How does a cat use its whiskers?
The usual answer is that the whiskers are feelers that enable a cat to tell whether a gap is wide enough for it to squeeze through, but the truth is more complicated and more remarkable. In addition to their obvious role as feelers sensitive to touch, the whiskers also operate as air-current detectors. As the cat moves along in the dark it needs to manoeuvre past solid objects without touching them. Each solid object it approaches causes slight eddies in the air, minute disturbances in the currents of air movement, and the cat's whiskers are so amazingly sensitive that they can read these air changes and respond to the presence of solid obstacles even without touching them.
The whiskers are especially important – indeed vital – when the cat hunts at night. We know this from the following observations: a cat with perfect whiskers can kill cleanly both in the light and in the dark. A cat with damaged whiskers can kill cleanly only in the light; in the dark it misjudges its killing-bite and plunges its teeth into the wrong part of the prey's body. This means that in the dark, where accurate vision is impeded, healthy whiskers are capable of acting as a highly sensitive guidance system. They have an astonishing, split-second ability to check the body outline of the victim and direct the cat's bite to the nape of the unfortunate animal's neck. Somehow the tips of the whiskers must read off the details of the shape of the prey, like a blind man reading braille, and in an instant tell the cat how to react.
Photographs of cats carrying mice in their jaws after catching them reveal that the whiskers are almost wrapped around the rodent's body, continuing to transmit information about the slightest movement, should the prey still be alive. Since the cat is by nature predominantly a nocturnal hunter, its whiskers are clearly crucial to its survival.
Anatomically the whiskers are greatly enlarged and stiffened hairs more than twice the thickness of ordinary hairs. They are embedded in the tissue of the cat's upper lip to a depth three times that of other hairs, and they are supplied with a mass of nerve-endings which transmit the information about any contact they make or any changes in airpressure. On average the cat has twenty-four whiskers, twelve on each side of the nose, arranged in four horizontal rows. They are capable of moving both forwards, when the cat is inquisitive, threatening, or testing something, and backwards, when it is defensive or deliberately avoiding touching something. The top two rows can be moved independently of the bottom two, and the strongest whiskers are in rows two and three.
Technically whiskers are called vibrissae and the cat has a number of these reinforced hairs on other parts of its body – a few on the cheeks, over the eyes, on the chin and, surprisingly, at the backs of the front legs. All are sensitive detectors of movement, but it is the excessively long whiskers that are by far the most important vibrissae, and it is entirely apt that when we say that something is 'the cat's whiskers' we mean that it is rather special.
Why do cats' eyes glow in the dark?
Because they possess an imageintensifying device at the rear of their eyes. This is a lightreflecting layer called the tapetum lucidum (meaning literally 'bright carpet'), which acts rather like a mirror behind the retina, reflecting light back to the retinal cells. With this, the cat can utilize every scrap of light that enters its eyes. With our eyes we absorb far less of the light which enters them. Because of this difference cats can make out movements and objects in the semi-darkness which would be quite invisible to us. Despite this efficient nocturnal ability it is not true that cats can see in complete darkness, as some people seem to believe.
On a pitch black night they must navigate by sound, smell and the sensitivity of their amazing whiskers.
Why do cats' eyes contract to a vertical slit?
Reducing the pupils to slits, rather than tiny circles, gives the cat a more refined control over precisely how much light enters the eyes.
For an animal with eyes sensitive enough to see in very dim light it is important not to be dazzled by bright sunlight, and the narrowing of the pupils to tight slits gives a greater and more accurate ability to cut down the light input. The reason why cats have vertical slits rather than horizontal ones is that they can use the closing of the lids to reduce the light input even further. With these two slits the vertical one of the pupil and the horizontal one of the eyelids working at right angles to one another, the feline eye has the possibility of making the most delicate adjustment of any animal, when faced with what would otherwise be a blinding light.
Confirmation of the fact that it is the nocturnal sensitivity of the cat's eyes that is linked with the contraction of the pupils to slits, is found in the observation that lions, which are daytime killers, have eyes that contract, like ours, to circular pinpricks.
Can cats see colours?
Yes, but rather poorly, is the answer. In the first half of this century scientists were convinced that cats were totally colour-blind and one authority reworked a popular saying with the words: 'Day and night, all cats see grey." That was the prevailing attitude in the 1940's, but during the past few decades more careful research has been carried out and it is now known that cats can distinguish between certain colours, but not, apparently, with much finesse.
The reason why earlier experiments failed to reveal the existence of feline colour vision was because in discrimination tests cats quickly latched on to subtle differences in the degree of greyness of colours and then refused to abandon these clues when they were presented with two colours of exactly the same degree of greyness. So the tests gave negative results. Using more sophisticated methods, recent studies have been able to prove that cats can distinguish between red and green, red and blue, red and grey, green and blue, green and grey, blue and grey, yellow and blue, and yellow and grey. Whether they can distinguish between other pairs of colours is still in dispute. For example, one authority believes that they can also tell the difference between red and yellow, but another does not.
Whatever the final results of these investigations one thing is certain: colour is not as important in the lives of cats as it is in our own lives. Their eyes are much more attuned to seeing in dim light, where they need only one-sixth of the light we do to make out the same details of movement and shape.
How does a female cat deal with her new-born kittens?
As the nine-week gestation period comes to an end the pregnant cat becomes restless, searching around for a suitable den or nest in which to deliver her kittens. She looks for somewhere quiet, private and dry.
In a house, strange noises emanate from cupboards and other nooks and crannies as the cat tests out a variety of suitable sites. Suddenly, from being increasingly ravenous, her hunger vanishes and she refuses food, which means that the moment of birth is imminent – perhaps only a few hours away. At this point she disappears and settles down to the serious business of bringing a litter of kittens into the world.
Some cats hate interference at this stage and become upset by too much attention. Others – usually those that have never been given much privacy in the house – do not seem to care much one way or the other.
The happy-go-lucky ones will co-operatively move into a specially prepared birth-box, with soft warm bedding provided and easy accessibility for a human midwife, should one be needed. Other cats stubbornly refuse the perfect nest-bed offered them and perversely disappear into the shoe-cupboard or some such dark, private place.
Giving birth is a lengthy process for the average cat. With a typical litter of, say, five kittens, and with a typical delay of, say, thirty minutes between the arrival of each one, the whole process lasts for two hours, after which both cat and kittens are quite exhausted. Some cats give birth much more quickly – one kitten per minute – but this is rare.
Others may take as long as an hour between kittens – but this is also uncommon. The typical time delay of about half an hour is not an accident. It gives the mother long enough to attend to one kitten before the next arrives.
The attention she gives the new-born baby consists
of three main phases.
First, she breaks away the birth sac (the amniotic sac) which encases the kitten as it emerges into the world. She then pays special care to the cleaning of the nose and mouth of the new-born, enabling it to take its first breath. Once this crucial stage is over, she starts to clean up, biting through the umbilical cord and eating it, up to about one inch from the kitten's belly. The little stump she leaves alone, and this eventually dries out and finally drops off of its own accord. She then eats the afterbirth – the placenta – which provides her with valuable nourishment to see her through the long hours of total kittencaring that now face her, during their first day of life. After this she licks the kitten all over, helping to dry its fur, and then she rests.
Soon the next kitten will appear and the whole process will have to be repeated. If she grows tired, towards the end of an unusually large litter, the last one or two kittens may be ignored and left to die, but most female cats are amazingly good midwives and need no help from their human owners.
As the kittens recover from the trauma of birth, they start rooting around, searching for a nipple. The first feed they enjoy is vitally important because it helps to immunize them against disease. Before she produces her full-bodied nutritional milk, the mother provides a thin first-milk called colost~m, which is rich in antibodies and gives the kittens an immediate advantage in the coming struggle to avoid the diseases of infancy. It is also rich in proteins and minerals and its production lasts for several days, before the mother cat starts to produce the normal milk supply.
How do kittens avoid squabbling when feeding from the mother?
Within a few days of birth each kitten has developed an attachment to its own personal nipple, which it recognizes with ease. Amazing as it may sound, this is possible because each nipple has a special smell.
We know this because if the belly region of the mother cat is washed by her human owner, so that it is cleansed of its natural fragrance, the kittens fail to find their favourite nipples. Instead of peacefully taking up their usual stations, they become disorientated. Confusion reigns and squabbling occurs.
It is remarkable to think that in the 'simple' world of the very young kitten there is odour detection based on differences so subtle that they can label each nipple as clearly as name-cards on school lockers, and that in this way orderly sharing can be maintained at feeding time.
At what rate do kittens develop?
When they are born the kittens are blind and deaf, but have a strong sense of smell. They are also sensitive to touch and soon start rooting for the mother's nipples. At this stage they weigh between two and four ounces, the average birth weight being roughly three-and-a-half ounces.
They are about five inches long.
By day four, the kittens have already started the paw-treading action which helps to stimulate the mother's milk-flow. At the end of the first week of life their eyes begin to open and they have by now doubled their body weight. As they approach the end of their first month of life, they show the first signs of playing with one another.
They can move themselves about with more efficiency and can sit up.
Whatever colour their eyes will be later in life, at this stage all kittens are blueeyed and remain so until they are about three months old. Their teeth are beginning to break through at the age of one month.
At roughly thirty-two days, they eat their first solid food, but they will not be weaned until they are two months old. (Wild cats take longer to wean their kittens – about four months.) During their second month of life they become very lively and intensely playful with one another.
Inside the house, pet kittens will use their mother's dirt tray by the time they are one-and-a-half months old. Play-fighting and play-hunting become dominant features at the end of the second month.
In their third month of life they are in for a shock. The mother refuses to allow them access to her nipples. They must now make do entirely with solids and with liquids lapped from a dish. Before long their mother will be coming into oestrus again and concentrating on tom-cats once more.
In their fifth month the young cats begin to scent-mark their home range. They are shedding their milk teeth and exploring their exciting new world in a less playful manner. The chances are that their mother is already pregnant again by now, unless her human owners have kept her indoors against her will.
At six months, the young cats are fully independent, capable of hunting prey and fending for themselves.
Why does a cat move its kittens to a new nest?
When the kittens are between twenty and thirty days old, their mother usually moves them to a new nest site. Each kitten is picked up firmly by the scruff of the neck and, with mother's head held as high as possible, is carried off to the fresh location. If it has to be transported over a long distance the mother may grow tired of the weight and let her head sag, switching from carrying to dragging. The kitten never objects, lying limp and still in its mother's jaws, with its tail curled up between its bent hind legs. This posture makes the kitten's body as short as possible and reduces the danger of bumps as it is unceremoniously shunted from old nest to new one.
As soon as the mother arrives at the new site she has chosen, she opens her jaws and the kitten drops to the ground. She then returns for the next kitten and the next, until the whole litter has been transported.
After the last one has been moved, she makes a final trip to inspect the old nest, making doubly sure that nobody has been left behind.
This suggests that counting kittens is not one of the cat's strong points.
It is usually stated that this removal operation is caused either by the old nest becoming fouled or because the kittens have outgrown it.
These explanations seem logical enough, but they are not the true reason. A cat with a large, clean nest is just as likely to set about moving its litter. The real answer lies with the wild ancestors of the domestic cat. In the natural environment, away from canned cat food and dishes of milk, the mother cat must start bringing prey back to the nest, to arouse the carnivorous responses of her offspring. When the kittens are between thirty and forty days old they will have to begin eating solids, and it is this change in their behaviour that is behind the removal operation. The first, old nest had to be chosen for maximum snugness and security. The kittens were so helpless then and needed protection above all else. But during the second month of their lives, after their teeth have broken through, they need to learn how to bite and chew the prey animals brought by the mother. So a second nest is needed to facilitate this. The primary consideration now is proximity to the best food supply, reducing the mother's task of repeatedly bringing food to her young.
This removal operation still occurs in domestic cats – if they are given half the chance – despite the fact that the feeding problem has been eliminated by the regular refilling of food dishes by their human owners. It is an ancient pattern of maternal feline behaviour which, like hunting itself, refuses to die away simply because of the soft lifestyle of domestication.
In addition to this 'food-source removal pattern', there are,of course, many examples of a cat quickly transporting her litter away from what she considers to be a dangerous nest site. If human curiosity becomes too strong and prying eyes and groping hands cannot keep away from the 'secret' nest, strange human smells may make it an unattractive abode.
The mother cat may then search for a new home, simply to get more privacy. Moves of this kind can take place at any stage of the maternal cycle. In wild species of cats, interference with the young at the nest may result in a more drastic measure, the mother refusing to recognize them as offspring any more, and abandoning them or even eating them.
What happens, in effect, is that the alien smells on the kitten's body make it into an alien 'species' – in other words, into a prey species and the obvious response to such an object is to eat it. Domestic cats rarely respond in this way, because they have become so used to the scents and odours of their huma
n owners that they do not class them as alien. Kittens handled by humans therefore usually remain 'in the family', even if they have acquired new scents.
How do kittens learn to kill?
The short answer is that they do not need to learn how to perform the killing action, but it does help if they get some instruction from their mother. Kittens reared by scientists, in isolation from the mother cat, were able to kill prey when given live rodents for the first time. Not all these kittens succeeded, however. Out of twenty tested, only nine killed and only three of those actually ate their kills. Kittens reared in a rodent-killing environment, where they could witness kills but never saw the prey eaten, were much more successful. Eighteen out of twenty-one such kittens tested were killers and nine of these actually ate their kills.
Interestingly, of eighteen kittens reared in the company of rodents, only three became rodent-killers later on. The other fifteen could not be trained to kill later by seeing other cats killing. For them the rodents had become 'family' and were no longer 'prey'. Even the three killers would not attack rodents of the same species as the one with which they were reared. Although it is clear that there is an inborn killing pattern with kittens, this pattern can be damaged by unnatural rearing conditions.
Conversely, really efficient killers have to experience a kittenhood which exposes them to as much hunting and killing as possible. The very best hunters are those which, as youngsters, were able to accompany their mother on the prowl and watch her dealing with prey.
Catwatching Page 7