A look into how what a bird eats can affect it color, with a spotlight on the Cedar Waxwing

If you see a flock of Cedar Waxwings, you may notice that some have yellow tipped tails while others may be orange. That color change is a direct result of something relatively new being included in their diet.

When a waxwing’s tail feathers grow in, they are typically a bright yellow, but when the tail is growing in and they eat berries from the honeysuckle plant, an introduced invasive plant that produces a high yield of dark red berries, their tail feathers will grow in at varying levels of orange. This is because these berries contain high concentrations of carotenoid pigments and when ingested, get deposited in their feathers. Carotenoids are one of the four different pigments that make up a feathers color, creating shades of yellow, orange and red. This pigment cannot be created though, it must be ingested, generally getting this pigment from the fruit, berries, and seeds they eat.

These berries become ripe around the same time that Cedar Waxwings are nesting, because of this the young end up being fed a high percentage of these berries, resulting in most of the young growing in orange-tipped tails. Though, later in the season when they molt again but don’t have access to the berries of the honeysuckle, their new tails feathers grow back in with the typical bright yellow tips. So, when you see a Cedar Waxwing with an orange or red tail, it is most likely an individual that hatched that year.

Another backyard bird that this change can be seen in is the Northern Cardinal. Their color is even impacted by the same plant as the Cedar Waxwing. Males who feed on a large percentage of the honeysuckle berries grow in feathers that are a much more vibrant red than ones that have a more varied diet.

Unfortunately, the berries from the honeysuckle plant are not as nutritious, so while male cardinals that eat them can be a more vivid red and may appear as a better mate from a female's perspective, studies have shown that these same males typically weight less and are probably not as healthy as males who have not included as many of the berries in their diet and are not as vividly colored.

Another backyard bird's whos color can be affected by what's included in their diet is the House Finch, the males can have varying shades of red depending on the percentage of berries they eat.

An additional drastic example of diet affecting a bird's color can be seen in flamingos. These birds' diet consists of krill, brine shrimp and other invertebrates, who in turn, feed on algae high in carotenoids. As the carotenoids in algae goes up the food chain, the concentration of this pigment increases, resulting in the pink you see in the brine shrimp and krill, and in the bright pink you see in the plumage of flamingos. In captivity, where flamingos may not naturally have access to this pigment, their feathers would be gray or a very pale pink. To recreate this coloration, zoos feed their flamingos a special diet containing synthetic canthaxanthin to achieve this pink color.