No tipped ears. What would that mean? I'll take email to the spca that's a no kill shelter.
As the person above me said, tipped ears indicates someone has trapped them and had them spayed or neutered. Please make sure that the SPCA really is a
no kill shelter, just because it's an SPCA doesn't necessarily mean they won't euthanize the harder-to-adopt out kitties when they need space for friendlier cats.
Also, you should try to see if anyone else in your neighborhood/area are feeding the cats. For a while there was a feral colony in the development I lived in, it started as some people letting their unaltered cats go outside, then nature takes over. There were people on a few different blocks feeding and watering the cats. Eventually we started taking care of the cats because our family are "cat people", so we learned about trap-neuter-release (or TNR for short), got them all fixed and fed them and kept them watered. After a while the cats started mostly staying in our yard for the guaranteed safety, food and water. We were able to socialize many of them and took them to North Shore Animal League, a true no-kill shelter, where they could get adopted. At the end, when we moved we had to leave behind 9 remaining cats. The new family that moved in knew beforehand about the "community cats" (a nicer way than saying feral!) and they and the next door neighbor continued to feed and water them.
TL;DR - There may be other people feeding them. If you can get them into a real no-kill shelter, that's great. If not, as long as your coop and run are built predator safe, they shouldn't be a bother to your hens, and will eventually move on to a new feeding grounds.