Why Male Calico and Tortie Cats Are So Rare

Recently we stumbled upon an article about an extremely rare male calico kitten up for adoption in Silicon Valley. Less than 0.1% of all calicos or torties are male. And, it’s likely this kitten, named Sherman, or any other male calico or tortie was born sterile.


http://patch.com/california/redwoodcity-woodside/unicorn-cat-makes-its-way-silicon-valley

‘Unicorn Cat’ Makes Its Way to Silicon Valley Animal Shelter

By Renee Schiavone (Patch Staff)

A very special kitten has found his way to a Silicon Valley animal shelter, and now representatives are hoping someone will be willing to give him a forever home.

Sherman is a male calico cat. Which is apparently really rare.

Dr. Andrea Berger, who is a veterinarian at the Humane Society Silicon Valley, says the chances of a calico cat being born male is less than 0.1%.

“It’s like a unicorn! I’ve been involved with shelters for 20 years and I have never seen one,” Berger said.

The four-month-old kitten recently arrived with the HSSV, as a transfer from one of their sister shelters, which was full.

“We work with shelters in the area to help alleviate the strain on resources when shelters are too full and when there’s an animal who needs a little extra help getting adopted,” a spokeswoman told Patch.

Anyone interested in adopting Sherman can stop by the Sunnyvale Neighborhood Adoption Center, inside Petco at 160 East El Camino Real. The adoption fee is $175.

By the way, shelter representatives say the little fur ball is very personable and friendly– and he’s a sucker for people and wand toys.


We asked guest writer and over all “one smart cat” Newton to give us the science behind the rarity of male torties and calicos. Here you go!

Newton’s Perspective: Calico Genetics

My namesake, Sir Isaac Newton, was a renowned physicist and mathematician. Although some credit him with inventing the cat flap to protect his experiments from light exposure (http://www.straightdope.com/columns/read/3156/did-isaac-newton-invent-the-cat-door), I doubt that he actually knew much about cats. That’s not surprising since we are WAY more complicated than physics! Recently my insatiable cat curiosity led me to a book about a male calico cat titled “Cats are not Peas” – https://www.goodreads.com/book/show/1358214.Cats_Are_Not_Peas. Well, that seems pretty obvious. I thought this was about genetics, not gardening. But what I read was far more complex than I imagined.

Have you ever met a male calico cat? If you said no I am not surprised. Less than one percent of all calico cats are male. But before I go any further, let’s define calico. Calico is a color pattern. When I think “calico” I see a cat that is predominantly white with patches of orange and black. However, this is only one variation. The key is having both orange (or beige) and black (or grey) colors.

The genetic code for black and orange colors is located on the X chromosome. Females have two X’s (XX), while males have an X and a Y (XY). If a female kitten gets both an orange and a black X then she will be calico XoXb. A male kitten from the same litter would get either an orange or a black X with the following results.

The only way for a male to have both orange and black colors is through a genetic mishap that gives him three chromosomes XoXb Y instead of two XoY or Xb Y. This is called Klinefelter Syndrome in humans and generally results in feminization and sterility.

So now you know why male calico cats are so rare. But I’m sure you’ll agree, all cats are special, no matter what color they might be.

Comments are closed.