Spay gone wrong or adoption?
So last year around this time a pregnant feral cat showed up in my barn. I started feeding her and fed the babies after they were birthed. When they were eventually big enough to separate I caught all the babies (kept two and found homes for all the others) and then trapped the mom and had her spayed. She's been living in in the barn ever since where I leave food out for her.
This morning I went out to deposit her usual food and she had three probably four or five week old kittens with her... So called the vet to ask if it was possible the spay failed and he was pretty confident it did not. Considering how long ago we got her spayed and how quickly cats can get pregnant, I'm inclined to agree because I figured she would have birthed a clutch already if it did fail. So I'm wondering if it's known behavior for a spayed cat to adopt or look after another cats babies.