I've got 6 kittens. Mom, dad, 3 tom kittens and one female kitten. They are now 1 year old.

The female one is neutered.

First Dad left me, then another kitten. Why is obvious. One of the kitten, a big one, terrorize all his brothers.

Finally another 1 year old kitten is gone and I panicked. Now, every day, I got to travel 400m, calling that "lost kitten" and pretty much bring it back to the house. Which is kind of silly.

All because my biggest kitten is mean to him. Yet, there are plenty of other kittens that do well and just stay outside my house just fine without picking a fight with my biggest kitten.

Why? They are brothers and used to play together. I mean, I am nice to my own bro, we hunt for mates together. Why is my tom cat so different?

Basically I want to ask why one of my tom cat is much more mean to his own brother than to other tom cats.

  • 4
    Ai there any reason you're not neutering your tom cats (1-year-olds and other adults are not kittens). Your problems would be pretty much solved if you did.
    – brhans
    Aug 6, 2018 at 19:15
  • 6
    You already asked almost the same question here and got an answer for it. Please don't ask again.
    – Elmy
    Aug 6, 2018 at 19:20
  • That question ask why my tom cat is leaving me. I know the answer already. He is afraid of his bro. This question ask why his bro is so mean.
    – user4951
    Aug 6, 2018 at 20:28
  • 3
    Different(ish) question - same answer. In general, un-neutered toms don't play well together.
    – brhans
    Aug 6, 2018 at 20:44
  • 3
    You may wish to read How to Ask for some tips on asking a great question. You already have a great answer on your other question about Tom cats by YElm which explains why they leave. If you question can't be answered by that answer, please make it clear why. If the answer to your other question is not satisfactory, then please edit that first question rather than making another.
    – Henders
    Aug 8, 2018 at 8:38

1 Answer 1


Here are some good resources to read about cat behavior:

For this answer I will recite the article The social structure of cat life

A cat’s territory consists of a core area, or den, where it feels secure enough to sleep, eat, play and potentially enjoy social interaction. This forms the hub of the territory which is the area beyond the core area that the cat actively defends against invasion from others. Beyond this lies the home or hunting range that constitutes the extent of the area over which the cat will roam.

This means every cat has their own territory and will fight off any cat comming into their core territory. From your description, I'd say your tomcat has declared your home to his territory and fights off all of his brothers.

Feral cats (cats which live without help from man) can and will form small colonies based around available food sources. This does not inevitably happen, and some will live singly, but it is not uncommon for small groups of co-operating females and kittens (matrilinear colonies) to develop.
Male cats are not commonly part of the small colonies, and they tend to exist on the periphery with large territories that may overlap several groups of females.

This means that female cats sometimes live together, but male cats usually don't. If they are neutered, they don't produce as much male hormones anymore and act more like a female, so neutered male cats may live together in a group.

Aggression most commonly occurs as male kittens reach sexual maturity and are excluded from the group, or between males and females as the tom ‘patrols’ his territory. [...] Mature males interact differently, and this is usually characterised by agonistic interaction, avoidance or tolerance, and not by friendly interactions.

This is what happened with your cats. One (the troublemaker) probably has more male hormones, so he is more dominant and aggressive to his siblings. He decided that he doesn't want to live with his family anymore, but that your house is his territory. Instead of leaving the house and letting the other cats live with you, he makes everyone else leave the house.

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