Why are Calico Cats Female?

Why are calico cats female? Can they ever be male? And what about tortoiseshell cats – are they always female too? What about folklore and these cats? This page answers all these questions.

What are Calico and Tortoiseshell Cats?

The names refer to the coat colors and patterns of the cat’s coat, rather than a specific breed.

In other words, they aren’t recognized breeds as such, although a lot of recognized pedigree breeds can have tortoiseshell or calico markings (e.g. Persian, Manx, American Shorthair, British Shorthair, Exotic Shorthair).

The coat of the calico and tortoiseshell cat consists of a blend of three different colors:

Calico: White, black and orange

Tortoiseshell: Orange, black and cream or brown

In both cases, the coat is actually determined by a mix of two colors only – red and black. Creams are a blend of these colors.

Why are Calico Cats Female?

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Calico Cat

The chromosomes that determine the sex of a cat (and human!) are the X and Y chromosomes.

Females have two X chromosomes and males have one X and one Y.

The genes that determine coat colors in cats are known as sex-linked – that is, they are carried on the X chromosome only. So the X chromosome will either carry the gene for a red color or the gene for a black color.

Female cats have two X chromosomes, therefore they can carry both colors – i.e. the red color on one and the black on the other. When this happens, a calico or tortoiseshell cat is the result.

Male cats only have one X chromosome, therefore they can usually ONLY carry the red color or the black color.

Can Male Cats Ever be Calico or Tortoiseshell?

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Tortoiseshell Cat

Yes – but it’s very rare (around 1 in 2000 to 3000 depending where you read it), and it only occurs if there is an abnormality in the genetic make-up of the cat.

Very occasionally, a male cat will have three sex chromosomes – two X and one Y. When this happens, they can show both the red and black colors in their coat, because they are carrying them on the two X chromosomes.

Male cats with the extra X chromosome are usually sterile.

Calico Males and Folklore

Because male torties and calicos are so rare, they have a fascinating history in terms of folklore, superstitions and good luck omens. For example:

  • The Celts believed having a male tortie in their home brought good luck

  • The English (bless us) believed that rubbing a wart or boil with a male tortoiseshell’s tail would remove the wart – BUT only if it was done in May! All I could think of when I heard this was poor cat!

  • Japanese sailors liked tortie males on their boats and ships because they believed they brought good luck and protected them from storms and ghosts

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