If you have an fertile female cat, nature will always provide the male. Sometimes it seems the darn things are born pregnant, like tribbles!
There was a feral cat living under the shed behind my house in Durango. She would have five kittens in the spring, the coyotes would eat them all, and she'd have another five the next spring. The cycle of life and death continues. People have imaginings about 60 cats in two years should get out of the city and expose themselves to life.