I love cats. I think they are beautiful, affectionate creatures, but when my last cat died I decided I would rather have birds in the garden than a cat in the house.
A recent scientific survey on the TV news revealed that our domestic cats are more destructive to the environment than the feral cats in the bush.
I have been able to witness this destructiveness in my own street. Some years ago my nextdoor neighbour brought home two kittens. That spring I happened to see the whole local blue wren family lined up along a fence, there were five juveniles and the alpha pair (wren censuses are difficult as they move around a lot and the hens and juveniles are impossible to distinguish from each other). By the end of summer only the alpha male and one male juvenile were still alive.
So I know it sounds harsh, but looking at the situation without sentimentality, it would be much better for the environment if the organisations caring for cats euthanised the cats in their care rather than rehome them.