Update: David Bowie has been adopted, according to the Humane Society of St. Joseph County.

Original story:

David Bowie is a unicorn.

Or he may as well be, since he's just about as rare.

The newest kitty waiting for a forever home at the Humane Society of St. Joseph County is extremely rare: a male with a calico fur pattern. He is about 4 years old and is affectionate, outgoing, front declawed and gets along with the other cats in the shelter, said Genny Carlson, the executive director of the shelter.

But what stands out most about David Bowie is his sex.

"Have any of you ever seen a male calico cat? Most of us haven’t either!" the shelter wrote Friday in a Facebook post.

The shelter used a commonly cited statistic saying one in 3,000 calicos are male. While it's hard to pin down that number, everyone agrees David Bowie is a rare cat.

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The calico fur pattern is predominantly white, with patches of two other colors — in David Bowie's case, orange and black. And because a cat's fur color is linked to its cells' X chromosomes, calico cats are rarely male. Male cells have only one X chromosome, meaning normally, males are just one color.

However, there are three ways in which a male cat can have a calico fur pattern, said Kari Ekenstedt, an assistant professor of anatomy and genetics in Purdue University's College of Veterinary Medicine.

First, a male cat's cells could have two X chromosomes, as opposed to just one. And if each cell's two X chromosomes carried a different fur color, it would be easy to explain how a male cat could have both an orange and black fur pattern, Ekenstedt said.

Another way, Ekenstedt said, is through the mutation of X chromosomes in a male cat's cells. For example, Ekenstedt said, a male cat's cells could carry X chromosomes that would make it black. But while the embryo is developing, Ekenstedt said, one X chromosome could mutate and switch to a new color. This could cause the X chromosomes in other cells to also mutate, giving the cat a mix of both colors.

Ekenstedt said she suspects this is the most common way male cats with the calico fur pattern are created.

"Even though, when I say common, it's vanishingly rare that we ever see them," she said.

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The third possibility, Ekenstedt said, is that a male calico could actually be a chimera. This would mean the cat has a mixture of XX and XY cells. This happens when two different embryos merge together, Ekenstedt said.

Without conducting tests, there is no way to know how David Bowie became calico-colored. Male calicos are often sterile, Ekenstedt said, but because David Bowie has been neutered, that does not matter.

Ekenstedt said other than causing possible infertility, calico patterns do not affect a male cat's health.

"There's no reason he shouldn't live a nice, long, healthy life," Ekenstedt said.

David Bowie's adoption fee is $50, Carlson said. Anyone interested must fill out an application on the Humane Society of St. Joseph County's website. On the form, you may list David Bowie as the pet you are interested in adopting.

You may also need to consult with an adoption specialist at the shelter before you may take David Bowie home, Carlson said.

As of Friday, the shelter has 100 total cats available to adopt, Carlson said.

Andrew Clark is Facebook editor for IndyStar. Call him at 317-444-6484 or email him at andrew.clark@indystar.com. Follow him on Twitter @Clarky_Tweets.