Calico and tortoiseshell cats
You might have heard that calicos are sassy and that tortoiseshells have “tortitude.”
You might have heard that all calico and tortoiseshell cats are female.
You might wonder if calico is a breed of cat, and want to know where you can get one.
Well, here’s a chance to learn whether any of your preconceptions about calico and tortoiseshell cats are true!
What are calico and tortoiseshell cats?
The words “calico” and “tortoiseshell,” when referring to cats, are just descriptions of coloring. It’s like saying you have a black cat or a tabby cat. A calico or tortoiseshell cat might be one of any number of breeds, or no particular breed at all. The words only describe the color of the fur.
A calico cat has a three-colored coat: typically, large patches of orange, black, and white. Some calicos look white-washed, as if someone rinsed some of the color out of their hair. These cats are “dilutes,” which means that they have a gene that reduces the intensity of the pigments in their fur. They’re still calicos, but the blacks are more gray (referred to as “blue”), and the oranges are more cream or gold.
A tortoiseshell does not have any big patches of white. A tortoiseshell typically has a mottled coat of black and orange or, if they’re dilutes, gray and cream.
How did calicos and tortoiseshells get their names?
In most of North America, we call tri-colored cats calicos because their hued fur reminds us of multicolored calico fabric.
Outside of the United States, however, most people call a calico cat a “tortoiseshell and white," which is an accurate description.
If you’re in Quebec, you’ll call a calico a chatte d’Espagne, which is French for “cat of Spain.”
In Japan, a calico is a mikeneko, or “triple-fur cat.”
And in the Netherlands, you’ll refer to a calico as a lapjeskat, which is Dutch for “patches cat.”
A calico with diluted coloration is sometimes called a calamanco or clouded tiger (I love that one!).
If the calico coloration is combined with a tabby pattern, the cat is called a “caliby.” A tortoiseshell cat that has tabby striping may be called a “torbie,” while cats that are mostly tortoiseshell, but have a smattering of white, are often called “torticos.”
Tortoiseshells got their name because their coloration reminded people of the colorful shell of a real tortoise, a material that was once used to create a variety of household items, including combs and jewelry.
Are calicos a breed of cat?
Calico and tortoiseshell are just words that describe a cat’s coloration. They are not separate breeds of cat. In fact, calico coloring is not something that can easily be bred for, which I’ll explain in more detail below.
Many formal cat breed standards do allow calico coloration, including:
- Manx cat
- American shorthair
- Maine Coon
- British Shorthair
- Persian cat
- Arabian Mau
- Japanese Bobtail
- Exotic Shorthair
- Turkish Van
- Turkish Angora
- Norwegian Forest cat
How do calicos and tortoiseshell cats get their coloring?
Let’s start with a short high-school biology lesson.
Cats, like humans, have little packages of genes inside every single cell in their bodies. These little packages are called chromosomes, and the genes they contain determine many of our traits, from our sex to our eye color.
In cats and humans, chromosomes come in pairs: we get one from each of our parents to make a set.
Like us, a cat’s sex is determined by one of these chromosome pairs. If a cat is female, she will have what is described as two “X” chromosomes. In other words, her mother gave her an “X” and so did her father.
If a cat is male, he will generally have what is described as an “XY” pair of chromosomes. He got an X from his mom, because females only have Xs to give, and he got a Y from his dad, because males can contribute either an X or a Y.
What do Xs and Ys have to do with calico cats?
Calico coloring is considered a “sex-linked” trait. What does that mean? It means that the genes for this trait happen to be in the same chromosome bundle as the genes that determine whether a cat is male or female.
In the case of calico and tortoiseshell cats, the genes that are responsible for their outrageous coloring are on the X chromosome. It takes two “Xs” to get calico or tortoiseshell coloring. Thus, with some rare exceptions (more on that below), only female cats can be calicos or tortoiseshells. Remember, females have two “Xs” while males have only one.
How do the calico genes work?
Actually, there aren’t “calico” genes, which is why breeders can’t breed for the trait.
There are genes that code for either orange fur OR black fur on the X chromosome. This is true of every cat, not just calicos or tortoiseshells.
We already know that a female cat gets two Xs, so she could end up with two orange genes, two black genes, or one of each. If she gets orange genes from both of her parents, she will be an orange cat. A female cat needs to inherit an orange gene from her mother and her father to be orange.
Male cats, on the other hand, only have one X, which they get from their mothers. If that X has a gene that codes for orange fur, the boy cat will have orange fur. In fact, 80% of ginger cats are male.
Back to the girls for a moment. Here’s the problem: a female kitten may get a black gene and an orange gene from her parents, but her body’s cells don’t allow both to be active at once.
While a kitten is still an embryo, growing in her mother’s uterus, one of the genes in every cell will deactivate. This is called “lyonization.” Lyonization is random, and there’s no way to predict whether black or orange will deactivate. But all the cells don’t “agree” on which one to deactivate, which is why, when a calico or tortoiseshell kitten is born, she will have patches of both colors.
What about white?
Calico cats, unlike tortoiseshells, also have white patches. The white is caused by a completely different set of genes.
There are actually three ways in which a cat ends up with white fur.
Why do some calicos have a lot of white fur, and some have just a little?
It’s believed that a cat with white spots that cover at least half of her body, inherited the white-spotting gene from both parents. If a calico cat inherited the gene from only one parent, it’s likely she’ll have white on smaller areas, like the feet, nose, chest, and belly.
If a cat doesn’t inherit the white-spotting gene at all, she’ll be a tortoiseshell.
What causes a calico to have large patches of color versus small patches?
Some calico cats have big patches of color and some have smaller patches. Tortoiseshell cats usually only have small patches, or even a kind of salt-and-pepper look to their fur.
There seems to be a couple of factors that affect the size and number of patches on a calico cat.
If the calico has a lot of white fur (because she inherited the white-spotting gene from both parents), she will likely have fewer patches all together, and they will all be larger.
It is also believed that larger patches happen if the lyonization process happens earlier in a kitten’s development in the womb. When lyonization occurs earlier in development, there are fewer cells all the way around. Being lyonized means they've already decided whether they will be black or orange. So, any cells that divide from those already-decided cells will be the same color. Thus, bigger patches of orange, or bigger patches of black.
Are there any male calico or tortoiseshell cats?
I’ve explained that it takes two X chromosomes to be a calico or tortoiseshell. And male cats typically have only one X chromosome.
And yet, according to a study out of the University of Missouri’s College of Veterinary medicine, one out of every 3,000 calico cats is male. How does that happen?
There are three possible ways to end up with a male calico cat.
Most male calicos and tortoiseshells are chimeras
Most commonly, a calico or tortoiseshell male cat is a chimera. A chimera is a person or animal that has cells containing DNA from two different individuals.
This can happen when two kitten embryos fuse together in the womb. If a female embryo fuses with a male embryo, the kitten would have XX/XY chromosomes. He might have tissues that are genetically male, and may appear to be male, but he would have enough “Xs” in some cells to allow him to end up as a calico or tortoiseshell.
Similarly, if two male embryos fuse, the resulting kitten would have XY/XY chromosomes. An XY/XY chimera might have a mix of colors simply because different parts of his skin would originate from different fertilized eggs!
Some male calicos have Klinefelter syndrome
Klinefelter syndrome is a genetic disorder that occurs in cats, humans, and other species, in which males end up with XXY chromosomes. Some individuals actually have a mix of tissues with XX and XY cells jumbled in.
Unfortunately, a cat with Klinefelter syndrome is usually sterile and might have other health issues related to the disorder.
Rarely, a male calico is just a spontaneous mutation
Most rarely, skin cells in a developing kitten spontaneously mutate, resulting in calico or tortoiseshell coloring.
Do calicos and tortoiseshell cats behave differently than other cats?
Ask anyone who has ever had a calico cat, or a tortoiseshell, and they’ll assure you that their cats were not like any other cat that they’ve ever owned. “Aloof,” and “intolerant” are words sometimes used to describe calicos. Also sassy or spunky, temperamental and strong willed. Tortoiseshells are said to have “tortitude,” an all-in-one word for stubbornness, independence, and unpredictability.
Even famed veterinarian Dr. Marty Becker, when asked about the calico personality said, “…a great many cat lovers – and I include veterinarians among them – hold a suspicion that there’s a connection between color and temperament.”
But is it true? Are cats with calico or tortoiseshell coloring really feistier than cats with other coat colors?
In other animals, there is a link between appearance and behavior
It’s not a new idea, that an animal’s behavior could have something to do with its coloring or appearance. In the 1950s, a researcher in Russia bred silver foxes for friendliness, and as his foxes became tamer, their appearance changed, too. Their coat color and ear and tail shapes changed along with their personalities.
Researchers have studied many other animals in search of a link between appearance and personality: minks, Norway rats, English cocker spaniels, Korean Jindos, and Labrador retrievers, among them. There is definitely a connection between coat color and friendly or aggressive behavior in certain animal species.
So, it would not be too far-fetched to think that calicos and tortoiseshells may have personality traits that other cats do not have.
What does science say about the personality of calico and tortoiseshell cats?
So far, there have only been a few casual studies on calico/tortoiseshell personality, and all were based on surveys, not observational science.
In 2012, a researcher at the University of California, Berkeley surveyed 189 cat owners and found that they were more likely to assign positive personality traits to orange cats and less favorable ones to white and tortoiseshell cats.
This study was a follow-on to previous research on “black-cat syndrome” where brown and black cats were less likely to be adopted than cats of other colors. In that study, black cats, white cats, and tri-color cats were deemed to be more antisocial than other cats. As we now know, perception about cat color has a devastating impact on adoption rates at animal shelters.
But is it true?
In 2016, researchers at UC Davis set out to discover whether cats of any particular coat color or pattern were more likely to be aggressive toward humans in certain circumstances, including petting, grooming, and vet visits. They surveyed 1,274 cat owners.
The results were interesting. Tortoiseshell, calico, and torbie cats were rated as more frequently aggressive toward humans, but so were black-and white cats, and gray-and-white cats.
Researchers said that the differences between all the cat colors were relatively small and could be potentially explained by how cat guardians interpreted the scoring criteria.
In other words, if there were any differences, the differences were minor and could be explained by other factors, including the fact that they were not based on objective, scientific observation.
But the media went wild with the story. People Magazine said, “Study Shows Link Between Cat’s Fur Color and Aggression Level,” adding this subtitle: “Based on the results, calico cats are linked to the highest aggression levels.”
The Independent, a British online newspaper, reported, “A cat’s level of aggressiveness could depend on its color, say scientists,” with this subtitle: “Tortoiseshell-and-white females have a mean streak.”
The Pittsburgh Post-Gazette, reposting a story originally published in the Sacramento Bee, said “UC Davis study: Calico, tortoiseshell female cats often most challenging.”
I think biases against calico and tortoiseshell cats run pretty deep, and they're not necessarily based in fact. What do you think?
My favorite calico cat story
In 2007 a stray calico cat named Tama was officially named “Stationmaster of Kishi Station” in Japan’s Wakayam prefecture. Tama was given a stationmaster’s hat and her salary was paid in cat food.
In her first year on the job, ticket sales rose 10%, which was thrilling because the station had previously suffered financial problems and was intended for closure. Tama received a special cat toy and a slice of crab, fed to her by the company president.
Eventually, a Tama-themed train was introduced. It’s decorated with paw prints and cartoon drawings of Tama, and the front of train has cat ears and whiskers. A recording of Tama meowing is played when the doors open at a train station.
Tama died in 2015 at the age of 16. Thousands of her fans attended her funeral. She now has the title of “Honorable Eternal Stationmaster” and was elevated to goddess of the Yakayama Electric Railway in keeping with the Japanese Shinto religion.
Nitama (which means “Tama Two”) now serves as stationmaster.
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 Rettner, Rachael. “3 Human Chimeras That Already Exist.” Scientific American, Scientific American, 8 Aug. 2016, www.scientificamerican.com/article/3-human-chimeras-that-already-exist/.
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 “A Cat's Level of Aggressiveness 'Could Depend on Its Colour'.” The Independent, Independent Digital News and Media, 24 Oct. 2015, www.independent.co.uk/climate-change/news/a-cat-s-level-of-aggressiveness-could-depend-on-its-colour-say-scientists-a6707731.html.
 Hubert, Cynthia. “UC Davis Study: Calico, Tortoiseshell Female Cats Often Most Challenging.” Gazette, 30 Dec. 2015, www.post-gazette.com/pets/pet-reports/2015/12/30/UC-Davis-study-Calico-tortoiseshell-female-cats-often-most-challenging/stories/201512300190.
 Church, Larissa. “Calico Cat Facts to Know - Calico Cat Facts to Know.” Cat Town, Cat Town, 24 May 2021, www.cattownoakland.org/cat-town-blog/2021/04/calico-cat-facts-to-know.