But when an egg is fertilized, a baby bird grows inside until it’s big and strong enough to hatch and meet the world!
Anatomy of an Egg
In between the eggshell and the egg white, there are two membranes (inner and outer) that provide more defense against bacteria that may have slipped in through the shell. These layers are made of keratin; the same protein that makes up human hair.
The next component of an egg is the yolk. Contrary to popular belief, the yolk is not what develops into a baby bird if fertilized. The yolk contains less water and more protein than the white, some fat, and most of the vitamins and minerals of the egg. These include iron, vitamin A, vitamin D, phosphorus, and calcium, among others. This allows the yolk to be a great source of nutrition for the growing baby bird. Just like the eggshell, the color of the yolk varies depending on the species of bird!
Developing Baby Birds
After an egg is fertilized, the embryo starts developing. On the yolk, there is a very tiny white spot called the embryonic disc.This is what then turns into a baby bird. The amount of time it takes for the bird to hatch depends on the size of the adult bird. For the rest of this blog, we’ll be discussing the timeline of a chicken egg!
In the first few days after an egg is laid, the embryo is microscopic and looks nothing like an adult bird at all. On the fourth day, amniotic fluid will surround the embryo, protecting it and allowing it to move around inside the egg. At this stage, the chick will begin to look less like a blob and more like a bird. Eyes are the first to fully develop. At the end of the first week, the chick’s neck thins out and allows the head to become visibly separate from the rest of its body. The beak also begins to form!
When the chick is in position, with its beak pointing to the air sac, it is ready to hatch. The first thing the chick must do is “pop” the air sac so it has enough oxygen while it works it’s way out of the shell. From there, the chick uses its wing and legs to maneuver itself around in the shell. Using the egg-tooth, the chick will peck at the shell in a circular motion until it reaches a weaker spot.
However, those membranes are very strong, and are hard to break through. But these baby birds are tough! They will continue to peck at and push against the shell until there’s a hole big enough for its head to poke out. In about 12-18 hours, the chick will have pushed its way completely out of the egg and is ready to take on the world! It’s not very cute at this point because it’s still slimy from the fluid inside the egg, but once it dries off the chick will be very fluffy! A few days after hatching, the chick’s egg-tooth will fall off as it is no longer needed.
Here’s what you’ll need:
- An empty milk jug, one-gallon is the perfect size
- Popsicle stick or wooden dowel
- Decorating supplies! Stickers, paint, etc.
Keibel, Franz. “Ten Stages of the Developing Chick”. Released into the public domain. Uploaded on 4/15/17 from wikimedia.org
“Chick and Shell; Black Background”. Released into the public domain. Uploaded on 4/15/17 from publicdomainpictures.net
Egg and birdhouse images property of Discovery Express Kids LLC.