Cats are curious little creatures. They are completely tame, but have retained several of their wild instincts. Its domestication story is really interesting and sheds light on how this happened. One of the wild traits that they have maintained is their fierce territoriality and with it the need to watch over it. These two instincts can lead to behavior problems, especially when an intruder is involved.
For a cat, his house and everything he can see around him is his domain. Cats will spend most of their waking hours looking through windows to keep an eye on their territory. As long as this territory is not challenged, cats will be content to just watch the birds and lizards, but as soon as it is compromised, things can get a little tense.
The individual temperament of your cat along with the behavior of the intruder will influence the harshness of your cat’s reaction. You might think that watching the stranger hunt your cat’s territory would be the worst case scenario, but most cats are more annoyed by strangers looking at them. This is called visual bullying, and it can be a source of difficult to diagnose behavior problems.
Behavior problems
When your cat is struggling to maintain its territory, it will likely begin to display territory-based behaviors as it would in the wild. It is common for it to scratch inappropriately, especially around the edge of your cat’s territory. If your cat is strictly indoors, you may find that curtains and window and door frames are the most affected by this abuse. Scratching is visual and odor-based marking, and in nature it can be very effective in maintaining border control. I have an article that explains what you can do if scratching becomes destructive.
Urine tagging is a means of sharing territory when the cat population in an area is too high for individual territories. Because cats are not social creatures and because they do their best to avoid conflict, they developed a message system to stay out of touch when their territories overlap. Urine marks can tell other cats a surprising amount about each other. In the case of territory protection, urine markings can tell other cats when the resident cat was last there and how often they return. For cats in the wild and at home, this helps minimize potential dangerous encounters.
Spoiling or leaving unburied stools is another issue that you may notice that falls into the timeshare category. It’s a less common communication tactic in house cats, but it certainly sends a message to other cats about when they may be expecting the resident cat. Middening should not be confused with inappropriate toilet training. One way to determine the difference is if the poop is left in the open and no attempt was made to cover it.
What you can do
If you feel like your cat is struggling with a territory violation, do your best to determine where his territory is compromised. From there, you need to determine what you can do to prevent other cats from being seen or staring at your cat.
Perches such as sheds, fence posts, and cars can provide neighborhood cats with the perfect place to sit and watch your cat. Since you cannot easily move any of these things to prevent the cat from perching, you will need to try to obstruct your cat’s view. Closing the curtains to the problem will not help, as it is very easy for your cat to get around them. Consider closing the blinds for as long as the cat is around or keeping it out of that room.
If your cat is upset with passing cats, you can try cutting off their visual territory by placing potted plants and garden furniture to limit how far they can see and therefore claim. I have heard of other more intense strategies involving motion activated sprinkler systems. If you find that no amount of rearrangement prevents your cat from marking and suffering emotional distress, then those solutions might be worth investigating.