Animals usually clean their fur, feathers or other skin coverings. This is also a form of hygiene. Taking out other objects such as insects, leaves, dirt or twigs, are all forms of grooming. Among animals, birds spend a lot of time preening their feathers. They do this to remove ectoparasites, keep them in good condition, and waterproof them. Felidae cats are well known for their grooming, which they usually do by licking themselves. One of the reasons this is done is to remove all the scent on them so that they will not attract any predators. Cats groom so much that they often produce hairballs from the fur they accidentally swallow.