Our discussion on the killer instincts of domesticated cats was one of our most popular threads last month, but we held off on posting the latest round of emails until we could compile all of the previous stories into one place – here. So many readers have asked us to find a way to read an entire thread more easily, and, thanks to the Beast's generosity with interns, this is a first stab at doing that. You can read the entire thread in chronological order, rather than clicking on multiple links: "Your Little Purring Murderer". Let us know what you think. Another reader continues the discussion:

I own two cats that go outside, and I study behavior. Here's the question: Do you want your cat to live 20 years, guaranteed, looking out the window and wishing? Because they do. Bored, because you're not playing with them for three hours a day? Sleeping extra time and getting fat because there's nothing to do in your house? I have to respond when people claim their cats are happy inside. They compare them to hunter-gatherer humans? Well, let's go the other way – what does an indoor cat look like on that spectrum? The person stuck in the cubicle all day who comes home and can barely stay awake to watch TV, with terrible joints and no life. There's risk to the cat to letting them out, but that's not a great argument for not doing it. Preventing them from killing birds is a good reason; keeping your cat "happy" is not.

Another tries to provide the best of both worlds:

Like several other of your readers, my family keeps a cat outside as a mouser and are pleased, not dismayed, by killer tendencies.  We originally got cats when chipmunks kept tunneling under a brick patio, caving in the bricks on a daily basis.  They solved the problem.  And with a heated cathouse, our working pets enjoy a free life winter and summer.  It's a hard fact that living outside in a rural area exposes them to coyotes and other dangers and we've lost a few over the years.  We've even witnessed our cat being attacked by an owl and fall screaming from their claws, but mostly it's the cats posing a danger to birds, rabbits and pests.

Another has a story of remarkable perseverance:

I once had a cat whose ego was fully invested in self-perception as a warrior killer.  Frankie was a tuxedo Manx, and I was living in a large rural spread when I got him as a kitten, so I didn't even contemplate restricting his activities.  In fact, I was glad that he was killing the various furry vermin that ravaged my gardens.  When he was about a year old he went out into the woods one winter day and got caught in a squirrel trap.

By the time he returned home a few days later (presumably having been freed by whomever set the trap), his front right leg was cold and dead, and it was necessary to amputate it all the way to his shoulder.  Needless to say, he looked very bizarre with three legs and no tail.

I assumed that he would settle into a domestic lifestyle, lounging around the house, but the loss of his leg seemed to have a psychological effect that spurred him on to a desperate level of hunting.  He hadn't often brought home trophies before the loss of this leg, but afterward he was constantly depositing them on the doorstep.  It was heartbreaking watching him laboriously drag the carcass of a dead rabbit for a dozen yards, and he was often exhausted by the time he brought home the bunny, but it was obvious that he wanted me to see that he still had the ability to perform that function.

He also spent a lot of time on top of my dresser, gazing into the mirror and positioning his body so that the reflection didn't show him as a cripple.  There was no doubt in my mind that Frankie had a very specific physical image of himself, both before and after the amputation.  I've since watched lots of pets gaze at themselves in a mirror, but I've never seen one that was as mesmerized by his own reflection as Frankie was after he lost his leg.

Frankie only lived for about six months afterward, and he died of a heart attack on a hot summer day after chasing a rabbit in the field.  I really wish that I had prevented him from going outside after he lost his leg, but he seemed so miserable when I did try to keep him indoors that I thought it was better for his happiness to be able to continue hunting.

Another:

Our cat, Blackie Lawless, was an abandoned-pet-turned-feral which we "rescued", who survived on his hunting prowess before we adopted him (ie, coaxed him into our home). Even after he became domesticated, sleeping in our bed every night and cozying up to our two indoor cats, he still spent his days catching jack-rabbits, gophers, field mice and roof-rats whose populations were exploding in our Scottsdale, Arizona neighborhood. Our neighbors LOVE him for helping to maintain a balance when the fauna was decimating the flora – especially roof rats, which destroy citrus trees and nest in roofs eating electrical wiring and are the scourge of the greater Phoenix area. The typical option for eradicating them is poison, which endangers more than just the rats.

We are naturally ambivalent about some of his prized catches that also include the odd gambol quail, and we had to get used to the gruesome carnage (which was not easy) but on the whole, he has been an integral part of our neighborhood’s peaceful co-existence with nature.  He may be a purring murderer, but he is also a "working cat".

Another says that "sometimes, killer cats do their duty inside":

The killer cat thread reminded me of a story in the NYT a few years ago about bodega cats prowling the narrow aisles of shops in New York. There's a $300 fine for having a cat in a store, and a $300 fine for rodent feces. You can either get a weekly exterminator (and then have the smell of rotting rat carcasses) or a cat. There have been calls for the city to allow and regulated cats, but they haven't gone anywhere, apparently.