How do birds survive the cold weather, especially during really cold winters like the one we are having now in much of the United States?
One part of this answer has to be, sadly perhaps, that the sometimes don't. But I'll get to that later.
You need to know two things as context. First, there are a lot of different kinds of birds, and the adaptations I'll mention below are not found in all of them, and probably all of these adaptations are not found in very many species. Second, many birds are actually at great risk during cold periods because birds generally live on the edge when it comes to energetics. It takes energy (from food) to keep warm. Birds are endothermic, meaning that they produce their own heat (mostly) via blood flow in their bodies, but unlike mammals, birds change their body temperature a fair amount, so the amount of heat they need to produce to fly is a little bit flexible. The thing is, temperate and sub-Arctic birds have to survive not only the cold of winter, but even the chill of a non-winter night. Since they don't store a lot of energy in fat (that is hard to do for a flying animal) it is quite possible for a bird to run out of heat-producing energy overnight even when it isn't winter. That would amount to, essentially, starving to death. So, some of the adaptations for surviving the cold apply year round, depending on conditions and the species.
There are several things birds do (or avoid doing) to help them survive the winter.
First, they can leave. Migration is a great strategy to avoid winter. I highly recommend it. Migration is costly, though. One has to spend a lot of time flying instead of feeding, and a bird is probably more susceptible to predation while flying through the territories of various predators and spending time in areas it is not familiar with. Most migratory birds that die during migration probably do it on their first migration, and thereafter have the advantage of knowing the territory a bit better. So, migration is one way to handle winter. Note, however, that there are birds that live in the Arctic or sub-Arctic that migrate south to regions where it is still winter. (Some of these are referred to as snowbirds because they show up during the snowy season).
See Also: Feeding Wild Birds
Birds wear down coats. All their feathers help them to keep warm, but especially the downy under feathers (called, of course, "down") act like tiny little North Face down coats. Some birds probably grow extra down during the cold season.
When you are trying to stay warm, water is your enemy. Air makes a good insulator but water transmits heat, so wet feathers are bad. So, birds have oil producing glands that allow them to preen a coating of waterproof onto their feathers to avoid the down coats getting wet.
Birds have legs and parts of their faces that are exposed. But they can sit in a position that covers, or partly covers, their legs and feet with their down coat. They can also hunker down in a protected area, with less wind-chill causing wind, in the canopy of an evergreen or some other place. Gregarious over-wintering birds like Chickadees will roost together in little bird-lumps to give each other protection and warmth.
Birds shiver. That helps get added heat from circulation and muscle movement.
Bird feet are covered with scales and have very little cold-damagable tissue in them. They are mostly bone and sinew.
Some birds have a special adaptation in the circulatory system of their feet (and maybe elsewhere) whereby blood is circulated between colder outer areas and warmer inner areas more efficiently than might otherwise be the case, to avoid frostbite.
Check out: Books on birds and nature.
Birds can not only tuck their feet in under their down, but they may also switch which foot is holding them on a branch. Also, as you probably know, bird feet are generally grabbing at rest, so it takes very little energy to stay attached to a branch. The default is "hang on." Sort of like the safety feature of an Otis elevator, where the default position for the machinery is "don't drop" so when the power goes off the elevator gets stuck instead of plummeting to the bottom.
Birds may find a place in the sun and use a bit of solar energy. This, of course, depends on the wind. It also puts them out there for predators to find them, but it can work.
Birds may eat more, or selectively eat higher energy food during the winter. For small birds this may include storing up food during the warmer season. They are adapted to find, store, and remember where the food is so they can find it quickly. This makes winter foraging super efficient.
Some birds store some fat, but really, that is not a great strategy for birds that fly.
One of the most effective strategies for having enough energy from food to stay warm is to not do highly energetic things during the cold season. I already mentioned the increase in foraging efficiency for birds that store food. Another obvious strategy is to not do energetically costly things during this season such as defend territories, spend a lot of time singing (singing is very costly in terms of energy), don't build or maintain nests, don't produce eggs or have hungry chicks around. This may seem self evident but it is actually very important. Indeed, the reproductive success of a pair of birds in a given year may be significantly hampered by late cold weather or forage-covering snow storms in the spring.
Finally, birds use another strategy that also works against the cost of predation and other forms of death: Reproduce more. Most pairs of birds produce one or a few offspring that become adults a year for five or more years. If all of those adult or subadult birds survive and reproduce, we'd be covered in birds in a few decades. But lots of things kill birds, including predators, disease, starvation, and cold.
Here is a pretty good video that covers some of these things:
The photo of a Dark Eyed Junco is from HERE, where you will also find a bit more discussion on birds in winter.
I also write about birds here.
Also of interest: In Search of Sungudogo: A novel of adventure and mystery, which also explains the link between Bigfoot, Aliens and Sex.
Other posts of interest:
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Thanks for this post.
This is the first winter in a few years which reminds us of the harshness critters face subsisting near their bioenergetic edge.
If you've not read naturalist Bernd Heinrich''s book on now some of these animals survive and their adaptations, you might like it. It is titled "WinterWise: The Ingenuity of Animal Survival." One of the most intriguing is the Golden Crown Kinglet which weighs in the neighborhood of two pennies. It is a full-time daily forager before retiring for a chilly night, often just making it to first light when it begins again.
Heinrich also is the author of "Ravens in Winter." There is not much that his eye misses and he is very clever about setting up field experiments
An essay I read every winter once or twice is Aldo Leopold's "65290" which traces the life of one of a small group of chickadees to Leopold's last identification of this banded bird. It is a story of winter survival and I've thought about it often during this winter.
Leopold writes, "To band a bird it to hold a ticket in a great lottery. ...It is an exercise in objectivity to hold a ticket on the banded sparrow that falleth, or on the banded chickadee that may some day re-enter your trap, and thus prove that he is still alive."
Those are great suggestions, Ed!
Birds are very unique animals and the way other animals stay warm during the winter is unique as well. Some monkeys in Japan take baths in heated springs. Frogs in the US and Canada use high blood sugar, urea and a chemical that acts as antifreeze to stay worm. Penguins huddle together for warmth. And unlike birds who you mention reproduce more, some animals slow down to conserve energy. https://www.sciencenews.org/blog/wild-things/eight-ways-animals-survive…
Thanks for the great post! I feel compelled to comment because I was just discussing with my peers how the seagulls that fly around our school's campus survive the cold winters. We were curious as to why they don't leave and after reading your article, I feel confident that i can go back to my friends with an answer.
I had never considered how much of an impact a bird's feet had its temperature. I was interested to find that human's have a similar blood vessel mechanism in our extremities. http://www.livescience.com/34411-body-heat-loss-head.html
Very well done. All bases covered. Birds are amazing!
Dave, thanks. Hey, I have a question for you. I'm getting hundreds of hits on this post from facebook. Where did you see a link to it? I can't tell by using the usual methods.
Great piece! I came here via Facebook - a friend shared a link directly to this page, nothing obviously stating where friend got the link - but if I go to the advanced post options, I can hide all posts from "Knowledge is POWER" - I can't find that page or anything further. If I go to my friend's timeline to look at the same post (instead of connecting to this story via news feed), the "Knowledge is POWER" piece does not appear, not sure if it's relevant!
Josie, thanks for the info! Facebook is so strange...
Do wrens go south for the winter? I live in southern Iowa and one has been coming and eating the suet cake. That is the first time I have seen one in the winter.
There are all year round wrens in your area, but different species are very different. What species are the they?
"Also, as you probably know, bird feet are generally grabbing at rest, so it takes very little energy to stay attached to a branch. The default is “hang on.”"
This is not strictly true for all birds. Many birds do have an automatic grasping reflex for holding onto branches while at rest, but many do not. Many birds have to make a conscious effort to hold on to branches when they are perching. Birds that build nests generally do not have this automatic grasping reflex since they don't need it. The only birds that need it are birds that sleep while perched so they won't let go and fall during the night. Birds that hunker down in a nest or other structure don't have to worry about falling.
Joe, most birds that build nests use those nests only seasonally, but sleep nightly, so I'm skeptical that your correction is correct as stated. But there may well be birds that don't automatically grasp at rest. I'd like to get a better handle on it then I'll fix that statement, thanks for the heads up!
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I didn't see mention of some birds ability to lower their body metabolism, energy consumption and body temperature in cold weather. Some birds rest more and use less energy when in that state. This is a very important adaptive mechanism for some cold weather birds. See; https://web.stanford.edu/group/stanfordbirds/text/essays/Temperature_Re…
reduced energy use is mentioned. thanks for the link on temperature regultion! ill try to include it.
When tree branches are snow-laden, both older and younger birds prefer to be in the lower branches where it is easiest to find food.
To avoid heat loss in strong winds, most tits congregate on the lower branches of the trees' lee side, where the wind penetrates least.
In both of these weather situations, young birds have less time to forage since they need to keep an eye out for the older birds and other predators.
i would like to pin this on a board for use in our forest school in the winter term. We make bird feeders and I think this is a great way for them to understand how it helps. Please allow Pinterest?
Thanks for the info I think it's great!
Just a slight comment on the following statement:
Most migratory birds that die during migration probably do it on their first migration, and thereafter have the advantage of knowing the territory a bit better.
The way this reads, you are saying birds that die have the advantage... I believe you mean if they survive, they have the advantage.
Interesting how these birds surivive a harsh Montana winter, but they do it. I want to mention something of an argument to your article.
A large gang of at least 50 birds live in a thatch, leading down a hill along the sidewalk to work. Anyway, these birds sing and tweet like a choir when its sunny but negative 1. As I approach they all get quiet, but as I pass by maybe twenty feet past, they all start singing again. I figured it was to help they keep warm, but perhaps they are mating? Any ideas?
Do you know what kind of birds they are? They may be a snowbird, like juncos or something. They do make some noise using contact calls to stay informed about each other's movements.
Do you actually see them? Maybe there's a speaker in the brush and somebody is playing a joke on you!
As per taking pictures, I just love these big birds. They are engineering in flight! A marvel to look at, both in the air and on the ground.
Hi Greg, thank you so much for posting your fabulous article. In warm and cold weather I always have bird feeders and water areas for our garden birds. They appreciate it so much and I love watching them all. I always worry about how they are keeping warm and your article has explained it perfectly.
As that is the elephant in the closet and because I was unable to find anything definitive anywhere online, I wrote the always brilliant Rudy Winston. Below I share his e-mail with you. My brief comments follow.
i have child of eagle and i dont know about it. plz help me .. whats feed ?? i dont know plz help .
0092 300 8905855
"Most migratory birds that die during migration probably do it on their first migration, and thereafter have the advantage of knowing the territory a bit better. So, migration is one way to handle winter. "