Kitty come home
The homing instinct is very strongly built into many animals, including cats. It's not unusual for people moving home to have to make frequent visits to their old home, (especially if the new location is not that far away) and spend some time trying to persuade their cats that they no longer live there. This is not so much a problem if it involves a few minutes' walk, but cats can get 'home' from much further away than that. Some cats have homing skills so well developed that they are capable of finding the way back home over immense distances- in extraordinary cases, over dozens or even hundreds of miles. Take Sooty for example. When his family moved over 100 miles away, he somehow managed to find his way back to what he regarded as home. Another extraordinary cat namedPilsbury , an eight-year old English Tom, refused to accept that he now lived eight miles away. He went 'home' and was returned forty times, by which point he and his frustrated humans must have been able to travel the route blindfolded. To get to his former home the indomitablePilsbury had to cross both busy roads and fields with herds of cattle, but even his persistence pales beside the record held by a tomcat named Ninja. In 1996 Ninja and his people moved from Utah to Washington State. Ninja obviously disapproved of his new home and disappeared shortly after arrival. A year later he turned in Utah at his former residence, after completing a journey of some some 850 miles.
No-one taught cats like Ninja how to find the way 'home'. Until these cats were moved to their new homes they had never made the journey, so it is something of a mystery how so many have found their way back. There are actually two types of 'homing instinct': the first where animals being able find a way to get home after being moved or lost outside their home territory is uncanny but possible, given cat's extraordinary sensory abilities such as small. However, no-one can fully explain 'psi trailing' where cats catch up with humans who have either accidentally or deliberately left them behind. One such story tells of a cat which was left in Chicago with friends while the family moved to New Orleans. The cat abandoned the friends and somehow managed to track down his humans in New Orleans. Anecdotal stories of this sort abound, but unlike stories of cats finding their way back home, we have yet to find a fully authenticated case of 'psi trailing'.
While researching homing instincts, Scientists in the USA have took a group of cats. These were sedated, so that they cats could not remember their journey. Then they were taken on a complex route which finished at a maze, in which the cats were left to wake up. The maze had 15 exits. The scientists were intrigued to discover that more often than not, the cat exited the maze at the closest point to their home. Older cats performed better than younger. Homing ability dropped off with distances greater than 7.5 miles from home.
A cat will return to her original home because cats do not like changes. They have spent time and effort securing their home range, negotiating access and spraying rights with other cats, and generally getting on top of things. Suddenly they are yanked from their known environment and have to start all over again. Cat's do not understand the necessities of changing homes for work or financial reasons. They know where they want to live, and if they get a chance, they'll go there. So why cats have a homing instinct is relatively easy to answer. How they put that motivation into practice is much harder to explain. One theory is that cats are sensitive to the earth's magnetic field. It is well known to scientists that the magnetic intensity of the Earth varies from point to point and differences in the magnetic field can be detected even over a short distance. Therefore it is possible that cats can read these magnetic changes and use them in choosing their direction. In fact this was tested in an experiment where a magnet was attached to a cat's body, and this showed that the homing ability was indeed disrupted as a consequence.
Although magnetic changes may be important in a cat's navigational system, cats may use multiple clues to find their home. For example,pigeons are thought to orientate themselves by the sun, and cats probably also have this as part of their built-in direction finder. Cats eyes are also more sensitive to a wider spectrum of light which they can use in navigation. Smell may be helpful for homing over relatively short distances, although that probably will not help a cat much beyond her natural range.
The homing ability (or perhaps the motivation) can weaken (at least to some extent) over time. This is why it is strongly recommended that when you move home, you should keep the cat safely indoors for a least 10 days to two weeks. This is particularly important if you move a relatively short distance away. Otherwise you will never be short of an excuse to pop back to your old house and to see how things are getting on. (You might as well collect your mail while you are at it.)