Q: My cat makes clucking sounds when she watches a fly on the wall... what does that mean?
A: The cat, not really recognized as a particularly vocal animal, actually has many different forms of vocalizations. The well known and characteristic meow is the typical all-purpose greeting. The soft buzzing sound created by the muscles of the larynx are usually associated with a happy cat, though they might also purr when stressed or hurt.
Most cat owners know when to give their cat attention or when it is time to feed her (at least in the cat’s opinion) called a “murmur”. They know when the cat is not happy by a “growl” or “hiss” and most veterinarians are familiar with the sound of a really angry cat by a loud and intense shriek – those emotions are differentiated not only by different body language but also by the different tones and noises.
Your cat displays a typical hunting sound, called the chatter, this is a high pitched, teeth chatter that can be heard also when the cat is restrained from hunting or she can not reach the fly on the wall. It is a good sound and you could give your cat some interactive toys to play with. There are many different toys on the market or you can make your own. Make some do-it-yourself food dispensing toys or create puzzle boxes made from cardboard boxes. Cut slits in the top of the box just a little wider than your cat's paw then put treats or a catnip toy inside for him to fish out through the slits. You can make fun toys out of cardboard paper towel or toilet rolls. Some cats also like a cat "fountain"/automatic water feeder. Another fun game he might enjoy is a ping-pong ball dropped into a dry, empty bathtub or a laundry basket.