Looking out at her quaint Alabama backyard in late January, Charlie Stephenson noticed something unusual. A strange species of unfamiliar yellow bird was pecking at her hanging birdfeeder.

As a seasoned birdwatcher, Stephenson had seen scores of cardinals in the past. But with its mustard-color coat, this flier was different. So, she took a photo with her iPhone and posted it on Facebook.

Stephenson told AL.com she has seen albino and leucistic birds, the latter being animals that are mostly white but can produce some pigment. (Related: "Why Yellow Birds Mysteriously Turn Red.")

But this golden visitor is neither: it's a male northern cardinal with a "one in a million" genetic mutation that made its red feathers yellow,