I have feral cats where I live, I feed them and give them water on a regular basis for two reasons, 1) so they don't starve or dehydrate and suffer and 2) so they don't need to kill other animals to survive. I've rescued and found homes for some of the kittens I was able to get on time and the ones that could not be socialized I did the spade and release approach. They are not flea ridden or diseased thank God and thanks to the fact that it's a good neighborhood with some decent and caring people. But how these cats became feral in the first place was because of irresponsible owners who abandoned their cats and other owners who did not spade/neuter their cats and let them outside to inevitably breed. Cats are NOT wild animals and are NOT meant to be outside. They are amazing, beautiful and HIGHLY intelligent and loving creatures and they are NOT to blame for any of this. The answer isn't in what to do with the cats, it's what to do with the OWNERS!!! Until people start thinking STRAIGHT and REALISTICALLY and approach the actual only SOURCE of the problem which is IRRESPONSIBLE OWNERS, this is a dead end conversation at it's WORST. Time to wake up people.
As far as dealing with the cats that have already been abandoned, the spade and release truly IS the ONLY humane approach and therefore SHOULD BE the ONLY option. We live in a sick speciesist world however, and sadly it is the most innocent beings that end up having to pay.
There needs to be strict laws (like there are with dogs) about letting your cats roam wildly for starters. It isn't safe for the cats, outdoor cats are vulnerable to disease, poisonings, wild animals, and human cruelty and also kill our declining bird population as well as other native animal. This is not the cat's fault, dogs would do the same thing, it is the OWNERS FAULT. So for all the neanderthals who want to take it out on the innocent victims; the helpless cats just being cats, go take some meds and try to think for 10 seconds.
Perhaps more importantly there needs to be STRICT laws on abandoning your pets! It is like abandoning a child. And if an owner lets their cat outside and he/she has kittens, those kittens should be legally linked to that or both owners and to leave those kittens outside should be considered abandonment.
The ONLY time any animal should be put down is if they are suffering to painful extents and nothing can be done and putting them down is the most humane approach (HUMANELY as in painless or virtually painless and quick methods only, no gas chambers, etc...) Otherwise the spade and release method is the way to go.
You can say you're "protecting them from suffering" by just killing them, but you don't go around culling homeless people do you? All life must be respected or you respect no life at all. And though the equality between all species is sadly approached the same way equality between all races was approached way back in the day, there is one thing no man can argue, that in pain and suffering, we are all equals.
Wake up people, stop blaming these poor cats, they are the VICTIMS of irresponsible and selfish human beings. The only problem here is people:
1) Irresponsible pet owners who let their cats roam outside not taking responsibility for the important animals they kill.
2) Irresponsible pet owners who don't spade/neuter their pets.
3) Irresponsible pet owners who knowingly let their pets out to breed and take no responsibility for their off spring.
4) Irresponsible pet owners who abandon their pets.
5) Animal breeders and kitten mills. There are TOO MANY cats without homes for one, when you breed or buy, a shelter animal dies. Secondly it is WRONG to profit off of another life. These are helpless babies we are talking about, to sell them for money is nothing short of ABANDONMENT, you don't know what will happen to them ultimately. And lastly, kitten mills just like puppy mills are a little piece of HELL on earth.
6) Careless and cruel people. People who see kittens under some abandoned shed and do nothing but go about their own everyday lives as if they have no moral responsibility or even the responsibility of being a citizen of wherever they may be, or rather the earth alone. And people who do horrifying and disgustingly evil things to these innocent animals such as poisoning, torturing, shooting, etc.... They're the problems more so than any feral animal that is continuously caused by man alone in the first place.
So PLEASE, can we start looking at the real problem here... PEOPLE.
Point one finger and 3 more are pointing back at you, quite the simplest of concepts yet one so arrogantly ignored by most human beings and THAT is why these problems continue and that is the only reason why they WILL continue.