Although most cats bury their waste, not all cats do. From a behavioral standpoint, feral cats cover their droppings when in strange territory or to acknowledge the higher position of another cat that uses that range. Other cats may leave droppings uncovered as a signal that they "own" the territory, and proclaim their dominance.
In most cases, cats that live with humans and use litter boxes tend to cover up their waste, sort of an acknowledgement that the human is the dominant property owner in the house. When more than one cat is in the household,
sometimes one will start signaling ownership by leaving waste uncovered.
Cats learn to cover their waste when they are very young, by copying their mother. Of course, they'd cover up in her presence! But in many cases of young kitten adoptions, the kitten leaves her mother too early to learn all the proper feline etiquette about potty duty.
Other times, the type of cat litter may influence the desire to dig. Larger particles may be rough and harder on paws, so the cat stops digging. The smaller
particles of clumping-type litter, or a lighter-weight material might prompt better digging habits.
