The previous owners of our house catproofed the long garden all around. At the time they did it there was a colony of feral cats lurking in the small holding over the back but they are long gone. There are lots of pet cats around so we make sure the fencing is maintained because we feed birds and enjoy gardening.
Very occasionally, over the years, a cat has managed to get in and, of course, is trapped. When we see that we open the gate and chase the cat out.
We have had more trapped cats this year than all the years before so DH examined the fencing carefully and cannot find how a cat could get in. A newish neighbour on one side has said he hates cats and their mess from time to time. We have come to suspect that he is dropping cats into our garden. I'm not sure what his point is because we would see them eventually and chase them out.
If it is him he can drop a cat over out of our sight at the side of the house so we can't keep watch. It seems such an odd thing to do - I think I should maybe say something - but what?