Kittens may be born at any time of the year. Among wild cats, the time of birth depends upon the kind of cat and the climate of the area. Domestic cats in the tropics may have kittens at different times from those in northern climates. In the United States, most mothers have two litters a year, and kittens are born in the spring or late summer.
A domestic cat carries the unborn kittens inside her body for about 65 days. As the time for birth approaches, she hunts for a quiet, safe place to have her kittens. Her owner may supply a cardboard box.
Most kittens are born headfirst, but some may be reversed. The average litter consists of four kittens, but there may be only one or as many as seven. They are born one at a time, usually about half an hour apart. Each is enclosed in a thin transparent sac, which the mother immediately breaks and removes with her teeth and tongue. The newborn kitten weighs about 3 1/2 to 5 ounces (100 to 142 grams) and is about 3 inches (8 centimeters) long.
Most cats need little assistance during kittening; however, many are comforted by the presence of their owners. Occasionally the sac will be tough, and the mother may be unable to break it. If this happens, the owner should break it, as the kitten may suffocate.
At birth the kitten has no teeth, the eyes are closed, the ears lie flat against the head, the tail is short and triangular, and the fur is soft and downy. The kitten begins to get its first teeth when it is two or three weeks old, and all 26 of them have grown in by the time it is two months old. These baby teeth are replaced by the 30 permanent teeth when the animal is about six months old.
The eyes begin to open when the kitten is about 8 to 12 days old. All kitten's eyes are blue. It may take several months for the eyes to change to their permanent color.
Kittens begin to crawl out of their nest when they are about a month old. The rate of growth and the ultimate size and weight depend greatly on inheritance and nutrition. Most six-month-old domestic cats weigh about 5 pounds (2.3 kilograms). They reach full skeletal development by the time they are about a year old. Female cats usually become sexually mature when they are six to eight months old, and males become sexually active a few months later.
Like many other mammals, cats like to play. Kittens stalk one another as make-believe enemies and have sham battles. Even old cats enjoy short periods of play. Some scientists believe that in play the animals practice the skills and techniques important for their survival. Cats are hunters and stalkers. Many games they play show their ability to creep close to prey, then swiftly spring upon it.
Most kinds of cats are skillful climbers, escaping into trees for safety or climbing to lie in wait for prey. The domestic cat climbs not only for safety but also for sport. It will streak up and down a tree or scale the draperies or mantelpiece indoors with equal skill. Inexperienced kittens often dash up trees only to find that they do not know how to get down. A cat rarely falls from a tree.
Given time, it will usually discover how to get down.
Reliable information on the average life-span of cats does not exist and would be impossible to obtain. Well-cared-for, neutered house pets, however, may live into their teens. Some may reach the 20s, and a few have been reported to live into the 30s.