Do male cats kill and eat kittens? I think you have to answer this question in two parts.
True feral cats
As for the wild version of domestic cats, namely true feral cats, there’s a bit of a myth about sex-mad tomcats destroying litters of kittens in order to get the female back on heat again quickly. It’s not true. When scientists observed European wildcats, which belong to the same species as domestic cats, they found that the males were not kitten-killers but sometimes participated in rearing the young.
For example, one tomcat was seen to carry food to the entrance of the den in which the female was giving birth. Dr Desmond Morris says that the chances of a tomcat in the wild coming across a female in a den is remote, however. He believes that four things can happen when a tomcat encounters kittens in the wild, (1) the male cat simply ignores the kittens or (2) the male behaves paternally towards the kittens as has been observed in wildcats in captivity or (3) the female attacks the male when he approaches her nest and drives him away which stops an encounter between the male cat and the kittens so we don’t know what would have happened and (4) the male cat kills the kittens.
The fourth reaction is the one which people think happens but Dr Morris says that it is extremely rare. The first three forms of encounter normally take place but sometimes the male cat does kill kittens and Dr Morris provides an intriguing reason as to why.
He believes that the female cats sometimes experience a “false heat” a few weeks after they have given birth. If the tomcat is nearby he becomes excited but the female normally drives him off. As the male is desperate he may try and mount one of the female’s kittens to mate with her. The male cat does not attack the kitten but when mounting the kitten he grabs him or her by the neck as is normally the case when mating with a female cat (this keeps the female quiet).
However, when mating with a small kitten, the kitten remains still because kittens are programmed to remain still when their mother grabs her by the scruff of the neck in order to carry them to a new den. The male cat therefore receives a signal that he can mate with the kitten because she is still but he cannot copulate with a tiny kitten. He struggles and bites the back of the kitten’s neck too hard which ultimately kills the kitten because of her delicate anatomy.
The death is an accident and because the kitten is dead it may trigger another reaction. Dead kittens are often devoured by their parents apparently to keep the den clean and for other reasons. So the kitten is eaten, a consequence of the original mistake. This gives the impression that tomcats are engaged in cannibalism and that they are savage psychopathic creatures determined to kill and eat their own children.
We know that male lions sometimes commit infanticide. They do it when taking over a pride of lions because they acquire the cubs of the previous older male that they have ousted. The new male may react by killing the cubs rather than waste his time rearing the offspring of the departed father. The female comes on heat again quite quickly and can be made pregnant by the “invading” male. The female then carries the cubs of the new male lion.