spayed cat male still bothers

Question
my female cats are spayed,there is a  stry male cat comes here and he chases them and bothers them all time,why is this?

Answer
Hi
the answer is simply instinct I'm afraid. I had a spayed female cat and for years a tom cat would come around to try his luck, she would have none of it.

The female cats still smell like female cats even though they are no on heat and that attracts the males i'm afraid.

best wishes kate