Northern cardinals are famous for their trademark bright red plumes. This is why there’s no surprise that the unexpected sighting of a yellow cardinal in Alabaster, Alabama, has turned into a full-blown ornithological event. According to AL.com, birdwatchers and biologists have taken the city by storm over the last few days trying to catch a glimpse of the unusual golden songbird.
Stunning images of the incredibly rare yellow cardinal, taken by professional photographer Jeremy Black, have been circling the internet since Monday (February 19). But it was Black’s friend, birdwatcher Charlie Stephenson, who initially spotted the uncommon flier back in late January, National Geographic reports.
“I thought ‘well there’s a bird I’ve never seen before.’ Then I realized it was a cardinal, and it was a yellow cardinal,” Stephenson said in a statement.
The video below, showing the rare yellow cardinal hanging around at a birdfeeder, was taken by Stephenson in her own backyard. Although the seasoned birdwatcher was reluctant to publicize her address for fear of being invaded by bird enthusiasts, she did specify that she resides in the vicinity of the new Thompson High School in Alabaster, AL.com notes.
Biologist Geoffrey Hill, from Auburn University in Alabama, has identified the extremely rare songbird as an adult male northern cardinal — not to be confused with the South American yellow cardinal — and is convinced its unique appearance is most likely due to a genetic mutation.
Hill, who is an ornithologist and coloration expert, believes the bright yellow cardinal photographed in Alabaster may be suffering from xanthochroism, a genetic condition in which the normal red pigments in the bird’s feathers are diluted and replaced by yellow or orange ones.
Hill points out that red-feathered birds typically get their color by ingesting food rich in yellow pigments, called carotenoids. These carotenoids, usually found in orange or yellow foods such as carrots and sweet potatoes, are then biochemically converted into red pigments that go on to adorn the birds’ plumage.
In a 2016 study on the genetic factors that give birds their red coloration, Hill explained that red feather pigmentation is produced by an enzyme called CYP2J19. However, in this particular case, xanthochroism is probably blocking the CYP2J19 enzyme, resulting in the spectacular golden color of the bird’s plumes.
This genetic mutation is so rare that in all the 40 years he’s been studying cardinals, Hill has never gotten the chance to see a yellow cardinal in person. He estimates that each year only about two or three yellow cardinals may turn up at backyard feeding stations across the United States or Canada.
“There are probably a million bird feeding stations in that area so very, very roughly, yellow cardinals are a one in a million mutation,” Hill told AL.com.
Black himself had no idea yellow cardinals even existed until he came across Stephenson’s social media posts of the Alabaster cardinal. In a statement for National Geographic, the photographer confessed he thought “for a second” that the initial images were photoshopped. Stephenson invited her friend to come see the majestic songbird in person and after five hours of observation, Hill managed to capture the yellow cardinal on camera.
The National Audubon Society also published a feature on the Alabaster yellow cardinal and is offering an alternative explanation for the songbird’s golden plumage. Geoff LeBaron, Audubon’s Christmas Bird Count director, indicates the discolored pigments in the cardinal’s feathers can potentially be put down to a poor diet or environmental stressors.
LeBaron doesn’t discard Hill’s theory and actually agrees a rare genetic mutation might be the more likely culprit. However, he points out that the reason behind the northern cardinal’s unusual plumes can be clarified next year after the bird has swapped its feathers. If the cardinal remains in the area and is still yellow next winter, then the xanthochroism hypothesis wins the case, said LeBaron.