The Bald Eagle

 By: Sandra Pfeffer

I am at my Prime! It is time to settle down, find myself a mate and start my own family.

As I soar through the sky, looking for some fish to feast on, I spot a male, perched on a branch. I quickly asses what to do first, do I grab some food or try to impress this male?

The decision comes quick. I am hungry, and it is getting colder. I need to feast first and then, I'll fly up and impress him. Who knows? Maybe this winter, I will not need to spend it alone. 

My eyes are capable of seeing fish in the water from several hundred feet  above while I soar through the sky. 

My eyes have an inner eyelid called a nictitating membrane. Every three to four seconds, the nictitating membrane slides across my eyes,wiping dirt and dust from my cornea. It also helps that it is translucent, I can see through it while it is covering my eye!

My Talons are sharp, and very powerful. They are backed by tremendous muscular force from my legs. The tendons of my lower legs tighten, bringing my talons closer together, allowing my talons to lock and secure around a catch!

I spot a salmon, and dive in for the kill! Thankfully my talons have rough, small projections called spicules. These help me secure my dinner, so that it does not slip from my grasp.

I swallow my salmon whole, and store it in my crop. The crop can be used to store food for a while, especially when food is scarce. The crop is located in my throat. It is also how we store indigestible parts of animals. Whatever we cannot digest we spit out in pellet form. 

When food is abundant, I will gorge myself, and store food in my crop. Once my crop is at its full capacity of 924 grams of food, I can fast for several days. If the prey I have caught is too big, I use my beak to tear it into peices that I can swallow whole because we cannot chew our food. 

I have a high metabolic rate, meaning I must consume more food in proportion to my size. I even consume the bones! My strong stomach acid digests the bones, and I can get the calcium that my bones need to help with their development, as well as use it in aiding in the formation of eggshells.

Speaking of aiding in the formation of eggshells, I should really fly back up and see if I can impress that male perched on the branch. With my wingspan of 7 feet, I can fly in high altitudes and they help increase my lift. I should be able to win his heart in no time!

Time to put my syrinx to work! That is just the fancy name for my voice box. I will call out to this mystery male and fly around him. We eagles mate for life, so that means this male will be my mate till death. 

Before I know it, he is off his branch and we begin to pursue each other. We rapidly dive and follow each other in a chase. He then flies upside down underneath me! I've heard about this move. He locks his talons onto mine, and we begin to cartwheel at high speeds towards earth. As we approach the earth, just before we make contact with the ground, we release each other and fly up to the branch he was pearched on earlier.

He has won over my four chambered heart. Our circulatory system is a closed system much like in a human.

Now, we must agree on a place to build our nest. We gather branches and materials and decided on a thick branch high up in a tree, close enough to the water so we may be able to get food. 

Since we fly really fast, it sometimes feels like we may get cold, but our circulatory system keeps our body at 106F,  keeping us comfortable. When we are resting, our body temperature is 101F during the day and 105F at night.

We are both 4 and a half years of age, and you can tell this by the color of our plumage. Our heads and tails are white and our beaks are finally yellow. When we are younger, our feathers are darker, and our heads are dark as well. Our beaks are almost black when we are younger. 

I call out while perched on a branch. It is time to mate, and start our new family. He jumps on my back, making sure his talons are tucked away so that they may not hurt me. Our cloacas touch, and sperm from his cloaca enters mine. Within a few days, I am with egg!

I have finally laid an egg! The start of our family is underway. My nesting patch has already developed. A nesting patch is an area on the lower breast that has lost the feathers and is richly supplied with blood vessels. This makes it easier for me to transfer heat to the egg, and since both male and female eagles share the incubation period, the nesting patch is also present on my mate as well. 


The incubation period will last an average of 35 days. During these days, we turn our egg every hour to ensure that incubation is evenly spread. If we do not do this, the embryonic membrane might adhere to the inner shell of the egg, and that can be fatal!

We also take turns incubating the egg. when one of us goes in search of food, the other takes over and patiently waits for the other to get back with dinner! Incubating an egg is a full time job!

The embryo in the egg is also able to breath! The embryo breathes a little different than we do though. In the prenatal respiratory stage, the gas exchange occurs through diffusion between the external environment and the chorioallantoic membrane. 

The paranatal respiratory phase is the hatching. This stage is during the last 2-3 days of incubation. The baby eagle's beak will penetrate into air pockets between the inner and outer shell membrane. At this point the lungs begin to take over the chorioallantoic job of gas exchange. The final stage is postnatal and that is when the beak finally breaks the shell of the egg. 

Oh my! What was that sound coming from under me? Is the egg finally hatching?

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