The chicks in the four eggs in the peregrine falcon nesting box atop a downtown Boise building are preparing to break out of their shells, the Peregrine Fund reports this morning. When I looked at the Falconcam, an adult falcon was looking down expectantly at the eggs. Click below for more info on what’s happening, and you can watch live here.
From the Peregrine Fund:
With hatching imminent, the chicks are preparing to break out of their shells. By now, they have internal organs, a circulatory system and skeleton, as well as a beating heart, feathers, and beak.
Hatching will be exhausting work for the tiny chicks, but they are developing biological tools especially for this purpose. An egg tooth is forming on the top of their beaks. When they are ready to emerge, the chicks will use this sharp structure to pierce the inside membrane and the shell. This small hole will allow oxygen to flow into the egg and fill their lungs. This stage of hatching is called “pipping.”
The adults know that pipping is about to begin when they hear the chicks vocalizing from inside the eggs.
The chicks also are developing a large muscle in the back of their necks, called a pipping muscle, which gives them the strength to chip their way out. Usually, hatching begins about 48 hours after pipping. The chicks will punch a dime-sized hole in the shell and then use their egg tooth to cut the top off the shell. A few days later, the chick’s egg tooth will fall off and the pipping muscle will disappear.