Feral cat colony

A couple days ago, I found a black cat outside the gas station.  I went in the gas station and bought it some starkist tuna salad (because regular tuna was in cans and I didn’t have an opener).  I believe the cat was feral instead of a stray because it did not come to me even though I had food and waited until I got back in the car to eat the tuna.  I went back yesterday expecting to feed the same cat but there was a different one!  It was a gray tabby and acted the same way as the other cat in that it did not come out of the bushes to eat until after I got in my car.  Now I am wondering how many feral cats live in these bushes?  The gas station is on a hill so behind the building, the ground slopes down for a while and is covered in shrubs and brush.  It’s possible they aren’t feral and just didn’t come to me because they’ve only met me once but I’ll have to go back frequently and see if they still act this way to find out.  If they’re strays, I’ll call the shelter but if they’re feral, I think I might try to trap them and get them neutered and then return them to the same spot.  There’s lots of birds in the area so we want to make sure the cats don’t keep breeding and killing them lol.  Songbirds are already struggling as is since there is no profit in protecting them because they aren’t game species that everyone pays to hunt.  I’ll probably make more updates on my encounters with the cats and if there are more.