Hummingbirds see lots of colors that humans can’t

A study uses sugar water experiments to show that hummingbirds can see colors invisible to us.


"Oh wow, the colors!"

Image source: Bonnie Taylor Barry/Shutterstock
  • Hummingbirds can see colors in the ultraviolet range. We cannot.
  • The tiny powerhouse derive hues from four types of photoreceptors, as opposed to our three.
  • As beautiful as the world already is, let's talk about what hummers see.

Do you know what the first three nonspectral colors are? Nope. Neither do we or any other humans. Maybe you should ask a hummingbird. The colors we know are part of the visible spectrum, a series of electromagnetic waves whose lengths are between 380 and 700 nanometers. (Electromagnetic waves repeat, and a wavelength is the distance between one repeat and the next.)

There are electromagnetic waves whose length is shorter or longer, but we lack the ability to see them. There is some evidence that other species can see these wavelengths — most famously the mantis shrimp — and a new study affirms that hummingbirds can indeed detect non-spectral wavelengths, and thus colors. As if these little creatures weren't already amazing enough.

Incredible already

People all over the world exhibit a fascination with the tiny, beautiful avians that are birds unlike any other. Minute yet powerful, these incredible little energy bombs annually migrate great distances, living only on nectar and sugar water during visits to gardens — anyone who's ever annoyed a hummer by changing their food at feeding time can attest that these little buzzing creatures are not shy. Before getting into hummingbirds' remarkable color perception, here are a few other jaw-dropping stats:

  • Hummingbirds can beat their wings from 20 to 200 times per second.
  • If a human were to burn as many calories as a hummingbird, that human would have to consume 155,000 calories per day.
  • Hummingbirds have larger hearts (by body size) than any other bird, which is good because it can beat 12,000 times per minute.
  • The dazzling, iridescent red neck of a male ruby-throated hummingbird is an optical illusion — their chest is actually black, brown, and reddish brown.
flying hummingbird

Tricky ruby throat

Image source: Steve Byland/Shutterstock

So many colors

The new study in Proceedings of the National Academy of Sciences of the United States of America explains why its authors believe hummingbirds can see non-spectral colors.

First, the researchers recruited some volunteers: wild broad-tailed hummingbirds (Selasphorus platycercus). The experiments took place at the Rocky Mountain Biological Laboratory (RMBL) in Colorado, an environment researchers took pains to keep as natural as possible during the three-year study. Scientists from Princeton, the University of British Columbia (UBC), Harvard University, University of Maryland, and RMBL were involved in the experiments.

Before dawn each day, the researchers set up a pair of feeders for the birds — one with a rewarding drink of sugar water, the other with unsweetened plain water. Next to each feeder was an LED tube capable of emitting a broad range of colors, including nonspectral colors. Over the course of several hours, the hummingbirds learned that one color — sometimes a nonspectral color — signified the rewarding tube, and another color the plain water. When the feeders' positions were swapped, the hummingbirds simply followed the color, even if it was one the researchers themselves couldn't discern.

Study co-author Harold Eyster recalls, "It was amazing to watch. The ultraviolet+green light and green light looked identical to us, but the hummingbirds kept correctly choosing the ultraviolet+green light associated with sugar water. Our experiments enabled us to get a sneak peek into what the world looks like to a hummingbird."

The tests were run with various spectral and nonspectral color pairings for the two feeders, and the hummingbirds apparently couldn't have cared less which kind of color was employed — they quickly learned where the sugar-water feeder was. The researchers also ran control experiments to make sure the birds weren't being tipped off by smell or some other cue.

Though the experiment was fundamentally pretty simple, the results are stunning. Lead author Mary Caswell Stoddard of Princeton says, "To imagine an extra dimension of color vision — that is the thrill and challenge of studying how avian perception works."

How hummingbirds do this

Human eyes have three types of color receptors, or cones, each of which responds most strongly to a specific range of wavelengths — S-cones specialize in blue, M-cones green, and L-cones red. From combinations of those three basic hues, our eyes and brains present us the millions of colors we perceive.

Though hummingbirds come nowhere near the mantis shrimp's twelve-plus collection of cone types, they do have four, which endows them with tetrachromacy. If we, with our trichromacy, can construct so many colors from three basic hues, imagine what adding a fourth might do. In the hummingbirds' case, the fourth cone type perceives ultraviolet light that can be added to the other three hues for unimaginable (to us) combinations.

"Humans are color-blind compared to birds and many other animals," points out Stoddard. We can only wonder what these colors actually look like to hummingbirds. As RMBL's David Inouye says, "The colors that we see in the fields of wildflowers at our study site, the wildflower capital of Colorado, are stunning to us, but just imagine what those flowers look like to birds with that extra sensory dimension."

How New York's largest hospital system is predicting COVID-19 spikes

Northwell Health is using insights from website traffic to forecast COVID-19 hospitalizations two weeks in the future.

Credit: Getty Images
Sponsored by Northwell Health
  • The machine-learning algorithm works by analyzing the online behavior of visitors to the Northwell Health website and comparing that data to future COVID-19 hospitalizations.
  • The tool, which uses anonymized data, has so far predicted hospitalizations with an accuracy rate of 80 percent.
  • Machine-learning tools are helping health-care professionals worldwide better constrain and treat COVID-19.
Keep reading Show less

Listen: Scientists re-create voice of 3,000-year-old Egyptian mummy

Scientists used CT scanning and 3D-printing technology to re-create the voice of Nesyamun, an ancient Egyptian priest.

Surprising Science
  • Scientists printed a 3D replica of the vocal tract of Nesyamun, an Egyptian priest whose mummified corpse has been on display in the UK for two centuries.
  • With the help of an electronic device, the reproduced voice is able to "speak" a vowel noise.
  • The team behind the "Voices of the Past" project suggest reproducing ancient voices could make museum experiences more dynamic.
Keep reading Show less

Dark matter axions possibly found near Magnificent 7 neutron stars

A new study proposes mysterious axions may be found in X-rays coming from a cluster of neutron stars.

A rendering of the XMM-Newton (X-ray multi-mirror mission) space telescope.

Credit: D. Ducros; ESA/XMM-Newton, CC BY-SA 3.0 IGO
Surprising Science
  • A study led by Berkeley Lab suggests axions may be present near neutron stars known as the Magnificent Seven.
  • The axions, theorized fundamental particles, could be found in the high-energy X-rays emitted from the stars.
  • Axions have yet to be observed directly and may be responsible for the elusive dark matter.
  • Keep reading Show less

    Put on a happy face? “Deep acting” associated with improved work life

    New research suggests you can't fake your emotional state to improve your work life — you have to feel it.

    Credit: Columbia Pictures
    Personal Growth
  • Deep acting is the work strategy of regulating your emotions to match a desired state.
  • New research suggests that deep acting reduces fatigue, improves trust, and advances goal progress over other regulation strategies.
  • Further research suggests learning to attune our emotions for deep acting is a beneficial work-life strategy.
  • Keep reading Show less
    Surprising Science

    World's oldest work of art found in a hidden Indonesian valley

    Archaeologists discover a cave painting of a wild pig that is now the world's oldest dated work of representational art.

    Scroll down to load more…