There are more than 500 million domestic cats worldwide, and they have now superseded the dog as the number one pet. However, the human-cat relationship is much less well established than that of dogs and humans. Cats have been domesticated for approximately 10,000 years. But it is a tenuous relationship. With even modern domestic cats reverting back to feral free living individuals peacefully breeding with wild cats if human support is not available. Modern cat breeds have only been established for around a 150 years. And generally don't show the same extreme diversity of size and body type that we see in dogs. This relatively recent domestication is evident in some of the cats normal behaviors such as the retention of a strong predatory instinct. This is particularly important to consider with cats that don't have access to the outdoors. As providing appropriate mental stimulation and the opportunity to practice their natural hunting behavior is essential to meet the cat's emotional and physical needs. Free living cats are selectively social, living in colonies of mothers and daughters, with selected males allowed into the colony for breeding. This social structure is very dependent on availability of resources, such as food, within a given territory. And this is an important consideration when we think about how we keep our pet cats. Cats can find being forced to share living spaces with other cats very stressful and may compete for resources such as owner attention, food and access to litter trays. Neighboring cats can also be a great source of stress, particularly in highly populated areas, as individuals will often find themselves competing for outdoor territories with large numbers of other cats. Of course, some cats maybe very social towards each other. Especially if they are littermates or kittens that have been raised together. The socialization window for cats, is between two to seven weeks of age, so much earlier than in dogs. And if they are well socialized during this time, then they are more likely to be able to cope with new situations and changes to their environments. Cats within a household may form social groupings. And you can look out for signs that this has occurred. For example, cats that are comfortable in each other's company will often spend time grooming each other. Greeting each other nose to nose or sleeping curled up in the same spot. Knowledge of the number of social groupings within a household is important when it comes to ensuring the adequate provision of key resources, and we'll discuss this further later on. Cats have a very keen sense of smell, and the scent profile of their environment is extremely important. Cats will rub their cheeks on visitors, new furniture, and even on their returning owners to smear them with a natural pheromone. This cat scent is undetectable by humans, but to your cat, it's a way of ensuring that everything in their environment smells familiar. If there's a disruption to the scent profile of a house because of redecoration, lots of visitors, or the arrival of another pet, your cat may struggle to maintain a reliable scent profile and so may start to mark areas of <b>tension</b> with urine. This scent-marking behavior is known as spraying and often occurs with the cat standing in an upright position with the tail held vertical. Small bursts of urine are then deposited, and a quivering motion of the tail is often seen. Cats are solitary hunters, and as such, territory is very important to them. This is the case regardless of whether or not they have access to the outdoors. Cats will defend their territory and they will mark the boundary with their scent in the form of urine and feces. Beyond the territory is the home range. This is the area that the cat will explore and it will also be shared with other cats. The cat's core territory is the area within which the cat expects to be able to access all of the resources that it requires such as food, water and resting places. The core territory is not marked <b>by</b> the cat because it is situated within the defended territory. However, if the core territory is breached in some way, such as by an intruding cat, the cat may feel threatened and begin to defend the boundaries with scent marking behavior. This is something that we will discuss further during future weeks.