Do fruits bearing the red carotenoid rhodoxanthin affect avian plumage coloration in Japan

Consumption of the berries of Morrow's Honeysuckle Lonicera morrowii has caused reddening of bird plumages in North America. We looked for examples of reddened feathers in Japanese birds, where the honeysuckle is native. We report the observation of legitimate reddened feathers in three Gray-headed Woodpeckers Picus canus, but are unsure whether the honeysuckle caused the color change in this instance. Morrow's Honeysuckle is uncommon in Japan, and birds rarely eat its berries. The availability of a wide variety of edible fruits may generally reduce the likelihood of avian plumage coloration being altered by shrubs such as the honeysuckle in Japan.