Typical flickers are shown at the top: red on the left and yellow on the right. At bottom left is an intergrade, with a uniformly intermediate wing color and intermediate head pattern. In the lower right is an abnormally colored yellow tree, with some red feathers in the wings. Art by David Sibley
The Northern Flicker is a familiar bird in the lower 48 states and southern Canada. Within this wide range, it occurs in two strikingly different forms, long considered separate species: the “Red-tailed Twinkle” in the west and the “Yellow-tailed Twinkle” in the east.
The two forms differ most obviously in the color of the large wing and tail feathers, red or yellow, respectively. They also differ in the pattern of the head. In the middle of the continent, however, the shapes blend together and it is common to see sparkles with an intermediate wing and tail color. Anywhere between the eastern edge of the Rockies and the eastern edge of the Great Plains, you should expect to see shimmers with colors in between. On closer inspection, these birds also exhibit mixed head patterns, confirming their identity as intergrades.
The red and yellow colors in birds are produced by carotenoid pigments. All carotenoids come from the diet of birds and (usually) any difference in color results from a difference in how each population processes these carotenoids to produce pigments. There are variations in color saturation and shade depending on the age, sex, and health of the bird, but in general these red and yellow colors are fairly consistent. With the same regime, an eastern flicker will produce yellow feathers, a western flicker will produce red feathers, and an intergrade flicker will produce orange feathers.
The exception to this rule involves a chemical compound found in the fruit of some Asian honeysuckles, now widespread across much of North America. When birds consume this new compound, it produces a red pigment, even in normally yellow species. This has led to the appearance of Cedar Waxwings with orange tail bands, red-breasted Baltimore Orioles, and more.
These are birds that consumed a few honeysuckle berries while growing new wing feathers and deposited red pigment in the growing feathers. Usually the effect is short-lived and only a few red feathers grow in each wing, which distinguishes this variation from intergrades which have a more uniform color.
No doubt: the story of The Northern Flicker is fascinating!
This article first appeared in the May/June 2020 issue of BirdWatching magazine. Subscribe now.
