Apparently, calico and tortoiseshell cats are the feline equivalent of fiery redheads among humans, and maybe not just by reputation.

In a published study, veterinarians from University of California Davis found that cats with those mottled and often beautiful fur patterns tend to challenge their humans more frequently than other cats.

It turns out that veterinarians already had theories on this--many of them thought tortoiseshells and calicos were a bit "difficult," Dr. Elizabeth Stelow, a UC Davis Veterinary Medical Teaching Hospital behavioral expert, said in an article in the Sacramento Bee.

The study itself had its base in a survey of about 1,200 cat owners. The survey was online, posted on a social media site -- and it did not mention the study's focus. The questions asked cat owners about their pet's behaviors, and asked that they choose a written description and color category that fit their feline.

The data suggests that calicos and torties, and especially cats that have gray and white or black and white coats, are a bit more likely to chase, hiss, bite, scratch or swat as they interact with people. The study was published in the Journal of Applied Animal Welfare Science.

To do a quick explainer, a calico is a cat that is mostly white and has patches of black and orange. A tortoiseshell has a wide range of patches in brown, black, red and amber. It takes two X chromosomes to result in such coloring, so nearly all of both calicos and torties are female.

"They're fiery," said animal shelter manager Gina Knepp in the article. "They've got a little spirit and zip to them. If you want a cat that will keep you on your toes, a calico or tortie is the way to go."

Stelow admits that the study had some limitations, such as that researchers did not see the cats themselves but relied on the assessments of owners, but she says that the research results offer findings that warrant a second look. "We thought the findings were very interesting, and we would love other researchers to take the baton and run with it, to look at the genetics of why this may be happening," Stelow said in the article.

That said, Stelow has a calico cat herself, along with an orange tabby, and says both are great companions. She noted too that aggression in cats is rarely violent. "It's very different from dogs. Dogs show a very, very wide range from not aggressive at all to capable of killing. The overwhelming majority of cats are not the least aggressive," and those that are usually show it in "very subtle ways," Stelow said in the article.

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