The Mystery of Birds' Eggs
What are the egg shells made of?
The egg shell consists of a protein matrix that is deposited heavily with calcium carbonate and small amounts of some other minerals. Calcium comes from the food eaten by adult females, but also from their bones. In fact, up to 12% of its bones may be drained! The cochlea is porous, allowing the exchange of gases through its pores. Warm up and oxygen while carbon dioxide and steam escape.
How do eggs form?
The egg begins in the ovary and makes its way down the proliferative assembly line where it is added to what it is. The layers of albumin, membranes, microbial layer and shell occur as the egg moves along the conveyor belt until the egg is fully formed. Contrary to popular belief, egg yolk does not become a chick but serves as a source of nutrition, especially fat, that feeds the growing fetus and continues to feed the chick for a day or two after hatching. Do you know that the Easter belly has a round appearance? This is the last of the nourishing yolks that gradually disappears as they are absorbed and processed by rapidly growing birds. In contrast, the albumin or "white" consists of proteins and contains the germ layer and other essential components that will become alive.
Self-sustaining life support system!
All that is needed for the growth and survival of the chick is designed in the egg itself, and all the necessary ingredients in addition to the gas exchange mechanism. All parents need to add is constant control to prevent breakage or predation and steady supply of warmth. Custodial parents provide warmth through the patch of hug on their abdomen. They also turn eggs every eight to sixty minutes, (depending on the species), twenty-four hours a day! As you can imagine, the egg must be strong enough to bear the weight of the foster parent but not so strong as to prevent the appearance of the chick when it is ready.
Colorful eggs like Easter?
Although eggs come in a variety of colors, they are not intended to attract attention. In fact, the opposite is true. A well hidden egg has a greater chance of avoiding predation. Eggs are more common than open-nosed species, such as shore birds, so eggs merge with the substrate and can not be easily seen by ordinary observers. On the other hand, there are likely to be clearly colored eggs such as white eggs from some swallow and ducks, or bright blue of the propane, in protected nests.
Color is created in the uterus where the small pigmented glands secrete pigments that originate from two main sources: bile or hemoglobin. If the egg moves, the color may become tight or dotted. From time to time, environmental factors are known to cause abnormal colors or a total absence of color.
Small as a hummingbird or as big as an ostrich?
In small species, egg weight may include a large proportion of body mass. For example, a miniaturization egg is approximately 13% of body weight. By comparison, the equivalent of a 130-pound human female means having seventeen lbs. Oocytes may lay eggs up to 22%, which translates to the same woman with a child of twenty-nine pounds!
Larger species may lay eggs which are just two or three percent of their body mass.
Birds are very light to maximize flight efficiency so carrying any extra luggage can be a real challenge. For this reason, ovaries are initially present most of the year, where they fall back into small organs when the hormones are extinguished after the breeding season. Imagine if the birds were carrying young birds and had to fly with the developing children in the womb! It is doubtful that they will leave the earth! The egg laying cycle is very short. Once fertilized, the egg prepares for rapid deployment, so that the female is as weak as possible.
Egg synchronization
Eggs are not placed on the same day. The interval between each egg can be as short as a day or up to eight days. Despite the delay, some species eggs hatch on the same day even if it is placed over a whole week. For example, ducks need to carry all their children on water immediately after hatching, so it is important to get out of the crust in a tight time frame, regardless of when they are placed. This is called synchronous thatch, which can be achieved by delaying early egg incubation so its growth will coincide with the eggs laid later. If the egg is cooled during the later stages of incubation, the development will stop and the fetus dies.
For other species, asynchronous spawning is preferred. Many birds of prey and birds of prey benefit from this style. If there is a lack of food, the chicken that hatchs first has a better chance of thriving. Late late or late older siblings often die. However, if the old chick dies, the younger ones still have a chance to become strong so that nothing is lost to the parents.
Young chicks
Chicks can be seen by chance and can differentiate between day and night. Most species hatch early in the day to allow at least some good meals before dark. Night types will do the opposite.
It may take hours or days for the egg to hatch completely. Chicks have physical properties to help them achieve this: white teeth at the tip of their necks and necks that are disproportionately large. All features are lost within days of hatching!
It seems that each species knows exactly when to hatch, and usually coincides with the appearance of their favorite food. (For example, the rodent crop of prey birds, and the mosquito crop of grafts). Once they hatch, the parents will destroy or remove the shells, and sometimes even eat them to help restore calcium values.
Stay tuned for more articles about the amazing wildlife world!
Diane Wittner is a wildlife biologist and founder of the Alberta Wildlife Conservation Institute. This article is approved by North Bird House, an online store for bird lovers. A percentage of the proceeds are donated to the Institute each month.
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