As winter approaches, the days get shorter and temperatures drop. Whether it’s pulling on a down-filled coat or snuggling under a down comforter, we often have feathers to thank for the warmth we feel. Have you thanked a bird lately?

That’s right! We have birds to thank for that stuff we call “down” that is packed inside coats, sleeping bags, comforters and pillows. Down is the name of the fine feathers that many birds have under their outer feathers.

It seems odd, though, doesn’t it? If bird feathers are so warm, why do so many of them head south for the winter? As it turns out, most birds migrate to find food, not because they’re cold.

Down feathers are great thermal insulators. The loose structure of down feathers traps air.

As a result, energy cannot be transmitted easily through down feathers. This means birds are insulated from cold air outside, plus their body heat doesn’t escape easily either.

Human beings discovered that down feathers are good for insulation long ago. For example, documents from the 1600s show that Russian merchants sold “bird down” to the Dutch hundreds of years ago.

Today, down is used in all sorts of products, including coats, bedding and sleeping bags, to help better insulate the user from cold weather. Down can be collected from many different types of birds, but most of today’s supply comes from domestic geese.

About 70 percent of the world’s supply of down comes from China. Most of the down comes from birds killed for their meat. A significant supply of down also comes from Europe and Canada.

In the United States and Europe, it’s illegal to pluck down from a live bird. However, live-plucking is known to occur in Poland, Hungary and China. Animal welfare groups still fight to stop the practice of live-plucking wherever it is discovered.

If you have a down coat or comforter, is it all down? In the United States, laws require that products labeled “100 percent down” contain only down feathers.

If your product is labeled “down,” it can contain a mixture of both down feathers and synthetic fibers. Not all down feathers are created equal, though.

Down insulation is rated on a measure called “fill power.” The higher the fill power, the more the down insulates.

The highest fill-power rating — 1200 — goes to eiderdown, which comes from the Common Eider duck. Eiderdown tends to be expensive.

Don’t worry, though. Down with half the fill power rating of eiderdown still provides good insulation from the cold.

In addition to being warm, down is also lightweight and durable. If cared for properly, down lasts longer than most synthetic fibers. When it comes to down, though, it does have one downfall (pun totally intended).

If down gets wet, its thermal insulation properties basically disappear. When exposed to moisture, down will clump and mildew.

If not dried out properly, mildewed down will begin to have a foul — or is that fowl? — odor. So make sure you keep your down products nice and dry!


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    • We’re so happy to hear that you visit Wonderopolis every day, Hannah! We also think it’s WONDERful that you like learning new things with your classmates! Did you know that many of the ideas for our Wonders of the Day come from amazing Wonder Friends just like YOU? You can let us know what you WONDER about by clicking on the “nominate” link that’s found at the top of every page in Wonderoplis and answering a few easy questions! It’s FUN to nominate ideas for future Wonders…we hope you’ll give it a try! :-)

    • We agree…they ARE super cute, Natalia! Thank you for visiting this Wonder of the Day® and for leaving us an awesome comment! :-)

    • Hello, Noah! Thanks so much for leaving us an AWESOME comment! We hope you learned some new things by visiting this Wonder of the Day®! :-)

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  1. That had lots of facts in it. The picture of the ducks was so cute. The highest fill-power rating — 1200 — goes to eiderdown, which comes from the Common Eider duck. This fact was my favorite!!!!!!!! Thanks for a great wonder!!!!!!!!!



    • We’re glad you left us a comment to share your favorite fact from this Wonder of the Day®, Megan! Thanks for hanging out in Wonderopolis today! :-)

  2. Awwwwww! Those ducks are sooooo cute!! :) I used to have a pet duck! I found out that ducks REALLY like dog food! My duck’s name was Mallerie. I love the name Mallerie, especially for a duck! LOLzzz

    • That’s SUPER cool that you had a pet duck, Jessie! Thank you for sharing about Mallerie…we bet she was cute! QUACK, QUACK! :-)

    • That’s a really good question, Jessie! We think those ducklings in the video are some of the cutest down feather bearers we’ve seen in a long time! :-)

    • Thanks for WONDERing with us, Talia! Here’s a link to an image of down feathers. They are fine and soft. Most of the time, down comes from ducks that are already being raised as food. Thanks for hanging out with us in Wonderopolis! We hope you have a WONDER-filled day! :)

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Have you ever wondered…

  • How can down warm you up?
  • Which animal supplies most of the down feathers used today?
  • Which type of down is the best insulator?

Wonder Gallery

baby ducks_shutterstock_57152605Vimeo Video

Try It Out

Ready to warm up? If it’s getting colder where you live, you may want to get out your long-sleeve shirts, pants, down coat and a down comforter for your bed.

Keeping warm in the winter can be expensive, though. It can take a lot of energy to heat a house and keep it warm all winter.

But guess what? There are things that you and your family can do to make your home more energy-efficient.

Try some of the ideas below with your family. Not only will you make your home more comfortable in the cold months, you’ll also save money and lessen your impact on the environment by conserving energy.

  • Turn it off! Look around your house. How many things are plugged in? How many lights do you have? All those things use electricity. When you leave a room or finish using an electrical appliance, turn it off!
  • Turn it down! What temperature is your thermostat set on during the winter? Experts recommend setting it at no higher than 68° F. Keeping your thermostat set at a lower temperature will save energy and money. You can use heavier clothing and extra blankets to stay warmer if you get chilly.
  • Think green! As you go about your day-to-day routine, think about ways you can reduce energy usage. If you have curtains or blinds on your windows, keep them closed. This will help keep heat inside where it belongs. Take showers instead of baths, and make them quick. Heating hot water uses a lot of energy. Every place you can cut back makes a difference!


Still Wondering

Check out Smithsonian’s History Explorer’s The Feather Trade and the American Conservation Movement virtual exhibit. Learn how the 19th-century vogue for feathers as fashion adornments threatened many bird species with extinction.


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