Why do I feel bad about killing a mouse?

[Domino Quartz]

So, there was a mouse living in my room. Was, because it is now dead. For at least a few weeks, it had been in there, either waking me up or keeping me awake at night by making scratching noises under my bed or rustling noises in the corner of my room. It was infuriating. I really wanted to get rid of this mouse so that I could sleep peacefully. Finally, yesterday evening I bought some mousetraps from my local supermarket. Then I baited one with a tiny piece of bread with marmite (chosen for its strong smell) on it, and set it in the corner of my room. When I woke up, I checked the mousetrap, and sure enough, there the mouse was, dead. I disposed of its body and washed the mousetrap, but I also felt really bad about it for some reason. The mouse just wanted somewhere warm to live (just so you know, I'm in the southern hemisphere and it's starting to get colder now as we head towards winter), and some food, and now it's dead. Why do I feel so bad about killing a mouse?

[Rynjin]

Killing another living thing is inherently pretty disturbing if you think about it, is why. It was alive and now it's been snuffed out just like that; just like you will be one day. It's a reminder of your own mortality and everybody else'. It doesn't stop people from doing it, and you can desensitize yourself over time, but it's ever really going to feel right. It's part of the reason I stopped going hunting.

[Tvtyrant]

So, there was a mouse living in my room. Was, because it is now dead. For at least a few weeks, it had been in there, either waking me up or keeping me awake at night by making scratching noises under my bed or rustling noises in the corner of my room. It was infuriating. I really wanted to get rid of this mouse so that I could sleep peacefully. Finally, yesterday evening I bought some mousetraps from my local supermarket. Then I baited one with a tiny piece of bread with marmite (chosen for its strong smell) on it, and set it in the corner of my room. When I woke up, I checked the mousetrap, and sure enough, there the mouse was, dead. I disposed of its body and washed the mousetrap, but I also felt really bad about it for some reason. The mouse just wanted somewhere warm to live (just so you know, I'm in the southern hemisphere and it's starting to get colder now as we head towards winter), and some food, and now it's dead. Why do I feel so bad about killing a mouse?
You have watched 100 times as many videos with anthropomorphic mice as you have killed mice, is my guess. Social animals have instinctive aversions to killing members of their own species, otherwise being social wouldn't really work. We get trained from birth to apply that instinct to a massive bevy of animals and objects, especially in kids programming.

[PopeLinus1]

Because we as a species are lucky. We have more control over our planet than any other species, because we understand the circumstances that we live in. We understand what threats are out there, and what we have to do to survive. Mice don't have that. What did that mouse understand? Clearly, it didn't know what a mousetrap was. What did it think about the world they lived in? Your room, your bed, it was nature to it. All it really must have understood was that it needed to eat.

And well, look how that turned out.

The really scary bit? It doesn't matter. How many mice die from mousetraps daily? How many people cared enough to post about it on the internet. I barely cared enough about a mouse dying to open this thread. And while we will talk about it, you'll forget, and I'll forget, and nothing that mouse did, including dying, will matter at all.

[Altair_the_Vexed]

So, there was a mouse living in my room. Was, because it is now dead. For at least a few weeks, it had been in there, either waking me up or keeping me awake at night by making scratching noises under my bed or rustling noises in the corner of my room. It was infuriating. I really wanted to get rid of this mouse so that I could sleep peacefully. Finally, yesterday evening I bought some mousetraps from my local supermarket. Then I baited one with a tiny piece of bread with marmite (chosen for its strong smell) on it, and set it in the corner of my room. When I woke up, I checked the mousetrap, and sure enough, there the mouse was, dead. I disposed of its body and washed the mousetrap, but I also felt really bad about it for some reason. The mouse just wanted somewhere warm to live (just so you know, I'm in the southern hemisphere and it's starting to get colder now as we head towards winter), and some food, and now it's dead. Why do I feel so bad about killing a mouse?
It's normal and natural to feel bad - and I'd say that feeling is to be embraced. If you could kill a mouse in cold blood, through planning and with forethought, without feeling at all bad, then I'd worry for you.

You deliberately planned to kill an animal with a trap. An animal whose life and motivations you have some empathy for, some understanding of. Yes, you did this for your own peace of mind and well-being, but now you're comparing your actions and the outcome with the level of inconvenience the mouse brought.
Was it proportionate to kill the mouse because it kept you awake? I'm not looking for an answer there, just voicing the question that's inherent in the OP.

If you'd seen the mouse suddenly, and hit it with a broom, you'd probably feel less bad about it - there'd be adrenaline, there'd be a feeling of achievement perhaps. But instead, you set a fatal trap that the animal had no chance of escaping, that exploited the basic drives of the mouse - drives you are clearly empathising with - to kill it.

A mouse is a mammal, so we share a lot of brain structure - that's apparent in the way they behave, the decisions they make and so on. Unlike an insect or a spider, we can imagine the mouse's mind. Of course, they have no higher thought processes, but we can see ourselves in the mouse - so it's normal and natural to feel regret for its death.

Despite saying all this, which might seem like I'm saying "You ARE bad for killing the mouse", you shouldn't worry about your feeling. I'd recommend that you accept it, understand it, and in future act with the knowledge that you will feel bad if you cause harm to other living creatures.
In the short term, just know that there are "humane" traps, that catch but don't kill mice, so you can release them later. I checked, and the NZ Department of Conservation don't treat mice as an invasive species, unlike rats.

Full disclosure: I'm a vegetarian and an animal rights advocate. I'm also compassionate to our differences of opinion about animal welfare, and people's rights to their normal cultural practices - so I'm not here to say "Animal traps bad!" - I just want to say that "Forget about it" is a poor choice.

[Domino Quartz]

Thank you all for your answers. They've given me a lot to think about.

[PopeLinus1]

Thank you all for your answers. They've given me a lot to think about.

Word of advice, don't think to hard about them. These are difficult times, and now especially is a bad time for sitting around thinking about death. If your going to be pondering the grim nature of life and death, do it later, when you can go to a park afterwards, or whatever flouts your boat.

[CheesePirate]

If you ever find yourself having to get rid of a mouse again and want to avoid feeling bad about it, there are non-lethal options (https://www.smsl.co.nz/shop/Eco-friendly+%26+Natural/Humane+Mouse+Trap+-+Live+Capture+Tip+Trap.html).

[ti'esar]

Despite (or maybe because) of my severe arachnophobia, I feel wracked with guilt whenever I kill a spider. So there doesn't strike me as anything remotely unusual about feeling bad about killing a mouse.

[warty goblin]

We live in an anthropologically strange moment in time where, at least in some societies, many people can go very long periods of time without personally having to kill anything that isn't some variety of small arthropod. Come to think of it, I can go a long time without needing to kill a bug anymore as well.

If you aren't used to it, being directly responsible for the death of a mammal or bird can be rather shocking. We just aren't used to seeing things like that die violently; the weird flat look of a dead body, that strange creeping sense that I did this and I really definitely can't take it back, it gets under the skin a bit. I remember the first time I helped slaughter a pig from said swine being alive and grunting to being roasted, and just how deeply unsettling it was how long the animal spasmed after it died. It was definitely dead; we shot it right through the brain then cut its throat basically to the spine, and it still took over a minute to stop moving - and the amount of blood was simply unreal. Seeing something that falls even vaguely into the 'like us' category turn into what is unmistakably a pile of dead flesh is, I think, inherently concerning when not accustomed to it.

The really astonishing thing is how fast one does habituate though. Next year at pig slaughtering time, it was just a mildly unpleasant feature of the morning's work.

[wilphe]

Humans very rarely get to see death these days, even the death of an animal.

It's not surprising that that might affect you.

[Darth Credence]

To this day, I feel bad about a mouse that I tried to save, close to 30 years ago. My GF at the time was crying when I got to her house, and it was because her stepdad had used one of the sticky traps to catch a mouse. I hate those things, because it seems like such a bad way to go. We took it outside, and tried everything we could think of to free it, but we couldn't get it done and the mouse died. I don't think about it often, but often enough that I only get live capture traps if I need them.
I don't see feeling bad about this as a character flaw - I think it means that you don't want to cause death and/or suffering for no reason, and that's a good thing. There is a difference between this and killing an animal for food - everything must eat, and eating other creatures is one way to fulfill that requirement. In this case, you weren't killing the mouse for food, you were killing it because it had invaded your space and was interfering with your life. Nothing wrong with that - mice can carry disease, and keeping them away from our living space is important in stopping the spread of some diseases. But to balance the guilt with still wanting to ensure that you keep them away, go with a live capture one, don't forget it's there, and release them somewhere they have a decent shot at living.

[veti]

In the short term, just know that there are "humane" traps, that catch but don't kill mice, so you can release them later. I checked, and the NZ Department of Conservation don't treat mice as an invasive species, unlike rats.

I have a trap like that. It's a metal box, about the size of a biscuit tin, with a glass top and a kind of miniature maze inside. The mouse has to climb a small ramp to get in, then it snaps back up behind them and traps them inside.

You can release the mouse afterwards, but make sure you take it well away from your house before you do it. Ideally, away from everyone else's houses as well, because they may not be as humane as you.