Feral kittens 1st winter

They've been trapped, neutered, ears clipped, and shots. I want to keep them warm with a heated shelter, and with plenty of high protein food, and plenty of water.

Winston, the littlest guy, all black disappeared a month ago.
I hope I (we) gave him the best life a little feral could have. I cried for a couple of days, and my heart stays heavy.  In his memory, spay and neuter, please. They deserve better.