Pages

Sunday, March 3, 2013

How Do Birds Stay Warm?

This is a question that has been asked and pondered by many young and old birders. My friend Ron Patterson has graciously given me permission to share the answer from one of his recent newsletters. The link will be given at the end. 



I enjoy watching the birds feed and that is difficult to do at a snow covered feeder.
Do you notice how chickadees will snatch and run?
Watch chickadees and you will observe them selecting just the right seed (by weight) and take off to a protected area to pick it open.
Chickadees need to find a seed worthy of their effort so the actually weigh them.
They need a lot of energy and no
time to waste on sunflower seed with a small meat inside.
Nuthatches will grab and place the seed or peanut meat in a crevice and peck away.
Jays seem to swallow whole.
These birds will also stash or Cache seeds in hiding spots for emergency feedings.
Studies have shown that these birds can recall hiding spots for at least 30 days.

Brown-headed Nuthatch

I like to watch other birds like cardinals and finches work a seed from the hull.
How they maneuver the seed around, get the goods drop the empty hull and grab another seed.
Another thing you can observe this time of year is the pecking order of your bird population.
Yes, in many species of birds there is a hierarchy.
There is often an Alpha male.
For Northern cardinals, it is easy to pick him out.
The most colorful or brightest red bird is the boss and gets first feeding rights, followed by his lady.
He also gets the choicest breeding grounds.
For other species, it is more subtle, but easy to pick him out be watching for a few minutes.
Sometimes it is the elder statesman, or it could be the most aggressive male.


The thing is, you can watch and learn who's the boss.
After that, there is the Beta and down the line, much like the pecking order in a wolf pack.
If you have some time, sit down and watch your feathered friends.
Sometimes it is an act of aggression, or even a subtle body posturing.

You may even observe other birds sitting back and waiting their turns.
This time of year, birds will show up in loose flocks or small groups.
In that group is a dominate male.


I have several feeders and sometimes, I think just to assert his bossiness, the Alpha will chase others away.
When this happens, several birds of a feather will move to the front yard feeders and visa versa.
Other times, everyone eats in harmony.
It is a wonderful scene to see your feeders and yard full of birds.
Helping birds in the winter is becoming more important with the decline of habitat.
Helping wildlife not only helps them, but helps you as well.
You can't help but feel good about yourself when you help out some one else, or in this case, helping wildlife.
Now here are some important ways that "Nature" helps birds to stay warm during the cold winter.



Winter poses several challenges for our birds as well, especially when the temperatures dip and dip some more.
We don't often think about or wonder how our birds survive the colds nights, we just know they do or at least we hope they do.
Even those moments in the deep South, Desert regions or the Pacific coast where a cold snap or several inches or feet of snow fall, can effect a bird
population.
Winter brings extreme cold temperature, strong winds, driving snow and rain.
Nights seem to last forever.
16 hours of darkness and in some locations more fall on the land.
That doesn't leave a whole lot of time to forage and feed.
Yet, many birds must at least triple their normal intake to survive and do it in half the time.


Each winter we lose many of our feathered friends to the rigors of winter.
It's how "Nature" works.
Survival of the fittest.
Passing on the strongest genes.
Birds have many adaptations to survive the extremes of winter.
Some birds migrate.
Some adjust their diet habits.
Birds such as chickadees and American goldfinches add feathers in preparation for winter.

Yes, the typical chickadee or goldfinch is covered with about 1,000 feathers during the summer.
By the time winter arrives, they have doubled that count to more than 2,000 feathers.
For a small bird, that can be some serious added bulk and weight.

American Goldfinches

By doing this, they create dead air pockets, much like insulation or a double pain window.
This reduces the heat loss by up to 30%.
Extra feathers and fluffing isn't enough to make it through a cold winter day yet alone the cold, long dark nights.
If you've been with me any length of time, you have read about blood circulation and bird legs.
Pay attention to this now.
Warm arterial blood from the birds interior, which is on its way to the bird's legs and feet, passes through a network of small passages that runs alongside the cold returning blood veins from the feet.
The network of vessels acts like a radiator and exchanges the heat from the out-going warm arterial blood to the cold venous blood.
By warming up the old blood, no heat is lost and the feet receive a constant supply of life sustaining blood.
This is also why water fowl can swim in near freezing water and not get cold.
In the summer, this works as a bit of an air conditioner.


A Side Note:
Because the blood doesn't warm up a bird's feet and because of the scales (no skin, no sweat) birds don't freeze to metal poles or birdbaths.
I digress.
Fat is another important winter weather survival adaption.
Fat acts as an insulator in addition to an energy reserve.
During the day, birds eat to build up fat reserves.
On average, a bird can put on up to 15% to 20% of body weight in fat before it becomes to heavy to fly.
Now remember, days are shorter and cold.
Birds have to eat enough to survive the day as well as replenish the fat reserves.
The smaller he bird, the higher the metabolism (more energy burned).
Birds don't have brown fat, the kind we have.
Instead they have white fat.
White fat is a high-energy fuel used to power the bird's warming process.



Red-tailed Hawk

Shivering:
Thermogenesis is a fancy name for shivering.
You can't really see it, but all birds shiver in the cold of winter.
From the largest of birds like eagles and water fowl to the smallest of birds like hummingbirds.
They all shiver to maintain their core body temperature at about 106 to 109 degrees, depending on the species.
That is an amazing high temperature compared to the surrounding air temperatures.
This past week in some locations, that is more than a 150 degree difference.

WOW!


Shivering produces heat five times their normal basel rate and can maintain a normal body temperature for six to eight hours at temperatures dropping to minus 70 degrees Fahrenheit.
Without shivering the bird's body temperature would quickly drop and the bird would become hypothermic.
I might add this, penguins only shiver if a patch of skin is showing, or there is some feather damage. Penguins are a different sort.
At night, birds such as the little chickadee take shivering, or lack of one step further.
To conserve heat and energy, chickadees can lower their body temperature by interrupting their shivering.
These periods of inactivity allow the bird's body temperature to slowly cool, until it drops about 10 or 12 degrees.
At this point, the bird enters a state of unconsciousness called torpor.
Respiration and heart rate will also drop during this period.



Carolina Chickadee
Energizing:
As morning nears, the periods of inactivity decrease until the bird is constantly shivering once again.
The body temperature is back in the normal range and the bird regains consciousness.
The results of this torpid state is an energy savings of up to 20% during a typical winter night. (much like you and me turning the thermostat down before we go to bed).
Conserving energy is very important when you consider how little fat a bird can store.
Based on a daily increase of body fat of 15% a typical chickadee has about 16 to 24 hours of fat or energy reserves to carry it through a winter night.
That my friend is why it is imperative that a bird gets out early in the morning and stays out late to find food regardless of the weather.
If it doesn't replenish its fat reserves every day, the bird will not have enough energy to make it through the next night and will die.
There was a time when the natural world provided food for most wildlife.
With the constant shrinking of habitat, winter protection and food supplies continue to shrink.

You can increase the odds for birds and some mammals by simply filling your feeders with their favorite food and offering suet.
Fresh water is important as well.
When birds are required to eat icy cold snow, it takes valuable energy to warm that snow as it passes through.
Next time you trudge out into the cold or even the warmth to fill your feeders, think of this...............
God has provided birds with some wonderful tools to survive, whether it is migration, blood circulation, change of diet, added feathers, or shivering.
Birds are truly a wonder for us to enjoy.
In one way, it is unfortunate that many birds now need our help to survive.
Yet look at the education and joy we get out of caring and feeding our birds.
Not to mention that feel good all over feeling we get.

Thanks Ron for sharing your knowledge! 

If you enjoyed this post then you will love Ron's Gardening for Wildlife. Go there and sign-up. You will not regret it! 

Wishing Peace, Health, Love, and Wealth to ALL!










ShareThis

LinkWithin

Related Posts with Thumbnails