Cats in captive colonies at animal shelters, often form close friendships which last for many years. Eagle shared an enclosure with 11 other 'unhomeable' cats. The other cats frequently rubbed against Eagle and chose to sit close to him. When Eagle died, the relationship between the other cats broke down and the colony fragmented into several small groups. The super-sociable Eagle had been the glue that held them together.
Cats rub against their companions to mingle their scents and reinforce the bond.
Biologists studying farmyard colonies noticed that lower ranking cats often rubbed against higher ranking cats. Rubbing also has a hierarchical function and a cat's social standing can be measured by the number of times other cats rub against it. Rubbing, nose-bumping greetings and sitting close to other members of the cat's 'family' are not actions caused by keeping cats in 'unnatural proximity' to other cats. All of these activities have been observed among cats living in feral colonies. Behaviourists studying both urban and rural colonies found that the cats formed 'family groups' rather than remaining solitary.