Catherine Reddick simply glanced at her back yard. Reddick is a radiation therapist. She’s also a bird aficionado, or what we affectionately call ourselves, a bird nerd.
She lives with her family in Harriman. At 9:22 a.m. Dec. 4, 2022, she looked out at their bird feeders and saw something unexpected: a yellow male cardinal. At the time she had no idea how rare he was, but he didn’t simply vanish. Cardinals are loyal to a food source. The saffron cardinal turned up at 4 p.m. Dec. 26 and appeared again on New Years Day and Jan. 2.
“I did see him on Jan. 5 in the evening on the ground in my neighbor’s yard by some shrubs,” Reddick noted. Then on Jan. 8, she reported that two other yellow cardinals had been reported in Roane County.
How rare is rare?
A northern cardinal is seen here in a photograph from the Tennessee Aquarium.
Northern cardinals are found from the East Coast to the Rockies. Although some estimate there may be as many as 12 to 15 yellow ones at any given time throughout their range, there is only a handful of documented reports.
The yellow ones apparently are a fresh occurrence in our new millennium. Documentation appears to begin in the early 2000s with a yellow cardinal seen for six years in Louisville, Mississippi. He was also observed helping feed young nestlings that had normal coloration.
Nicholas Winstead with the Mississippi Museum of Natural History reports other sighting locations and dates:
Ohio in 2013. Illinois in 2010 and 2013. Kentucky in 2011. Iowa in 2013. Missouri in 2014. We can also add: Alabama in 2018. Georgia in 2018. Kingston, Tennessee in 2019. Gainesville, Florida in 2022.
Now in Harriman in 2022 into 2023.
There’s a genetic mutation at play here, and it appears to be found only in the males. Cardinals need to eat seeds or fruits like elderberries, blueberries, mulberries and fall native grapes that contain pigment molecules called yellow carotenoids, mainly yellow, orange or red fat-soluble pigments that include carotene. These pigments also give color to plants, like the red of ripe berries.
With male cardinals, the more fruits eaten the more colorful the plumage, and female cardinals tend to choose the brightest red males available because not only are they attractive ... they are the healthiest.
Traditional male cardinals change these pigments from yellow to red and deposit the more oxidized red forms into growing feathers. Apparently the new yellow cardinals cannot make that switch. More research is needed but the study subjects are few and far between.
Questions
This is where it gets interesting.
Northern cardinals tend to mate for life or at least several years. They don’t typically migrate, so the cardinals in your back yard stay relatively close as long as they can find food all year.
Mutations are essential to evolution; they are the raw mechanism that drives genetic variation and the greater the variation the healthier the species.
Genetic variation helps the species adapt to a changing environment. So why is this mutation popping up in so many dispersed locations in just the past two decades?
Could there be an environmental factor driving the change? Will we begin to see future male cardinals with two morphologies, two looks? White-throated sparrows have two morphs. They are the same species but they look and act differently.
Will the yellow morph cardinal isolate and lead to a new sub-species?
Female choice in mates drives the intense coloration in the males. If the females are attracted to the new look, we will start seeing more of them. Are we witnessing evolution at work?
