The Body of an Eagle
Before we get to understand the flying mechanism of eagles, it is important to know how the body of an eagle is built. An eagle’s body structure is very suitable for flying and hunting. For doing physically demanding tasks like catching prey or flying, the body needs to be lightweight and strong at the same time. The weight of the body should be light enough for the wings to take it off the grounds, as well as strong enough to rush down on prey and carry it.
Eagles have hollow bones, which are light and strong at the same time. In some parts of an eagle’s skeleton, braces are placed inside bones to make them even stronger. Majority parts of the bones are shallow and have nothing but air inside. Though an eagle looks quite big, the entire skeleton weighs only a little bit more than 250 grams. Isn’t that fascinating!
The other important part of an eagle’s body is its wings. Eagles have very strong and powerful wings that enable the bird to fly high, and also carry prey at times. Eagle’s wings are very strong and lightweight like its bones, but the mechanism is entirely different. These wings are massive, and they are what makes the bird look so big. On average, an eagle’s wings are almost 8 feet long, but weighs barely 2 pounds. It is made possible due to the feathers being very light and overlapping. Due to the overlap, there are lots of air space between the feathers.
If compared pound by pound, an eagle has even stronger wings than an airplane. These long and wide wings help this great bird with very less effort. Due to broader wings, the bird can hold itself up in the air at low speeds. Birds with narrower wings are not able to do the same when speed is low. The wings also provide extra lift while carrying prey.
The Eagle’s body doesn’t have any extra ounce of weight anywhere. Despite having more than 7 thousand feathers, the total weight of all the feathers is barely 21 ounces. If one takes ten feathers in hand, it wouldn’t feel heavier than a penny. But that doesn’t mean the feathers are weak, rather these feathers are another example of the amazing body structure of this great bird.
Eagles have three different types of feathers, each playing a distinct role. The green feathers make the wings thick and strong in front, so that air flows faster over the wings’ top. On the other hand, grey feathers are the primary feathers that spread on the outside part of the wings to reduce drag. And lastly, blue feathers are the secondary feathers which the eagle can move down for increasing drag, or move up to reduction.
Despite being really light, eagle feathers are very strong. They are held together by over 350 thousand hooks. The hook parts are known as hook barbules, and the part where they are hooked are known as bow barbules. The feathers are made of keratin, the same thing that constructs human fingernails.
Like all the other birds, feathers are extremely important in an eagle’s life as well. Feathers do not only help the eagle to fly, but also provides an outer layer that covers the bodies. Moreover, the feathers are responsible for keeping the bodies of the eagles warm in high altitude where temperature is comparatively low. There is another important use of the eagle feathers. Attractive feather colors are important for the birds to attract the opposite gender and mate. Which means, feathers are an important tool of regeneration.
If the eagle feathers are looked through a microscope, it can be seen that thousands of spines exist in each feather, which are basically barbules. When the barbules are hooked together, the feathers look very smooth. The barbules might start to come apart if the feather gets lots of hard ware. When this happens, feathers look messy and rugged. This mostly happens in aged birds.
How Does an Eagle Fly
The flying mechanism of an eagle is very interesting. Like all the other birds, an eagle starts flying by flapping its wings. When it flaps its wings, the flying power comes from the wings’ downward strokes. That’s why the eagle’s muscles that push the wings down are significantly stronger than the muscles that pull the wings up. These muscles are so important to an eagle’s life cycle that they account for over half of full weight of the bird’s body.
Eagles control their flying speed by changing the position of the wings. When the bird wants to fly faster, the front edges of both of the wings are turned into the wind. This way the eagle tries to cut through the air, and gather more speed. When the bird tries to slow the speed, the wide surface of the wings is turned into the air, which creates a drag, resulting in slowing its body.
Eagles very often land on complicated surfaces like cliffs or top of tall trees. As sloppy landing in surfaces like these might cause severe injuries, eagles have to make sure that their landing is spot on. For ensuring a smooth landing, the birds spread their wings, and drags through air with a tall-down method. The wings work like breaks on the air, and helps to land smoothly on any surface.
Like the landing process, an eagle’s take off is quite amazing as well. When it aims to leave the ground, it receives altitude by flapping the wings. This motion causes the surrounding air to flow faster over the wings, and the bird starts to rise. At times, eagles take advantage of natural air currents to rise. If wind runs into hills or mountains, currents are forced upward. If eagles discover such a current, they just go along with the ride. This is known as slope updraft. This way the bird can fly without spending too much energy and can even go miles after miles without getting tired.
These amazing flyers do lots of flying tricks more than not, just for the fun of it. It proves that eagles are playful creatures who want to enjoy flying without any serious purpose. At times these birds swoop through air with incredible speeds, especially before getting ready to dive. This feature has turned the birds into amazing hunters. Eagles can even go in speed as high as 200 miles per hour! This is even faster than supercars, and almost half the speed of commercial airplanes.
Eagles also like to turn over, and lock the clock claws with each other to spiral down thousands of feet. This is also a mating signal between birds from opposite genders. This scene looks really beautiful, though it is really difficult to witness it from ground as it happens mostly in really high altitude which is outside our eyesight.
Why Eagles Fly in Circles
If you have seen eagles in the sky, you have obviously noticed them circling the sky. Now here is the reason behind that. Eagles try to stay inside a thermal while trying to gain height. This is a really interesting natural phenomenon.
During sunny days, earth is heated unevenly. As a result, darker areas become more warmed and the air becomes lighter. Lighter air then rises, and it is called a thermal. You can even notice thermals by observing small cumulus clouds at top. Thermals are generally seen over parking areas, large buildings, built up areas, and so on.
If eagles fly in straight lines, they will feel these thermals as bumps. These bumps can cause problems while flying, and that’s why the birds try to avoid them. Whenever eagles feel a thermal, they fly in circles to gain altitude comfortably.
Eagles do not only use thermals for avoiding bumps, but also for gaining serious height without little to no effort. In fact, eagles glide downward inside thermals. Then you might be wondering how the bird actually goes higher. Remember how thermals are created at the first place? Thermals are created with lighter warm air that goes up. In high altitude, air rises really fast. Eagles take advantage of that and glides downwards to let the air take it higher. This way the bird reaches extreme height without even moving a muscle. It is really remarkable to see how one of nature’s beautiful creations uses a natural phenomenon so effectively.
Did you know that this same method is used by humans as well? Surprised? Well, you might be, because we humans don’t have wings right? But have you ever seen an airplane? Of course you did! Airplanes also take advantage of thermals to gain altitude! Airplanes also use the same method like the eagles by gliding downwards in thermals to go higher. Even heavy airplanes can rise five meters a second if they are inside a good, strong thermal. Airplanes also fly in circles in thermals for avoiding bumps. Going straight through a thermal can cause very uncomfortable situation for the passengers inside.
Why Do Birds Fly in Circles
After knowing why eagles fly in circles, you might be wondering why birds in general fly in circles. We have often seen flocks of birds flying circles, and these are not even remotely close to eagles. But ask yourself, where did you seen these scenes of birds flying in circles? Let me remind you. Over towns? Plowed fields? Parks? Do these ring any bells? I am sure they do!
So what’s the point? Birds fly in circles exactly for the same reason explained in the previous section, thermals! Though most of the birds don’t have such long and wide wings like the eagle, most of the birds have significantly bigger wings compared to the rest of their bodies. That’s why these birds are also able to use their wings in a which takes advantage of thermals.
When birds sense a thermal, they glide their wings downwards, and start circling inside the thermal. Flying straight will take them out of the thermal and they will lose the chance to go higher without putting that much effort. Flying inside thermals does not require any flapping of the wings, and it is really easy to go higher.
Birds need to go higher for easily changing location, spotting prey, or just for having fun. So whenever a thermal is spotted, some of the nearby birds are certain to ride it. At times multiple birds spot the same thermal and try to gain high altitude at the same time. That’s why they are seen in groups, and all of them are flying in circles. This is one of the most beautiful scenes before the sun goes down.
Bird flocks are seen flying in circles in evening most often. It is because thermals are more frequently formed in this time of the day.
So, now you know the reason behind eagles flying in circles, and also the science behind this. Eagles and other birds have taught this wonderful method to humans, and by using the knowledge we are able to go thousands of miles in just hours. Observing mother nature’s phenomena is really handy, and humans have survived till date because of such observation skills.