DRAWING OF HOW BABY WHOOPER IS POSITIONED 
IN EGG BEFORE HATCHING

For more information about whooping crane eggs and what happens inside, click .

From book entitled "Cranes: Their Biology, Husbandry, and Conservation"
Please cite as:
 David H. Ellis, George F. Gee, and Claire M. Mirande, editors. 1996 Cranes: their biology, husbandry and conservation. U.S. Department of the Interior, National Biological Service, Washington, DC and International Crane Foundation, Baraboo, Wisconsin. 1996. xii, 308 p.
See our online version of book!

Most of us have seen chicks hatch in cartoons or in movies. Cartoon chicks burst out of the egg, which is sitting on its large end with the small, pointy end sticking up. These make-believe chicks hatch in seconds, or stick their feet out of the egg and run around while their bodies are still in the egg. But that's not how it really happens. Hatching is hard work and takes a long time.

Inside the whooper egg, our chick is all curled up. He's been growing for almost 28 days, and now he fills up the egg. His egg is laying on its side, not on end, and the chick will hatch out of the large end. It will take him about two days.

The chick is swimming in fluid, with his tail tucked into the small end of the egg, and his shoulders and head in the large end. He's pressing against the air cell membrane, with his beak tucked under his right wing. The air cell is that dark space in the large end of the egg between the chick and the egg shell. The bulge between his legs is his yolk sac. That's the same yellow yolk you see whenever you eat a chicken egg. But a crane egg is much bigger than a chicken's and the yolk is large, too. This yolk will feed our whooper chick.

Next time you crack open a chicken egg, look in the large end. You'll see a paper-thin membrane that creates a pocket of air between the egg shell and the membrane. That's the air cell, and whooper eggs have the same thing, only larger. When our chick is ready, he'll peck through this thin air cell membrane. Then he can take his first real breath while still inside the egg. As soon as he can breathe, he can peep. We'll hear him and know he's getting ready to hatch. We'll not only be able to hear him calling, but we'll hear him tapping on the inside of the egg shell. That's how he begins to hatch, by chipping a small hole in the egg called a "star pip." It might take him 24 hours to make this small hole, chipping away steadily, using his sharp "egg tooth"--that little point on the top of his bill--to wear away the shell. That's why his head is tucked under his wing. The wing holds his beak in the right position so that he keeps chipping away at the same spot on the shell, weakening it. If his head wasn't tucked right, he would still chip away, but he might hit the shell in different places and never make that first small hole. 

Once he makes the star pip, he'll need to rest. So he'll be still for the next 24 hours, gathering strength. We'll check on him often, and make notes on his progress. After a day's rest, he'll start pecking away at the star pip, making it bigger, until it's a hole about the size of a dime. That's the "hole pip." We'll see his beak through that hole, and part of his head. And his peeping will be a lot stronger. He might rest for a few hours after making the hole pip, or he's feeling really strong, he might start "cutting out" right away. He'll chip away at the large end of the egg, literally cutting the large end off, piece by piece. To do this, he'll actually have to turn around in the egg in a circle, pecking at the shell as he goes, until he has cut off that big piece of the shell. While he's doing this, he'll be absorbing the rest of his yolk sac into his abdomen where it will feed him for the first few days of his life.

Cutting out usually only takes about an hour. It's as if the chick has decided he's had enough of his cramped shell and wants more room. Once the large end pops off, he'll kick his way out of the egg. He'll be wet and all folded up and pretty tired. He won't even be strong enough to hold up his head. But that's okay, because once he's out, all he has to do is sleep in the warm incubator. In a few hours he'll be dry, and be ready for his first meal.

Click here to ask questions about our chick or Patuxent's crane program.