domestic cats. read more

Generally they don’t kill kittens just as generally most people do not kill their children. Male cats can be loving toward kittens and sometimes even try to nurse them. I have never had a male cat try to kill a kitten but I had a mamma cat start to eat her newborn kittens once and I have had a lot of kittens over the years. read more

Domestic male cats as well as male cats in the wild aren't known for their fathering skills. Other than siring as many kittens as possible, tom cats don't tend to get involved in the raising of the kittens. Male cats have been known to kill kittens, usually kittens that they didn't father. read more

Cats may sometimes do this with a first litter, because they haven’t yet learned to bond with the kittens, or because they are under stress, or can’t feed them for some reason. The behavior isn’t common, but it is a normal response to illness, stress or lack of resources. read more

Cats who do not have a maternal drive, whether male or female, may kill very young kittens simply because they resemble prey. And though I wouldn’t count on this - some male cats actually have gentle, supportive behaviors when it comes to babies. read more