How Exotic Shrub Berries Alter Plumage of Birds

Consumption of the berries of two introduced species of bush honeysuckles, the Morrow’s (Lonicera morrowii) and Tatarian (L. tatarica) honeysuckles, has for the last several decades been altering the plumage coloration of birds of several species in North America. A carotenoid pigment of deep red hue, rhodoxanthin, present in the shrubs’ berries can substitute for yellow carotenoids naturally present in brightly colored (yellow to red) or green feathers if it is ingested at the time of feather molt, resulting in erythristic individuals with reddish tones. Avian species affected by the honeysuckles include not only birds that feed predominantly on fruits, but also insectivorous species that incorporate fruits in their diets at the time of the fall pre-Basic molt. But what are the consequences for the birds?

Presented by: Jocelyn Hudon, Ph.D., Curator of Ornithology, Royal Alberta Museum