Colorado rescue discovers rare male calico 'unicorn' kitten

April 25 (UPI) -- An animal rescue group said one of its volunteers is currently caring for a male calico kitten, a feline so rare they are often called "unicorn" kittens.

NoCo Kitties in Loveland said the kitten and his siblings were born in a Weld County shed and were turned over to the Weld County Humane Society before coming to NoCo Kitties.

Volunteer Alli Magish, who is fostering the three kittens and their mother, Amber, said she started to suspect one of the three calicos might be male, and a veterinarian confirmed it.

Only one in 3,000 calico kittens are born male, veterinarians said. Calicos typically end up with the coloration due to getting different color genes from the X chromosomes they receive from their parents. Male kittens usually only have one X and one Y chromosomes, but can sometimes end up with calico coloring when they receive XXY chromosomes.

Experts said male calicos can also be the result of chimerism, which involves some cells in an individual's body having XX chromosomes and others having XY chromosomes.

The coloring can also result from random mutations of skin cells, but that is the rarest cause of calico color in males, experts said.

NoCo Kitties said the kitten, dubbed Charlie the Unicorn, will eventually be made available for adoption.