In the case of the cat approached by a dog, there is both intense aggression and intense fear.
It is this conflicting, double mood that gives rise to the special display. The cat borrows the most conspicuous element of its anger reaction – the stiff legs – and the most conspicuous element of its fear reaction – the arched back – and combines them to produce an 'enlarged cat' display. If it had borrowed the other elements – the straight back of anger and the low crouch of fear – the result would have been far from impressive.
Aiding its 'transformation display' is the fact that the animal, while stretching its legs and arching its back, also erects its fur and stands broadside-on to the dog. Together these four elements make up a compound display of maximum size increase. Even if the cat retreats a little, or advances towards the dog, it carefully keeps its broadside-on position, spreading its body in front of the dog like a bullfighter's cloak.
During the arched-back display the cat hisses ominously, like a snake, but this hissing turns to growling if it risks an attack. Then, when it actually lashes out at the dog, it adds an explosive 'spit' to its display. Experienced cats soon learn that the best policy when faced with a hostile dog is to go into the attack rather than run away, but it takes some nerve to do this when the dog is several times the cat's weight. The alternative of 'running for it' is much riskier, however, because once the cat is fleeing it triggers off the dog's hunting urges.
To a dog a 'fleeing object' means only one thing – food – and it is hard to shift the canine hunting mood once it has been aroused. Even if the fleeing cat halts and makes a brave stand, it has little hope, because the dog's blood is up and it goes straight for the kill, arched back or no arched back. But if the cat makes a stand right from the first moment of the encounter with the dog, it has a good chance of defeating the larger animal, simply because by attacking it, the cat gives off none of the usual 'prey signals'. The dog, with sharp claws slashing at its sensitive nose, is much more likely then to beat a dignified retreat, and leave the hissing fury to its own devices. So, where dogs are concerned, the bolder the cat, the safer it is.
Why does a cat hiss?
It seems likely that the similarity between the hiss of a cat and that of a snake is not accidental. It has been claimed that the feline hiss is a case of protective mimicry. In other words, the cat imitates the snake to give an enemy the impression that it too is venomous and dangerous.
The quality of the hissing is certainly very similar. A threatened cat, faced with a dog or some other predator, produces a sound that is almost identical to that of an angry snake in a similar situation.
Predators have great respect for venomous snakes, with good reason, and often pause long enough for the snake to escape. This hesitation is usually the result of an inborn reaction. The attacker does not have to learn to avoid snakes. Learning would not be much use in such a context, as the first lesson would also be the last. If a cornered cat is capable of causing alarm in an attacker by triggering off this instinctive fear of snakes, then it obviously has a great advantage, and this is probably the true explanation of the way in which the feline hiss has evolved.
Supporting this idea is the fact that cats often add spitting to hissing. Spitting is another way in which threatened snakes react.
Also, the cornered cat may twitch or thrash its tail in a special way, reminiscent of the movements of a snake that is working itself up to strike or flee.
Finally, it has been pointed out that when a tabby cat (with markings similar to the wild type, or ancestral cat) lies sleeping, curled up tightly on a tree-stump or rock, its coloration and its rounded shape make it look uncannily like a coiled snake. As long ago as the nineteenth century it was suggested that the pattern of markings on a tabby cat are not direct, simple camouflage, but rather are imitations of the camouflage markings of a snake. A killer, such as an eagle, seeing a sleeping cat might, as a result of this resemblance, think twice before attacking.
Why does a cat wag its tail when it is hunting a bird on a lawn?
The scene is familiar to most cat-owners. Through the window they see their cat stalking a bird by creeping stealthily towards it, head down and body low on the ground. This cautious crouching attempt to be as inconspicuous as possible is suddenly and dramatically ruined by the animal's tail, which starts swishing uncontrollably back and forth through the air. Such movement acts like a flag being waved at the bird to warn it of approaching danger. The intended victim takes off immediately and flies to safety, leaving a frustrated feline hunter staring up into the sky.
Cat-owners witnessing this scene are puzzled by their cat's inefficiency. Why does the cat's tail betray the rest of the body in this self-defeating way? Surely the wild ancestors of the domestic cat could not have survived such a serious flaw in their hunting technique?
We know that conspicuous tail-wagging in cats is a social signal indicating acute conflict. It is useful when employed between one cat and another and is then an important part of feline body language. But when it is transferred into a hunting context, where the only eyes that will spot the signal are those of the intended prey, it wrecks the whole enterprise. So why has it not been suppressed in such cases?
To find the answer we have to look at the normal hunting sequence of the cat. This does not take place on an open lawn and is less well known to cat-owners than it might be because it involves a great deal of waiting and hiding. If owners do happen on a hunt in progress they will automatically disrupt it, so that there is nothing more to observe. The disturbed prey escapes and the cat gives up. So for a casual observer the whole sequence is not easy to study. It requires some systematic and secretive catwatching. When this is undertaken, the following points emerge:
First, the cat makes a great deal of use of cover. It spends much time lying half-hidden in undergrowth, often with only its eyes and part of its face visible. The tail is usually completely hidden from view.
Second, it never attempts to pounce on a prey until it is very close to it. It is not a prey-chaser. It may make a few stalking-runs, rushing forward in its flattened posture, but it then halts and waits again before pouncing. Third, its normal prey is not birds but rodents. A careful study of feral cats in the United States revealed that birds accounted for only 4 per cent of the diet. The excellent eyesight of birds and their ability to fly straight up in the air to escape make them unsuitable targets for domestic cats.
Together these points explain the dilemma of the suburban cat hunting a bird on a lawn. To start with, the open, manicured lawn robs the cat of all its natural cover, exposing its whole body to view. This is doubly damaging to its chances. It makes it almost impossible for the cat to creep near enough for its typical, close-quarters pounce without being seen. This puts it into an acute conflict between wanting to stay immobile and crouched, on the one hand, and wanting to rush forward and attack, on the other. The conflict starts its tail wagging furiously and the same lack of cover that created the conflict then cruelly exposes the vigorous tail movements to the frightened gaze of the intended prey.
If the attempt to hunt a bird on an open lawn is so doomed to failure, why does the cat keep trying? The answer is that every cat has a powerful urge to go hunting at regular intervals, but this urge has been severely hampered by advances in human pest control. In town and cities and suburbs, the rodent population that used to infest houses and other dwellings has been decimated by modern techniques. Garden birds may be pests, but their appeal to human eyes has protected them from a similar slaughter. As a result, the rodent-hunting cat finds itself today in an unnaturally mouse-free, bird-rich environment. It cannot utilize its natural hunting skills under such conditions. It is this state of affairs that drives the cat on to crouch hopelessly but compulsively on open lawns, staring longingly at elusive birds. So when it waves its tail at its prey on these occasions, it is not the cat which is a stupid hunter, but we who have unwittingly forced a clever hunter to attempt an almost impossible task.
Why does a cat chatter its teeth when it sees a bird through the window?
Not every owner has observed this curious action, but it is so strange that it is a case of 'once seen never forgotten'. The cat, sitting on a window-sill, spots a small bird conspicuously hopping about outside and stares at it intently. As it does so it begins juddering its teeth in a jaw movement which has variously been described as a 'tooth-rattling stutter', a 'tetanic reaction' and 'the frustrated chatter of the cat's jaws in the mechanical staccato fashion'. What does it mean?
This is what is known as a 'vacuum activity'. The cat is performing its highly specialized killing-bite, as if it already had the unfortunate bird clamped between its jaws. Careful observation of the way in which cats kill their prey has revealed that there is a peculiar jaw movement employed to bring about an almost instantaneous death.
This is important to a feline predator because even the most timid of prey may lash out when actually seized, and it is vital for the cat to reduce as much as possible any risk of injury to itself from the sharp beak of a bird or the powerful teeth of a rodent. So there is no time to lose. After the initial pounce, in which the prey is pinioned by the strong claws of the killer's front feet, the cat quickly crunches down with its long canine teeth, aiming at the nape of the neck. With a rapid juddering movement of the jaws it inserts these canines into the neck, slipping them down between vertebrae to sever the spinal cord. This killing-bite immediately incapacitates the prey and it is an enactment of this special movement that the frustrated, window-gazing cat is performing, unable to control itself at the tantalizing view of the juicy little bird outside.
Incidentally, this killing-bite is guided by the indentation of the body outline of the prey – the indentation which occurs where the body joins the head in both small birds and small rodents. Some prey have developed a defensive tactic in which they hunch up their bodies to conceal this indentation and in this way make the cat miss its aim. If the trick works, the cat may bite its victim in part of the body which does not cause death, and on rare occasions the wounded prey may then be able to scrabble to safety if the cat relaxes for a moment, imagining that it has already dealt its lethal blow.
Why does a cat sway its head from side to side when staring at its prey?
When a cat is preparing to pounce on its prey it sometimes sways its head rhythmically from side to side. This is a device employed by many predators blessed with binocular vision. The head-sway is a method of checking the precise distance at which the prey is located. If you sway your own head from side to side you will see how, the closer an object is, the more it is displaced by the lateral movements. The cat does this to refine its judgment, because when the rapid pounce forward is made it must be inch-accurate or it will fail.
Why does a cat sometimes play with its prey before killing it?
Horrified cat-owners have often experienced the shock of finding their pet cats apparently torturing a mouse or small bird. The hunter, instead of delivering the killing-bite of which it is perfectly capable, indulges in a cruel game of either hit-and-chase or trap-and-release, as a result of which the petrified victim may actually die of shock before the final coup de grace can be delivered.
Why does the cat do it, when it is such an efficient killing machine?
To start with, this is not the behaviour of a wild cat. It is the act of a well-fed pet which has been starved of hunting activity as a consequence of the 'hygienic' environment in which it now lives – neat suburbs or well-kept villages where the rodent infestation has long since been dealt with by poison and human pest control agencies. For such a cat, the occasional catching of a little field mouse, or a small bird, is a great event. It cannot bear to end the chase, prolonging it as much as possible until the prey dies. The hunting drive is independent of the hunger drive as any cat-owner knows whose cat has chased off after a bird on the lawn immediately after filling its belly with canned cat food. Just as hunger increases without food, so the urge to hunt increases without access to prey. The pet cat over-reacts, and the prey suffers a slow death as a result.
On this basis, one would not expect feral cats which are living rough or farm cats employed as 'professional pest-controllers' to indulge in play with their half-dead prey. In most cases it is indeed absent, but some researchers have found that female farm cats do occasionally indulge in it. There is a special explanation in their case. As females, they will have to bring live prey back to the nest to demonstrate killing to their kittens at a certain stage in the litter's development. This maternal teaching process will account for an eagerness on the part of females to play with prey even though they are not starved of the hunting process.
There is one other explanation for this seemingly cruel behaviour.
When cats attack rats they are quite nervous of their prey's ability to defend themselves. A large rat can give a nasty bite to a cat and has to be subdued before any attempt is made to perform the killing-bite.
This is done by the cat swinging a lightning blow with its claws extended. In quick succession it may beat a rat this way and that until it is dazed and dizzy. Only then does the cat risk going in close with its face for the killing-bite. Sometimes a hunting cat will treat a small mouse as if it were a threatening rat, and start beating it with its paws instead of biting it. In the case of a mouse this quickly leads to a disproportionately savage pounding, with the diminutive rodent being flung to and fro. Feline behaviour of this type may appear like playing with the prey, but it is distinct from the trap-and-release play and should not be confused with it. In trap-and-release play the cat is inhibiting its bite each time. It is genuinely holding back to prolong the hunt. In hit-and-chase attacks on mice the cat is simply overreacting to the possible danger from the prey's teeth. It may look like cruel play, but in reality it is the behaviour of a cat that is not too sure of itself. Even after the prey is nearly or completely dead, such a cat may continue to bat the victim's body around, watching it intently to see if there is any sign of retaliation. Only after a long bout of this treatment will the cat decide that it is safe to deliver the killing-bite and eat the prey.