Can you remember a time before you had cats? Did you imagine a peaceful, quiet scene with the mellow cat basking in a sunny window while you relaxed with the morning paper/iPad? Perhaps you adopted a cat and achieved this scene of household harmony. Having one cat was so close to nirvana that you wanted more of a good thing and introduced another cat to the household. Suddenly, the atmosphere of your home changed to mayhem. What happened?
Tossing a new cat into a household with one or more established cats without prior planning can lead to all sorts of fun things such as yowling stand-offs, fights, protest poops (a term my sister-in-law coined) and territorial spraying on all your favorite furniture and belongings, including your shoes and underwear. Contrary to popular opinion, the behavior is not vindictive. It is normal behavior for an anxious, stressed cat.
The established cat has no warning that all its high-value items are about to be shared with another cat. Cats, whose ancestors were solitary hunters, do not easily share items such as food and water bowls, litter boxes and prime basking spots. If another cat comes into the territory to use high-value resources, there will be a lot of vocalization, followed by a hiss, swat or bite if the intruder does not leave. In a home, the new cat is trapped in an untenable situation. It can’t leave, and it is intruding on the established cat. It is highly stressed by being dropped into the new environment and encroaching on another cat through no plan of its own.
Cats will tolerate living in a group if they have to because of an excellent food source. Feral cat colonies will form outdoors because there is a source of food. If food is scarce, a cat will leave and hunt rather than fight because cats are natural solitary hunters and avoid confrontation if at all possible. However, an established group of cats will discourage and fight off an intruder. It is normal to do so.