Red feathers on Yellow-shafted Flickers caused by eating honeysuckle

What is it about?

The origin of red wing and tail feathers in Northern Flickers in eastern North America (where they are typically yellow) has puzzled researchers. As the feathers of this species are red in western North American, it was often thought to be genetic in origin. This paper explains that a pigment found in some introduced shrub honeysuckles, when ingested by the birds during feather growth, can result in this color variation.

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Why is it important?

Red feathers in eastern flickers has served as one line of evidence that the western "Red-shafted" Flicker and the eastern "Yellow-shafted" are the same species, but our findings indicate they are more genetically distinct than previously believed. Further, this same phenomena has already been confirmed as the cause for plumage alteration in other bird species. As plumage color or intensity can serve as a signal of fitness to potential mates, there may be consequences to mate choice.