You Are What You Eat: Honeysuckle Colors Birds
Birds don’t always look like the photographs you find of them in field guides. I was reminded of this just a few days ago while looking at a flock of Cedar Waxwings. Their placid attitude while feeding on berries made me pause and really watch them. I noticed that a few of them had tails with orange tips rather than the normal bright yellow. My Audubon Guides bird app says “yellow tips (sometimes reddish) on tail feathers”. A look at the both the adult and juvenile photos shows only yellow tips. Why are they sometimes reddish?
You are what you eat. Birds assimilate natural pigments called carotenoids from eating plants. These pigments are fat-soluble substances like vitamin A in carrots from which they take their name. And they just happen to produce red, yellow, or orange feathers.
Orange tails have not been in vogue for many years. The first orange tips were notices about 30 years ago and they have become more and more common. For the past 30 years the frequency of orange waxwing tail tips has been increasing in the Northeast. Orange feathers contain large amounts of the red carotenoid pigment rhodoxanthin not found in normal yellow tail tips. The arrival of orange tail tips corresponds closely with the introduction of two invasive honeysuckle shrubs, Morrow’s Honeysuckle and Tartanian Honeysuckle. Both contain large amounts of rhodoxanthin. The ripe red berries are available in June and July when young waxwings are growing their feathers. Adults don’t molt and grow their feathers until late summer or early fall when the berries are mostly gone, so not many adults have orange tail tips.
It doesn’t just affect waxwings. I have also seen White-throated Sparrows with orange lores rather than yellow and young Veery with red tinted flanks. Eating honeysuckle berries may also account for orange feathers in Yellow-breasted Chat and Kentucky Warblers. Keep your eyes open and let me know if you find any orange where yellow once was the rule.