What are cats saying when they put their tails up?
Posted Apr 19, 2011
As a total newbie to blogging, I’m going to keep this short. And as I’ve spent the best part of the last two years working on a book about dogs, I’m going to start this blog with some thoughts about cats. As a biologist interested in interactions between pets and their owners, I’m especially fascinated by how our companion species employ their species-typical communication behaviour to try to communicate with us.
Cats the world over perform the “tail-up” signal, in which they raise their tails to the vertical when approaching other animals, and especially humans. For years this has been called a “greeting” signal – because it usually happens at the beginning of an interaction. But is this label any more than a convenient anthropomorphism? Is it just a convenient shorthand for “a piece of behaviour that occurs at the beginning of an interaction”, or does it also imply that the cat is expressing an emotional state, or an intention – or both?
As part of her research, a former graduate student of mine, Charlotte Cameron-Beaumont, once performed some interesting tricks on my cats (and others’) to try to ascertain what the “tail-up” meant. She cut cat-shaped silhouettes from black paper, some with the tail up, some horizontal, taped them to a baseboard (aka skirting board, for any Brits reading this) in the cat’s home, and then let the cat into the room. If the silhouette’s tail was up rather than down, the cat was more likely to approach it, and more likely to raise its own tail. Tail-up therefore seems to signal intention, and may even induce an emotional change in the recipient, possibly decreasing any anxiety that the other cat might attack it.
In a journal paper published a couple of years ago in Behavioural Processes, Simona Cafazzo and Eugenia Natoli additionally proposed that it was an indication of inferiority; that by raising its tail, a cat “shows the recognition of the higher social status of the individual to whom (it) is directed”. When two cats meet, tail-up is often followed by one cat rubbing the other, and it’s fairly well established that, in cat society, rubbing flows from smaller to larger individuals. But does the cat itself “recognise the higher social status” of the other? Do cats actually have a concept of “higher social status”, or is “status” simply a description that we as humans apply to animal societies? Since some cats perform tail-up to dogs, does this mean that cats think of dogs as having “higher status”? Biologists seem to be uncertain as to the point in the evolution of the mammalian brain where a concept of “status” becomes possible – some place the divide between primates and non-primates, which would mean neither the domestic cat nor the domestic dog would qualify.
So while the tail-up signal is commonplace and easily recognised, its interpretation, in terms of the cat’s inner life, is less straightforward. Leaving that aside, tail-up is also interesting from an evolutionary perspective. Conventional wisdom has it that domestication has only impoverished the signalling repertoires of animals, never enriched it, so the cat’s tail-up may be unique in the sense that it may have actually appeared during domestication. Small cats of other species, such as the jungle cat, the caracal and Geoffroy’s cat, body-rub one another without any preliminary tail-up. Descriptions of African wildcats, the elusive wild ancestor of our domestic cat, mention rubbing but not tail-raising. Quite how the tail-up signal might have evolved (whether during domestication or earlier) is something of a mystery. But it’s possible that it’s the only instinctive signal that’s evolved as a consequence of man’s activities.