Cardinals are so iconic of the United States that they are the state bird of Illinois, Indiana, Kentucky, North Carolina, Ohio, Virginia, and West Virginia. These bright red birds live predominantly in the eastern half of the country, with a range extending down into the eastern portion of Mexico. The brilliant red plumage of the males of this species are hard to miss — especially in the winter, when you’ll see them out in the snow, frolicking at your feeders.
So what is it that makes these beautiful birds so red? And what can you do to help them keep their feathers vibrant and bright?
Why Are Cardinals Red?
If you’ve ever watched cardinals at play, then you’ve probably noticed that it is only the males that are bright red. Female birds tend to be a bit more drab — reddish, but more brown. This is because males of this species use their coloration to attract mates, with the reddest of birds having a higher success rate.
The coloration in these birds comes from three naturally occurring chemical compounds: melanin, porphyrins, and carotenoids. Melanin is present in humans, giving us our skin, hair and eye colors — and it’s what gives cardinals black, brown, and buff hues. Porphyrin is responsible for reddish and brownish shades. But it’s the carotenoids, which create yellow, orange, and red colors, that are perhaps the most important to the male cardinal’s bright red coloring.
These are known as biochrome pigments. If you look at a cross section of the colorful parts of a feather, you’ll see that barbs — the thin, hair-like parts that grow out of the feather’s shaft — have several layers to them. The innermost layer is the core, followed by a middle layer called the cloudy zone, and then the outer layer called the cortex. In cardinals, the carotenoids are deposited in the cortex of each barb. In other words, the coloration is on the surface of cardinal feathers, not within the deeper layers.
Cardinals Love Carotenoid-Rich Foods
All of that bright red coloring has to come from somewhere, right? In cardinals, the color mostly comes from foods rich in carotenoids. In fact, without foods packed with carotenoids, cardinals are normally much less brilliantly colored. Cardinals that are especially bright red are most likely dining on a healthy diet of carotenoid-rich fruits and berries.
If you’d like to help cardinals keep their color, there are several plants that you can grow right in your own backyard.
First, cardinals love native fruit (and many native fruits are packed with the carotenoids these birds need). Keep wild grapes, raspberries, or even an apple tree if you like. Dogwood berries are by far and away the most popular treat among cardinals everywhere. These trees generally flower in white, although they do come in a few shades of pink and purple, but the red berries that these trees produce in the fall will keep the cardinals coming back for more.
If you want to put out birdseed, try black oil sunflower seed, particularly during the winter since cardinals tend to forage for bugs and other high-protein snacks in the summer. Sunflower seeds also provide birds with extra oils and fats that they need to stay healthy throughout the year. You can also mix in some safflower seeds, another source of carotenoids, if you prefer to offer birds a variety of foods.
If you live in an area populated by cardinals then by offering them the foods that they crave, you’ll be inviting them to your yard while keeping them bright, happy, and healthy.