Small species are extremely vulnerable to predation and competition. They cover their feces and sometimes their urine in order to disguise the odor, especially if they are near the den – kittens are always at risk. They tend to be secretive and hard to find/see. The ancestors of domesticated cats were definitely small enough to be vulnerable to other predators and many of the same behaviors have carried over.
Adult animals will “spray” to mark their territory as a warning to interlopers and as an advertisement for mates. Spraying is a specific muscular effort that has to be learned and perfected – you will often see juvenile animals trying and unable to get anything to come out. These markings are typically not in the area of the den and are not directly associated with waste elimination.
Larger species do not hide their presence – they are the top of the food chain. They often spend a lot of time and effort announcing/delineating their territory to rivals and potential mates. In addition to chemical signals (spraying), they also verbalize, scratch their scent into tree bark, and use prominent geologic features to present themselves visually.
From here