[Rhiannon]

Cat are naturally roaming and hunt many animals including birds. If songbirds can't fly away fast enough then they are dinner. My cat has been bombed by mocking birds for years and has yet to bag one. He does try. The only birds he gets are those use nest over my doorway.
Cats are especially useful in getting rid of mice, rats, and rabbits. Small vermin. They do not prey excessively against birds.

Cat also often take off their collars. My older cat gets rid of his collar in a day. I have given up trying to keep a collar on him.

Car

[Marauder]

If songbirds can't fly away fast enough then they are dinner.

Bingo, evolution in action: Birds and other prey get faster and are more alert. When I see a pile of feathers in mmy yard, I know it was a slow bird.

My 16-year-old cat was born of feral parents and is instinctively more wary than an ordinary cat, and does help with rodent control. He likewise refuses to wear his collar.

If I had a problem with cats and their prey, it would be lizards, which are responsible for more insect control than a lot of people realize. I also wish cats could learn to control grackles and sparrows more effectively.

[Trust but Verify]

My sister lives in a semi-rural area where many people will keep a couple of horses or goats, chickens, and the like. She had horses and goats but currently raises just poultry.

They have two barn cats that wandered into the yard one day and decided to stay. They do not bother the chickens at all, however she has had oppossums getting into the barn and stealing eggs. The barn cats are not feral, just semi-domesticated and they do a great job keeping rodents under control. One of the barn cats has gone missing in the last couple of weeks. My sister fears one of her neighbors took this hunting proposal to heart and killed the cat.

[RedBloodedAmerican]

When I was a kid my neighbor buddy had a cat who had its ears picked off by mockingbirds. Shredded stumps, it was amazing.

[Richard-SIA]

Feral cats are predators!

Feral cats can decimate native bird populations.

They are quite fond of egg's, chicks, and birds too young to fly far enough to escape.
They make a huge dent in some species populations, particularly ground nesting species such as Ducks, Quail, Pheasant, Chuckar....

If the native bird species suffers a calamitous drop, the eco-nuts move in, demanding protection for the new "endangered species"!
Think what THAT does for your property values, and local control of issues.

Feral cats are to be shot on sight!