Chemistry of Birds

The Chemistry of Birds (24): Turning Pink

December 14, 2025 by Kai Pflug No Comments

If you are worried about, or hoping for, a post with an LGBT topic: No, this is about flamingos. And the chemistry behind their color.

Flamingoes get their color from their food, but then also convert some of the relevant substances before depositing them in their feathers.

The reddish-pink color of marine organisms such as freshwater algae, shrimp, lobster, and salmon mainly comes from astaxanthin.

Astaxanthin

Flamingos eat algae and brine shrimp, thus taking up astaxanthin. Then, some of this astaxanthin is converted into a similar molecule, canthaxanthin, in their livers, in a reaction that chemically can be described as a reductive dehydroxylation (the hydroxyl groups at two carbon atoms are converted into hydrogen). This is catalyzed by carotenoid dehydrogenases/oxidases.

Canthaxanthin

The canthaxanthin is then deposited into the feathers of the flamingos, which is the main contributor to the pink color of most flamingo species.

Here are a few more mildly relevant facts related to flamingos and their colors:

  • If you are a flamingo yourself and are looking for a partner, choose one with a strong pink color – this indicates your mate is good at foraging.
  • As the color requires the right food (i.e., containing carotenoids), flamingos without access to this food do not have pink feathers. This can happen in zoos (though zookeepers sometimes feed them astaxanthin directly to justify the ticket prices – visitors would be unhappy to just see grey flamingoes).
  • Also, I guess that this flamingo seen in Shanghai in the wild in winter did not get many carotenoids in its diet.

Finally, two completely irrelevant facts (aren’t those sometimes the most interesting?):

  • Given its importance for flamingos, the University of Bristol named astaxanthin as the “Molecule of the Month” in June 2021. Unfortunately, the acceptance speech was not recorded
  • And design company Figma points out that “Flamingo pink is a vibrant, warm hue sitting between pink and orange on the color wheel. This lively shade evokes feelings of playfulness and joy, similar to soft pinks like salmon and blush. Perfect for designs aiming for a cheerful, inviting atmosphere or playful accents in a pastel palette.”

Sources:

Written by Kai Pflug
Kai has lived in Shanghai for more than 21 years. He only started birding after moving to China, so he is far more familiar with Chinese birds than the ones back in his native Germany. As a birder, he considers himself strictly average and tries to make up for it with photography, which he shares on a separate website. Alas, most of the photos are pretty average as well. He hopes that few clients of his consulting firm—focused on China’s chemical industry—ever find this blog, as it might raise questions about his professional priorities. Much of his time is spent either editing posts for 10,000 Birds or cleaning the litter boxes of his numerous indoor cats. He occasionally considers writing a piece comparing the two activities.