On the internet, the answer to the question in the title is almost set in concrete and that answer is Yes. But is it correct? There are two or three things which indicate to me that it is not strictly correct to say that domestic cats are territorial. And please note that I’m specifically referring to domestic and stray cats because they are different creatures to most wild cat species.
The first point worth making is that a scientist who is often referred to in animal studies, S.L. Cromwell-Davis, writing in The Welfare of Cats states:
“In spite of the frequent references to territoriality in the cat, there is no good evidence that cats are territorial.”
Cromwell-Davis writes that animals that are genuinely territorial have a home range which they actively and consistently defend. In other words their home range is synonymous with their territory. They leave prominent signals on the borders of the territory. Further, home ranges which are adjacent do not overlap with theirs.
In contrast, with respect to domestic cats, home ranges often overlap and urine and faeces markers together with scratches on objects occur well within the home range along the paths used commonly by the cat and not on the borders of that parcel of land.
This does not indicate that the domestic cat is highly territorial. It is a bit of a spoiler because as stated it is almost a given judging by what you read and see on the Internet that domestic cats are territorial but I would question it.
Secondly, both feral cats and domestic cats are not asocial. For complete clarity I’ll define the word “asocial”. It means avoiding social interaction and being inconsiderate of or hostile to others.
Stray and indeed feral cats don’t act like this within colonies. They may form close relationships with other cats. They also show a variety of friendly behaviours (affiliative behaviours) such as rubbing against each other, playing a resting together, touching noses, greeting with tail up and grooming each other.
At locations where there is a food supply you will see colonies of feral cats sometimes and they cohabit in a reasonably harmonious way. These are not the behaviours of highly territorial animals living a solitary life.
With respect to domestic cats in multi-cat homes there is sometimes friction between the cats. This is because the cats are often unrelated and the cats do not regard themselves as part of a social group. Under these circumstances the cats can be regarded as a threat to each other with respect to territory and resources. This is a different sort of behaviour to that found in feral cat colonies which is a more natural situation.
There is perhaps another point worth mentioning. Ten thousand years of domestication must have had some impact upon the sociability of the domestic cat. It could be argued that the domestic cat has become more domesticated over that 10,000 years and therefore the innate desire to protect resources within an area of land might be less strong than it was originally. Domestication has rounded off the rough edges of their wildcat ancestor. This is the point that I’m making. But I am not even saying that the domestic cat’s wildcat ancestor is territorial either.
This is a discussion piece. However, I would conclude by saying that people should not say with complete conviction that domestic cats are territorial. There are plenty of signs which argue against that proposition. In the past I may have come to a different conclusion.