Birds & Birding

How Do Birds Stay Warm on a Cold Winter’s Night?

January 19, 2016

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Swallows in a snowstorm. Photo © Keith Williams / Flickr through a Creative Commons license

Winter is a challenging time for backyard birds such as cardinals, woodpeckers, nuthatches, chickadees, titmice and wrens.

But roosting in tree cavities, bird boxes and an assortment of makeshift shelters can help these birds stay warmer at night and give them an energetic edge.

Finding a snug place to sleep on a cold winter’s night is particularly important to Carolina wrens. They belong to a primarily tropical genus of wrens and seem to have limited capacity to deal with really cold weather and snow.

Carolina and other wren species nest in natural places such as upturned roots, tree stumps, vine tangles and tree cavities, but they also nest in a whimsical array of human artifacts. Roost sites and nest sites are often one and the same.

Birds of North America cites some favored nesting spots of the wren:

  • Glove compartments of abandoned cars and inside garages.
  • Old shoes and shelves.
  • Mailboxes and tin cans.
  • And an equally whimsical array of settings are listed as the wren’s roosting places:
  • Bird nesting boxes and abandoned hornet’s nests.
  • An old coat pocket and a hanging fern.
  • Garages and barns.
  • Squirrel nests and old bird nests.
  • And at least one ceramic pig planter.
Carolina wren nesting in a pig planter. Photo © moccasinlanding / Flickr through a Creative Commons license
Carolina wren nesting in a pig planter. Photo © moccasinlanding / Flickr through a Creative Commons license

It seems that any place that can support a messy domed nest of twigs leaves, root fibers and moss is fair game for a wren.

I can add retractable awnings to the list. Every year, a pair of Carolina wrens builds its nest in an awning over my back deck – despite the mechanical activity of the awning and all the commotion below it. And in winter the pair uses the nest for roosting as well, particularly when the temperatures are below freezing.

I can be reasonably certain these are the same wrens in summer and winter because Carolina wrens don’t migrate, and pairs stay on the same territory throughout the year.

It’s been documented that the northern boundary of their range ebbs south and flows northward depending on how cold or mild the winters are over a series of years. When sustained below-zero temperatures and snow descend on the landscape, the wrens simply perish.


Near the northern edge of their range, there are clear benefits of backyard bird feeding to Carolina wrens. A study in Michigan found that bird feeding may even be supporting their northward expansion.

The research showed that in winter, wrens disappeared from areas with no bird feeders and remained common in areas that had bird feeders.   It isn’t necessarily temperature that is driving wrens southward when the snow falls. It is their inability to find food during snowy conditions.

During the day, birds must eat enough to build up the fat reserves needed to keep them alive through long and cold winter nights.

Roosting in protected places gives the wrens (and other birds) a better chance of weathering the elements and conserving the hard-won energy reserves they gained during the day.

Studies of birds roosting in nests have shown that such domiciles confer critical energy savings. The same goes for roosting in tree cavities and bird boxes.


It’s not just wrens that are availing themselves of shelter when it gets cold. Woodpeckers and nuthatches nearly always use cavities to roost regardless of the weather, but chickadees and titmice resort to using cavities most often when it is very cold.

A study of the benefits of roosting in tree cavities on a cold night found that not all cavities are equal in their comfort levels. The bottom line of the research: cavities in bigger trees that are alive (not dead) hold the heat of the day longer and stay warmer at night.

Left tree. Photo © M. Rehemtulla for the QUOI Media Group. Right tree. Photo © Alan Vernon
Left tree. Photo © M. Rehemtulla for QUOI Media Group. Right tree. Photo © Alan Vernon / Flickr

In the coldest times, some species will huddle together to stay warm. In his book Birds Asleep, Alexander Skutch shares this report on the tendency of winter wrens to huddle together on cold nights:

Nine slept in an old nest of a thrush,

Ten squeezed into a coconut shell and

Forty-six into a nesting box.

One observer noted over one hundred pygmy nuthatches entering the same dead pine trunk on a cold night. Bluebirds also roost communally in tree cavities and nesting boxes during frigid spells.

Bluebird. Photo © Mike Kilpatrick
Bluebird. Photo © Mike Kilpatrick

In milder weather, these same species tend to roost alone or in family groups. One individual winter wren was observed alternating between roosting alone and with other birds as the temperature oscillated from mild to frigid.

While our backyard birds might be just fine on their own, we can help birds by offering places for them to roost in winter.   The easiest way to do this is to have a variety of bird boxes available during winter. If you are really creative, you can try to expand the list of wacky places where wrens will nest and roost. Poke around your yard for potential roost sites and watch and listen for birds going to roost just after sunset on winter days.

Joe Smith

Joe Smith, PhD, explores the lives of the birds around us by sharing insights from scientific research. As an ecologist for a New Jersey-based conservation services company, he helps to restore coastal ecosystems and the migratory birds that depend on them. Joe lives in the birding hotspot of Cape May, NJ and has done field research with birds throughout the U.S. and Latin America. He writes about nature in his backyard at More from Joe

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  1. I live about 15 miles north of Bennett, CO. I have been finding dead finches in my yard. The temps here have been below 32 degrees at night and we have had some high 40’s during the day and there is still snow on the ground. It breaks my heart to see these poor birds like this! We live out on the plains.
    Is there some way I can give them more shelter? I have friends who “donated” their Christmas trees so they can get some more shelter. Would bales of hay help?
    I do feed them daily. Any suggestions would be welcomed!

  2. My father was an ornithologist and banded birds while I was a child. I would go with him to check the traps and mist net and watch him gently examine each bird, document and band them. Over the past 50 years, I have watched their sustaining habitat, here in Ohio, diminish into very small patches. The awareness factor of wildlife has been diminished along with the “born” responsibility as an American to care for our land. We use to see PSA’s on TV that would jar our conscience, but they too are a thing of the past. We were taught Respect for all living things…and if you could help the bees, critters, animals…you did so. It was a united – “given” in our society. God, help us….before they are all gone.

  3. For an accessible book with fascinating insights into how animals, including birds, survive winter, check out Bernd Heinrich’s book “Winter World: the ingenuity of animal survival.”

  4. I have a large patch of Bamboo in my backyard and literally hundreds of small birds roost there every night. The thickness of the bamboo provides warm and safe shelter. I love hearing their 10 min long chatter (seems like they all talk at once) at dusk and dawn. Happy to have them as co-residents in my yard.

  5. Add Christmas wreath to your list for Carolina Wren. I usually have to leave mine up as she spends the winter in it and then builds a nest in the spring.

  6. Out buildings that are unused could have small openings let into them as possible shelters for wild birds. Clean ice free water needs to be provided, and well stocked feeders with a variety of different fresh foods need to be supplied, above ground and away from potential predators. Cat owners should keep their house cats indoors; house cats are aggressive predators of wild birds, they can themselves be attacked by larger wild predators. There are any number of winter shelters that can be home made and placed in predator safe locations to aid wild birds over winter.

  7. I always worry about wild animals and esp the birds around here during cold spells. the fall was so mild, I observed many wrens still in the yard or at least heard them. now all of a sudden it is cold and ground is covered with snow. were they ” tricked ” into staying around? how do the wrens survive here. I have never seen one eating from the seed we put out. do they only eat insects? what about berries? is there anything we can do to help them survive? lucky we have 2 abandoned sheds with several openings for birds to find shelter maybe. we live in southern n.j. , one mile from the bottom of the turnpike. thank you, I enjoy your writings, f

  8. “there are clear benefits of backyard bird feeding to Carolina wrens. ” What are you feeding them? They’ll take meal worms, but as far as I know, that’s about it. They eat bugs, not seed, right?

  9. After the holidays I take my tree outside, stake it so the wind doesnt blow it over & decorate it with bird treats, suet, berries,etc . The birds love it!
    As we saw snow fall for over 24 hrs in the past 2 days, i noticed that many birds had burrowed through the snow on the tree to make little “igloos” where they roosted, apparently keeping warm & protected from the extreme temps. A variety of birds including juncos, finches, sparrows & titmouses continued to stay in the tree even after the little white lights came on. They usually roost in a tall privet hedge along the house, but perhaps they liked having an extra bit of warmth from the lights?

  10. I had a Carolina wren who built a nest in the engine of my tractor and stayed there all winter. My parents live in Indiana, and they have a terra cotta wallhanging in the shape of a face, and the wrens have built nests in the nostrils of it! They are very adaptable ;-).

  11. Hi, I have a pair of Carolina wrens that have 5 eggs in a small nest just outside our side door under a porch, it’s April 1st, in the next week Charlotte temperatures are suppose to be possibly freezing at night for a few nights,is there anything we can do to help keep the eggs & wrens warm, or should we let them be & hope for the best? Thanks Thomas

  12. Thank you for this article. I feed the birds and squirrels and many animals that come at night. It is really cold here in southeast Virginia tonight and I was worried about two Carolina wrens that sleep inside the folds of my largest patio umbrella. I usually put it away in winter but not this year! I have it pushed against my screened back porch behind a brick wall of the house. It keeps them sheltered from the wind and rain. They tuck themselves in every night at the same time. As it started getting darker earlier each night they started to come a little earlier, just like “clockwork.” I wondered if I should put some hay in there somehow but I’m concerned I will scare them off, even though they are bold, little birds… I just adore them!

  13. Thank you for this article. I’ve had bird boxes in my garden for years, but have never seen a bird avail
    itself of the shelter. Am I doing something wrong? Placement maybe? Zetta

  14. my young bird doesn’t fly or sing when the house is cold. i would like to know should i keep a warm house. also i smoke everything sometimes i think my bird gets a buzz. can anybody tell me what is up. i let my bird fly freely around my apt. he omnly uses the bathroom on paper. i think he has respect. he also comes and sits by me and sleeps where i sleep. i think my bird is smart and cool. tell how do i know if he is happy

  15. I want to join the Nature Conservancy to help support our environment and sanctuaries that help support wildlife and ensuring their future survival, creatures God gave us to protect and be stewards of, and the Earth He gave us to take care of, not just help bring it to ruin. Pleas send me a email how to contact Nature Conservancy by phone!! Thank you for the work you do, mm

  16. We enjoy feeding the birds, we watch them because the feeders are outside the kitchen Windows. We even have the approximate time they will start coming to eat, both in the morning and evening, (late afternoon.) But now reading this article we will start looking for places where the birds can roost for a good nights sleep!

  17. I have always wondered if bird feeders do more harm than good. Birds naturally adapt to temp changes by migrating, stopping ovulation, etc. We likely mess up their patterns honed by millennia of evolution, why? To feed the bird feeder industry, to see pretty birds near our house, and to feel good about ourselves. But what about the bird’s best interest? Inquiring minds want to know.

  18. I always wondered how birds like Chickadees could even be alive after a subzero night. So tiny and delicate looking in that ice and snow and wind. Guess they must have a secret place. Enjoyed this article.

  19. Lovely article. My husband and I have always wondered where the birds go to keep warm at night. Now we know!

  20. I thank God for gifted individuals like you. Living in San Antonio, Texas can have its rewards, however, for many years I have worried about our little feathered friends, especially during the winter months. During these frigid times (and other seasons as well) I tend to leave birdseed and other edibles for the birds that frequent my area. A dogwood tree in my backyard provides berries for migrating birds. Several families of birds have built nests under my roof’s eaves, and during the spring when they are mating, I provide clothes dryer lint and place it in areas where they can locate it to feather their nests. I was intrigued by your article and observations of birds during the freezing climates. Thank you so much for providing the information we so desperately need and giving me a piece of mind for our friends that bring so much joy, beauty and song to our environment. I will definitely keep in touch. P.S. You look awfully young for a professor! Great work!

  21. I live in Washington DC., and not sure what type of birds are in this area. For years I have been hearing bird chatter by my kitchen windows since the exhaust fan was broken. I hear more chatter in spring, summer and fall than winter months. I believe I became accustom to the morning chatter, since I denied to fix the kitchen exhaust fan. No alarm clock needed, the birds harmony wakes me with a sense of jovial.

  22. I love birds. This is a very interesting article, how we can have our part in keeping them warm. Thanks for sharing.

  23. I have 3 hanging dead ferns outside my kitchen window. Will the birds use them for shelter? I feed the birds year round. I only have 1 birdhouse. I never see a bird go in there. I live Northern New Jersey.

  24. I was particularly interested in your notes about Carolina wrens. I have had them overwintering near my home in southern Wisconsin, and I think their habit of storing mealworms that I provide as well as finding cavities for roosting has helped them survive.

  25. It is interesting to observe how these little birds make use of the instinct granted by the creator.

  26. Loved reading your article on Bird nesting in cold weather. As a senior and a resident of Woodlands Edge I am a Bird watcher from my upper deck. Thank you for the very interesting and informative article.

  27. I lived in NC for many years and we had several pairs of Carolina Wrens on our land. One pair nested in an u used fan duct on the 2nd floor of our house, and year after year, I enjoyed watching them build their nest, raise their babies, and watching the babies fledge. I live in upstate NY now, and have missed their antics and songs. I’m glad they’re here now. I haven’t seen any yet, but I will definitely build ha itat for them and hope they come! Thank you!

  28. Thank you for this. Just had a chickadee go into a bird box and not come out. Your article timing is uncanny.

  29. Great! And provide water in a heated bird bath if possible so the birds don’t have to work hard to find liquid water in frigid times.

  30. Thank you. I’ve enjoyed your post here. Specifically about the Carolina Wren.
    I’ve been enjoying the birds the past couple of years drawn to my insignificant feeders with an abundance of seed. Much strewn across my patio pavers or mulch bed.
    I’ve been almost intrigued by the Carolina Wren I have as they are less and less bothered by my presence . Perhaps our current artic blast here in North West NJ has them appreciating, and maybe realizing I’m the human hand that’s offering a generous supply of seed, nuts and suet. Along with several dishes of fresh water throughout the day?

    I find the Wren to be more of a loner,but hasn’t a problem when other species of birds join in for some grub.

    Happy Birding.

  31. I love watching and feeding the birds! We sometimes see -40 degrees and -65 with windchill! Where do our birds go for shelter? What can I do to help? We have numerous kinds in northern Minnesota! I do put out lots of suet for our woodpeckers also! We have two of the pileated that are around and enjoy the numerous crabapples from our flowering crabapple trees. We get quite a few grouse sitting in the trees also, but haven’t seen them for awhile. Where can our many finches, nuthatches, chicadee’s and grosbeak’s get shelter? Thank you! Mostly feed black oil sunflower seeds and store bought suet.

  32. Hi there, I loved this article. I have nest boxes in my yard which many of my birds use during nesting season. But I have a pair of Carolina wrens that nested one year in my garage in an Easter basket I left hanging. In spite of the racket of the garage door going up and down they never seemed to be bothered and we treated them royally while they raised their little family. I often see wrens in my garage but this winter I’ve noticed they are there late in the day and in early morning. Our garage door doesn’t close completely at the moment with a small opening at the bottom. I realized I never removed the old nest from the Easter basket and now I’m questioning whether or not to take it out in case the birds want to rebuild there this year? My concern is that I hate to remove the nest if there is a chance they may be roosting in there on cold nights. Do you have any suggestions? Thank you so much!

  33. I’m sorry, I had not read any comments but I live in Tallahassee, Florida.

  34. I observed a flock of robins
    near our crabapple tree —
    in Hingham MA ; early January 4th 2021 with at least
    30 or more in view. Temperature was
    32 degrees.

  35. Could you give me some ideas for bird boxes etc for winter protection. Make it cheap to do please.

  36. I routinely spread bark butter in the depression of a tree for the woodpeckers, bluejays, and wrens. We ran out of bark butter during the recent freeze in Texas and substituted natural peanut butter. They ate it!