Adult cats rarely meow at each other; meowing is largely a way to talk to us. Some breeds, such as Siamese and Orientals, are naturally very vocal, and some individual cats are simply chatty.
What matters is change. A cat that starts meowing much more than usual, sounds distressed, or yowls at night when it never did before is telling you something has changed, whether that's its routine, its environment or its health.
Night-time yowling in senior cats is particularly common and often has a medical cause that can be treated.
