Why Do They Cover/Uncover the Litter Box?

This occasional series explores the reasons for cats’ often intriguing behavior. If you would like to suggest a topic, please write CatWatch Editor, 800 Connecticut Ave., Norwalk, CT 06854, or email catwatcheditor@cornell.edu.

One of the enduring mysteries of cats’ behavior is why they cover their feces after eliminating. One theory is that they’re trying to hide their presence from predators, as cats in the wild are believed to do, but no studies support that idea. Another suggests that the behavior is an indication of cats’ fastidiousness, but that doesn’t explain fastidious cats who leave urine or feces uncovered. The real answers are far more complicated.

“Kittens instinctively cover their eliminations by 1 month of age by raking loose dirt over the excrement,” says Pamela J. Perry, DVM, Ph.D., a graduate of the Cornell University School of Veterinary Medicine and lecturer on small animal behavior there. “The specific site and substrate tend to be learned from the queen. It is believed that the odor of the feces initiates the burying behavior. In fact, some cats will cover the feces of other cats in the household.”

Leaving a Message. Feral cats usually bury feces within their core area — the area where they spend most of their time — but do so less often in other areas, Dr. Perry says. “Uncovered feces tend to be found along frequented routes or on elevated areas, which may send a message to other cats about a particular cat’s sex or state of health. Feral cats also tend to use multiple areas for eliminating, which may help prevent parasite transmission. It is possible that domestication has affected this burying behavior and that may explain why some household cats don’t cover their feces.”

Having a cover on a litter box doesn’t affect whether cats bury their feces, but it can determine whether they will use the litter box, Dr. Perry says. “Most cats prefer uncovered litter boxes, probably because they have more room to move around and because the odor isn’t trapped inside the box. In addition, cats cannot see out very well in a covered box, making them more vulnerable to being ambushed by another cat.” In this case, instinct prevails.