They produce a range of colors, including red, brown, pink, and green. Birds that have this pigment tend to be owls, turacos, pigeons, and grouse.

A version of this article appears in print on Sept. 14, 2024, Section A, Page 1 of the New York edition with the headline: City Birds Lose Colors but Gain A Survival Edge.

Tanagers, like many other birds, owe their red, yellow and orange hues, in part, to a group of pigments known as carotenoids, which they cannot make themselves and must find in the wild.