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Bird Muscles, How and Why
October 09, 2017
The Gardenia looks good again this year.
We had some rain this weekend.
Not enough to be a drought buster, more than an inch, maybe two or so (depending where you live), is was a God send for sure.
Akita has recovered nicely from her teeth removal (five incisors).
The other fur kids remain in full kid mode.
Our seven year old grand daughter spent most of the weekend with us.
She was a big help for grandma, as they spent Saturday afternoon shopping (must be a genetic thing).
We never did make it to ARTPRIZE this year.
Too hot, and then too busy.
Plus like so many other venues, It is becoming too political for us.
At least Yolanda and her 'Hope Network' group made it a couple of times.
I'm finding time to dry herbs (dehydrator), and slowly begin to cut a few things back, in preparation for winter.
This may very well be the last vase of cut flowers.
On evening (now nighttime walks walks), I can hear the Killdeer.
Often times I can hear migrating birds fly over head as they call out from time to time.
Yes, every season gives me some joy.
A second wave of fledged
American Goldfinches have graced us with their presence.
We so enjoy the sounds of the youngsters, as they beg for food.
Still expected is one or two nests of fledged Northern Cardinals.
Every fall we get some late fledglings.
Checking things out, needing to see what needs to be cut first, etc. I spot this Praying Mantis, blending in to the rose bush.
This is a Chinese mantis, originally brought over to help with invasive bugs.
Chinese Mantids (females) are a healthy four inches (10 cm) in length, much larger than native species.
Karen wonders how I spot things so quickly.
It become easier, as you are in tune with nature.
Nature never ceases to amaze.
Most, if not all of you have eaten chicken at one time or another.
Fried, roasted, baked and so on.
Some of you prefer the white or breast meat while others prefer the dark meat (legs, thighs, and wings).
I like the dark meat, more flavor and better for me too.
So what is the difference?
Dark meat is composed of red muscle fibers (cells).
The red color comes from a high concentration of myoglobin in the fibers.
Myoglobin, like the hemoglobin in our red blood cells, binds oxygen that can be released as needed to the muscle fibers to allow them to contract.
The myoglobin increases the entry of oxygen to the muscle fibers.
Contraction of muscles allows for such useful activities as walking, flying and capturing food.
Red muscle also has an abundance of capillaries to help provide oxygen to the fibers.
These muscle fibers are quite narrow and so have a very high surface area relative to their volume.
As a result, oxygen does not have to move very far as it diffuses into the muscle cells.
The flight muscles of small songbirds (and small bats) have the highest aerobic capacity of any vertebrate species.
Red muscle fibers are often referred to as slow twitch fibers.
The fibers contract but at a relatively slow rate.
The fibers require lots of oxygen to do their work but this oxygen is provided by the blood and stored in the myoglobin until needed by the muscles.
(Do you see how the special lungs and sacs from last week's letter come into play?)
Because of this, red muscles can do slow but steady work; they do not tend to fatigue.
Red muscles are excellent for sustained flight.
You can now understand that migrating birds primarily stop to feed, sleep, during foul weather or when they lose the protection of darkness.
They don't stop because they are winded (last weeks letter), or fatigued like other animals experience.
The breast of a chicken and in game birds like pheasants on the other hand, is made up of white muscle fibers.
These muscles are not well supplied with capillaries and do not contain much myoglobin to help store oxygen.
White fibers are often referred to as fast twitch muscles and are capable of very rapid contraction.
However, these contractions occur in the absence of oxygen.
After a short period of time, a waste product called lactic acid accumulates in the cells, causing the fast twitch muscle fibers to cease contracting.
White fibers are therefore capable of a few very powerful, very strong contractions but tire quickly.
In game birds, the muscles of the thigh and drumsticks are composed of red muscle fibers.
(The same goes for domestic chickens and turkeys.)
These muscles are used for walking and scratching the ground.
The muscles do not have to act particularly quickly.
Because they are slow twitch muscles, they do not tend to fatigue.
A wild turkey or quail can walk around all day without experiencing muscle fatigue, ........ can you?
Besides, have you ever seen how fast a wild turkey can run?
The flight muscles of these birds (the breast muscles) are white, fast twitch fibers.
When alarmed, these can use those fast twitch fibers to take off explosively.
You may have kicked one up at some time or another as it startled you as well.
However, the flight must be a short one because those white fibers quickly fatigue as lactic acid builds up in the muscles.
In most birds however, breast muscles are not made up of only white fibers or only red fibers.
In most birds, the red breast muscles have a few white fibers scattered throughout.
Exceptions to the rule occur in the breast muscles of sparrows and hummingbirds that only have red fibers.
The relative quantity of slow versus fast twitch muscles is related to the particular life style of a bird.
For long distance migrants like tanagers, swallows or warblers, their flight muscles must be able to sustain long periods of use.
White fibers would be poorly suited to the task so it comes as no surprise that the breast or flight muscles of these birds are mostly red muscle.
On the other hand, the great power but short duration of white fiber contractions makes white breast muscles suitable for birds that need to take evasive action in flight to avoid predators or to fly through thickly forested habitats.
This holds true for many birds of prey (Cooper's Hawk for example), that rely on short bursts and quick take offs.
It also helps to understand the important requirements and abilities these birds have to soar for hours on end.
The size of the breast muscles in a bird is related to its flying ability.
In birds that are powerful fliers, over 20% of the bird’s weight is breast muscle.
In birds that do not fly, less than 10% of the body weight comes from the breast muscles.
The skeletal muscles play another important role.
In the winter, when the temperature falls below a critical level, the skeletal muscles begin to shiver.
These rapid, involuntary contractions release heat to help the bird maintain its body temperature.
This too requires a constant supply of oxygen, which goes back to the wondrous lungs of birds.
There you have it.
Besides healthy feathers, the proper breath support, and muscle groups are required for migration.
It just so happens that Creation has supplied birds with everything they need.
Well, it's time to fly for now.
Before I go, here is your positive thought for the week.
"I am only one; but still I am one.
I cannot do everything, but still I can do something;
I will not refuse to do the something I can do".
Helen Keller (1880-1968) American Writer
I am only one, yet God's word lets me know I can do something special too.
"I can do all things through Christ who strengthens me".
"Treat the earth well:
It was not given to you by your parents,
It was loaned to you by your children.
We do not inherit the Earth from our
Ancestors, we borrow it from our Children."
Ancient Indian Proverb.
Your friend indeed,
Better yet, have them sign up so they can receive their own letters.
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