A recent study concluded that house cats aren't really satisfied with the kibble and/or canned cat food you give them. They also take a huge toll on native species of animals.
Now, I'm not a cat hater. My roommate is a diminutive black tuxedo cat I have named Squeaky due to her frequent (and sometimes almost constant) vocalization.
However, since getting her, I've come to realize what a perfect little predator she is. People refer to cat-like reflexes and boy are they right. They can strike out with their front paws blindingly quickly. Cats are sprinters not marathoners. In a short dash, they are impressively quick. Their senses are keen, especially hearing dogs have better noses, but cats have better ears.
Cats are pounce predators and their ability to leap is phenomenal. Squeaky can easily jump up and land on a flat surface 4 feet off the floor. And she's just 6 months old. She can jump higher if the surface has something she can get her front claws into. If she can grab onto something with her front feet, she'll probably manage to wrestle the rest of her body up.
Their spines are extremely flexible, which is what gives them their leaping and pouncing abilities. If I pick Squeaky up by cupping my hand under her belly, she bends in the middle as if she were a towel. Dogs have relatively little spine flexibility except for the coursing breeds (greyhounds, whippets, salukis, etc.), but even they can't match the flexibility of a cat.
One surprise in the aforementioned study that was brought to light in a TV report I saw a few months ago was that cats actually prey less on birds than thought. It turns out cats kill far more snakes, lizards, frogs and other cold-blooded prey than birds. 41% to be exact.
After the reptilian and amphibian prey items come the small mammals most people would probably assume make up the largest part of the toll. It turns out mice and other small animals make up just 25% of the menu. Next comes insects and worms, 20%. The remainder of about 12% comes from birds,
Now, cat owners in the United States are urged to keep their cats indoors not only for the protection of the natural prey items but to protect the cats. A cat can deal with a small dog but once you get to medium-sized dogs, the cat tends to be the prey item. And of course, cats aren't very smart when it comes to cars. You have the phenomenon of the "sailcat," which is a cat whose carcass has been run over so many times that you could sail it like a frisbee.
The study covered outdoor cats, and one interesting finding was that only 30% of outdoor cats engage in hunting as a regular activity. Outdoor cats according to this article constitute about 40% of cats in the United States. Feral cats are becoming a big problem in some parts of the country as detailed here.
Interestingly, attitudes vary greatly between Great Britain and the United States. Apparently, according to this article, in GB animal shelters actually instruct owners to give their cats outdoor time. In the US (and I experienced this when I picked Squeaky out at the local shelter) owners are implored to keep their cats indoors, mostly for the kitty's safety.
Now, people who want to ban cats seem not to believe in natural selection, which tells us that predators tend to take out mainly the weak and stupid members of a species, thus improving their gene pool.
It's argued that cats are a non-native species, but cats are in good company. Nobody I'm aware of is railing against the common house sparrow (aka English sparrow) as a non-native species. What is native tends to adjust itself over time. Did you know that camels first arose in the Americas, though now they are found almost entirely in North Africa and Asia. Species move around.
Horses, cattle, honey bees, and other non-native species are accepted in North America. When this happens, a curious change in language happens. We switch from using the pejorative term "invasive species" to the same sort of neutral or laudatory terminology we use for truly native animals.