All About Feathers

Unique to birds and their dinosaur ancestors, feathers have evolved into impressive biological structures that come in a surprising diversity of colors and forms. Here, we cover the breadth of feather biology by looking at feathers from a variety of scientific viewpoints including their anatomy, function, development, and evolution.

Amazon Parrot tail feather illustration by Andrew Leach
From the fluffy down on a swan chick to the brilliant spiral on a King Bird-of-Paradise tail, feathers are remarkable not just in the way they look to the naked eye, but also for their intricate microstructure. Understanding feather anatomy at the microscopic level provides insight into how feathers function. For example, the interlocking Velcro-like structure on many bird feathers creates the smooth, flexible, and resilient surface that supports flight and sheds water.

As feathers grow, they mature into highly branched structures. Careful study of this process inspired new hypotheseshypothesis:an explanation that is testable through study and experimentation about the evolution of feathers through stages of increasing complexity. Newly unearthed dinosaur fossils from China and Canada have supported these hypotheses by providing specimens from each stage in the proposed evolutionary history—a clear example of how investigating biological structures across contexts can create scientific breakthroughs.

Feather Science From Many Angles

Thorough understanding of biological structures like feathers requires examination from many angles. We now recognize that how feathers function is intricately connected to how they’re structured, and how they grow is closely linked to how they evolved.

Tinbergen, via Wikimedia Commons
Niko Tinbergen, a 1973 Nobel Prize winner for his work to understand animal behavior, developed what he called the four levels of analysis that biologists have been using ever since to structure their research. For us to fully understand anything in nature, he said, we need to think about these four questions:

  • How does it work? (mechanism)
  • How does it function? (adaptation)
  • How does it develop? (development)
  • How did it evolve? (evolution)

Here we have taken Tinbergen’s advice and explored each of these questions to give you a comprehensive understanding of feather biology.


Fiery-throated Hummingbird detail - photo by Joseph F. Pescatore
Photo: Fiery-throated Hummingbird by Joseph F. Pescatore

  • Mark Mushkat

    Cornell Lab of Ornithology has made an important and highly valuable contribution with this website. Teachers, students and wildlife across the globe will benefit from increased awareness, better science, and more effective conservation this website will lead to. Thanks to all for their tireless efforts!

    • Mya

      Thanks so much Mark. It is nice to know that our efforts are appreciated!

  • Gaurav Jain

    Thank you Cornell Lab of Ornithology. As an amateur birder, this is very useful.

  • Royann

    As a professional artist doing mostly birds, as a bird carver, and as a teacher this will be awesome thank you!

  • Ellen Murphy

    Thanks so much for this! I have a program about Birds with a Homeschool group later this month and this is perfect!

  • john v. wylie

    Interested in Evolution.
    Baby chicks respond to “purrrrttt” sound made by
    hen (mother) and run for cover. Chicks raised in
    Incubator, no contact with adults displayed similar
    behavior when I tried to copy the sound. How did
    that evolve? Lots of lines of instruction, of no use
    part-way executed for survival, so how did evolve
    by little chance modifications of dna?

    • Matthew Tynan

      Hi! John V. Wylie.
      Baby chicks don’t do that by chance. God made them to do that.

      • Mya

        Thank you for your posts, perspectives, and interest. We’ve created this comment section as a forum to talk about birds and biology. Moderators will attempt to keep this discussion focused by removing comments that stray off topic. Please continue to use this space to marvel at birds, ask questions about biology, and share relevant resources!

  • Jimmye Porter

    So excited with all this information available. I have shared with my grandsons 5th grade Science Teacher (who was just awarded a National Teacher of the Year Award for Science).
    My grandchildren will be coming over after school today, can’t wait to let them explore. They both love the Merlin Bird ID, which they have on their iPad minis.
    Thank You All So Much

  • Pepper Trail

    This is a great overview of feathers – one of the true marvels of nature. As an additional resource, I suggest The Feather Atlas of North American Birds, at This site, a project of the U.S. Fish and Wildlife Service, provides high-quality digital scans of the flight feathers of over 300 species of North American birds, including almost all hawks, owls, waterfowl, and gamebirds. It’s a great tool for feather identification, and a popular resource for educators and artists.

    • dave

      i disagree

    • Ron Gretz

      I would have to tend to disagree. While the Feather Atlas provides some good scans the feather identification tool is incomplete. I came across a feather years ago in the front yard of a friends house in Oklahoma City after this huge bird took to flight when I pulled in his drive way. It did not fit any of the descriptions found in the feather atlas and the only outstanding feature of this feather is that when it fell from the sky, it measured 22 inches (55cm) long from tip to end of quill. It had none of the coloration of any of the eagles, vultures or condors and was way too long for any hawks or owls. I remember it being a dull pale white with alot of mottled light oranges and bronzes the entire length of the feather. I have wondered for years what kind of bird it was I saw.

  • Natu

    Thank you! this is just wonderful in every way

  • yogesh

    i want to know the chemical that causes the birds feathers so soft,silky and strong ? please reply. i need it for the project report.

  • Lexie

    Man, i am only a kid, but i am facinated by birds. i have always wondered how feathers grew……

  • Jeff

    I like birds

  • Slider

    Birds are fascinating I would love to know how they stay so soft and silky but yet super strong

  • Slider


  • bob frank

    this is no help at all!

    • Mya Thompson

      Just wondering what kind of information you were looking for. Perhaps I can help you find it.