Just a note about "why" male cats may kill newborn kittens: the survival mechanism involved, in terms of passsing on genetic material, involves the fact that if a mother cat loses a litter early, she will most likely go into an early estrus ("heat") so that she will conceive again. If a male cat kills the kittens and then hangs around so that he can mate with her, he can be assured that *his* genetic material gets passed down. Of course none of this is in the cat's conscious mind - it's just built into the behavior of the species, as a way of ensuring that the male has a good chance at getting his line preserved. Or at least that's the widely received theory.