Baby Birds and How They Hatch

Spring is here, and that means birds all over the world are getting ready to make a nest and lay their eggs! You might have seen a nest in a tree, or perhaps you’ve participated in a spring egg hunt to find colored eggs hidden outside. Before a baby chicken grows in an egg, you can harvest the eggs to be cooked and eaten!

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

The first part of an egg that you see is the shell. Egg shells have very diverse appearances, depending on the type of bird that laid it. Chicken eggs, for example, are white or brown. The American robin lays bright blue eggs with brown speckles. The surface of the shell is bumpy and grainy, due to the thousands of little pores that allow air and moisture into the egg. There’s also an outer coating on the shell, called the cuticle, that keeps out dust and bacteria to keep the baby bird healthy as it develops.

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. ​

An air space forms when the insides of the egg cool and contract after it’s laid. The air cell usually rests between the outer and inner membranes at the egg’s larger end, and it accounts for the crater you often see if you’ve eaten a hard-boiled egg. This air cell grows larger as an egg ages.

The egg white is also known as the albumen, which comes from albus, the Latin word for “white.” Four alternating layers of thick and thin albumen contain approximately 40 different proteins, the main components of the egg white in addition to water.

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!

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During the chick’s second week of development, its claws and feather follicles form. An important structure begins to grow: the egg-tooth. This sharp little cap on the tip of the beak helps the chick peck its way out of its shell when ready, in a process called pipping. In the last week before hatching, the chick continues to grow until the egg white is completely gone. At this point, the chick will be covered in down, small fluffy feathers that insulate the baby bird as its outer feathers grow.

Pipping

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.

Build Your Own Birdhouse!

Now that we know all about baby birds, it’s time to make a safe place for the adult birds to build their nests and lay their eggs.

Here’s what you’ll need:

• An empty milk jug, one-gallon is the perfect size
  
• Scissors
  
• Popsicle stick or wooden dowel
  
• Decorating supplies! Stickers, paint, etc.

Step 1:  A little over halfway down the milk jug, cut a medium-sized circle in the plastic. This will be the opening for the birds to enter and exit their house as they please.

Step 2:  Make a tiny puncture about an inch below the holy you just made. Then, carefully slide a popsicle stick or wooden dowel into the opening and secure it with glue, if necessary. This will serve as a branch for the birds to perch on!

Step 3:   Decorate! Make this birdhouse your own by adding whatever decorations you want to the outside of the milk jug. You could paint it (with waterproof paint), glue foam shapes to it, add stickers, or just about anything else. Place your finished birdhouse outside and wait to see if any of your neighborhood birds decide to call it home!



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References:

http://www.thepoultrysite.com/articles/1459/embryonic-development-day-by-day/

http://www.enchantedlearning.com/subjects/birds/info/chicken/egg.shtml


Image Credits:

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.