Missing Feral Cat & Kittens in Ithaca

Hi--A feral cat and her two kittens, about 2-3 months old, has gone missing from my home, where they ate several times a day in my driveway. It is quite unusual for something like this to happen, even though sometimes a single feral cat may go for a few days. The mother is black with a small white patch on her chest, as is one of the kittens; the other kitten is all black. They were always very hungry. The mother tended to hiss but was not aggressive, just scared. I am quite concerned about them, as they hung out around my house and always wanted to eat their fancy feast. I was planning to trap them and get them fixed and possibly adopted. Now they're just gone. I live on Oak Hill Road in Cayuga Heights in Ithaca. If anyone has a sighting please contact me.