Third in a series
By Anders Gyllenhaal
The first time we came across one of the elaborate feeding stations common in South America, we were astounded by something you otherwise never see: The sight of deep blue tanagers perched right next to golden warblers alongside yellow toucans, green parrots and black-and-red woodpeckers.
I keep thinking about that rainbow of hues in exploring one of the most intriguing questions people ask about birds. Why are they dressed from beak to tail in the most dramatic and varied colors in nature?
The answer is both simple and intriguingly complex.
When I asked Kevin McGowan, the plain-spoken scientist at the Cornell Lab of Ornithology, he laughed and began with the easy part. “It’s about sex,’’ he said. Indeed, we’ve known since Charles Darwin’s historic research that birds choose mates partly on their plumage.
But that’s just the beginning of a story that has turned into one of the frontiers of avian research. Recent discoveries using DNA, databases and sophisticated microscopes are uncovering the surprising ways that colors work in the bird world – and how those colors have turned brighter and more elaborate over millions of years.
Big questions about birds
This post is part of our series taking up the most frequent questions people have about birds, based on Google searches and queries to AI sites from Gemini to ChatGPT (see details below). So far we’ve dug into the mysteries of flight, and whether birds have actual consciousness. In both of those posts, the answers have been made far more compelling by the latest research and technologies that are tracking and dissecting birds as never before.
Visual creatures
That is very much the case with birds and their colors: Scientists are delivering new revelations about how they create colors in often the most innovative ways. How they sometimes cheat to get the brightest tones. How the structures of feathers can reflect colors that aren’t actually there. And how birds use their plumage to show their health, smarts, fighting prowess and – yes – potential as mates.
And just as Darwin pieced together the theory of evolution in part by watching birds, modern avian researchers are studying birds to figure out how genetics are passed down lineages and how some colors are formed deep in the microscopic roots of feathers.
“It’s amazing how the whole color structure works,’’ said Allison Shultz, an ornithologist and evolutionary scientist at Los Angeles’ Natural History Museum and a leading expert in colors, plumage and feathers. “What really gets me excited is thinking about what produces that color.’’
Colors we can’t even see
It’s tempting to think birds and their beauty are part of nature’s gift to humans. But the fact is we can’t even see the breadth of colors visible to birds themselves. That’s because birds are equipped with expanded vision that enables them to see extra colors that include ultraviolet hues and other wavelengths of light invisible to us.
Why would birds alone have this hyper-eyesight? It’s because visuals are so important in the world of birds that their colors have blossomed over time with evolution to serve their many purposes. “With mammals, the main sense is smell,’’ Cornell’s McGowan explained. “But with birds, the main sense is sight. They’re visual animals.”
In one intriguing example, researchers set up a test of European Starlings, which look drab to humans but appear far more colorful to fellow birds with their ultraviolet colors visible. Female starlings rated males much higher when the UV light was on display — as if they were seeing completely different birds.
How birds make colors
The most fascinating part of bird coloration, as it’s called, is the various ways bird create the shades of their plumage.
Some colors – including reds, oranges, yellows — are produced by pigments consumed in their diets and deposited n their feathers. Other colors are created by microscopic arrangements within the feathers that manipulate light. Some of the most spectacular colors are the result of a combination of the two methods working together.
So it gets complicated – but that’s part of what delights scientists and propels the science of coloration. “Essentially, it’s because feathers themselves are so intricate and so complex,’’ said Shultz, whose work is enriched by a collection of 121,000 specimens that enable the study of feathers, birds’ eyes and wing structures gathered since the late 1800s.
Cheating on mates
One of Shultz’ most storied discoveries is how some male tanagers highlight their red, yellow and orange hues to fool females they hope to attract as mates.
Those colors are usually produced by the hard work of consuming plants that color feathers. But these tanagers don’t rely on that work alone. They’ve developed unusual feather structures that amplify their tones, making them appear more colorful than they are.
As the museum’s headline put it in announcing the findings: “Fake it til you make it: How tropical tanagers cheat their way to flashier feathers and hopefully more mates.”
Looking backward
Scientists are able to make these advances with the help of sophisticated research methods, including genetics, high-powered cameras and spectrophotometers (that capture hidden wavelengths of light.) The tools enable scientists like Shultz to look not only at how current colors are created, but how they’ve evolved over the 100 millions years since the first birds emerged in the dinosaur era.
“That’s where some really interesting things are going on,’’ she said. “Looking backwards to how it got that way.’’
A good illustration comes from ongoing research at a Penn State University biology lab showing how hybridization — mating between closely related species — can move color genes from one group of birds to another. This showed that birds don’t necessarily have to wait for useful traits and colors to evolve painstakingly over thousands and millions of years — in effect dramatically speeding genetic change.
To pull off this research, the latest study of which was published in PLOS Biology in 2025, the lab traced the genomes of some 500 birds from 100 species to reconstruct their evolutionary histories. This opened a new window in evolutionary theory, by allowing them to map how colors can be swapped among these birds.
“It turns out that some of these birds may have borrowed colors from their neighbors rather than evolving them independently,’’ the lab’s director, Dave Toews, said in Penn State’s announcement of the discovery. “That means some genetic funny business was going on in these warblers millions of years ago.’’
What this might mean
These discoveries are changing the understanding of the raw materials evolution has to work with. If desirable genetic variations can move between species in ways never known before, that in turn raises new questions.
One is a particularly urgent question today: Do birds have enough genetic variation — and can evolution act on it quickly enough — to keep pace with changing environments.
“We typically thought of evolution as needing thousands or millions of years,’’ said Shultz. “But actually we can see evolution just over the matter of a handful of years. So I think the big question is does variation within a population experiencing rapid change allow them to actually survive and evolve in time.’’
What’s ahead
So researchers have figured out a great deal about why birds hold this remarkable franchise on color? A potent combination of conditions are at work: Species that depend heavily on vision happened to be covered from head to tail in feathers capable of creating colors in remarkably different ways. Over millions of years of judging one another by what they see, birds with the most impressive colors win out — which then spreads those traits down their lineages.
But the more scientists learn, the more they realize how much is still unknown about all of this. The biggest questions have to do with the detailed mechanics of color creation and what the science of colors says about genetics.
A major review of bird-color research published this summer put the challenge succinctly: “The rapid growth of avian genomic resources has created a field rich in genomic data but still in need of integrative synthesis,” the study began. In other words, scientists are accumulating huge amounts of information about the genes and structures behind bird colors. But there’s still plenty of work to do.
Given how complex birds’ color creation is, are there ways of creating and shaping colors that scientists have yet to discover? Researchers found that the Great Argus, a decorative Asian pheasant, creates a blue color from the tiniest wrinkle in the shaft of its flight feathers — a method never documented before. If scientists can discover a completely new color-making mechanism in a well-known bird, what remains hidden among the roughly 11,000 other species in the world?
How birds see things
Another rich area for discovery is the unique vision that birds possess and how this plays out in their daily lives.
Shultz and her peers have been able to model what birds are seeing by studying their eyes and testing their reactions to various colors.
“But there are missing pieces,’’ she said. “There’s a lot we don’t know about the pathways in the brain and how all this combines. We know the end results. Can birds detect differences we don’t see? The answer is yes. But we don’t really know all that’s in between. It’s fun to think about.’’
Up next: The next two posts in “What We’re Learning from the Birds” will look at how birds developed their remarkable singing talents and how birds are adapting in a changing environment. Why do they wake up and launch right into what’s called the “dawn chorus?” What accounts for their sometimes vast collection of tunes, whistles, chirrps and tics? On a very different front, how are birds and their versatility confronting the changing environment? In what ways are they are adapting, and where are they unable to adapt? What impact is this having on migration, reproduction, food sources and population trends? These are vital questions when it comes to the future of birds. Watch for these posts in the coming weeks.
What are the top questions people have about birds?
People have had many of the same questions about birds for generations. But today, the answers are changing — sometimes dramatically — as researchers have gained the tools to track birds in flight, peer into their DNA and use powerful new technologies to watch them in action.
This is the one of the primary reasons we’ve pulled together the most intriguing, age-old questions and delved into the modern avian sciences to answer them. Another reason is that the number of people — old and young — now interested in birds has exploded since the pandemic — and with that come all sorts of questions.
We’ve drawn the top questions from two sources: the most common bird queries people ask search engines like Google and Bing, and the deeper, more open-ended questions increasingly posed to AI systems such as ChatGPT, Claude and Gemini.
These posts explore these questions through the lens of Flying Lessons — looking not only at the astonishing abilities birds possess, but at what we’re learning from them. The answers seek to reach beyond anatomy and instinct into such subjects as intelligence, evolution, navigation, communication, memory and consciousness.
Taken together, we think ongoing discoveries reveal something important: The more we learn about birds, the more mysterious and remarkable we realize they are.
We’d love to hear your own questions — and your thoughts on these answers — as we explore mysteries and latest revelations about birds. Here are some of the questions we’ll be answering in the coming months (with links to the ones we’ve finished.)
How do birds fly the way they do?
What goes on inside a bird’s head? Do birds have consciousness?
Why are birds so colorful — matched by no other segment of nature?
Why do they sing — especially at dawn?
How well are birds adapting to the rapidly changing environment — and what does this mean for their future?
What can be done to help birds in an era of change, pressure on populations and powerful new conservation tools?
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