Snowstorm 

A significant snow storm moved through Minnesota on February 22-23, 2023. While this caused a lot of buzz for us humans, the storm was not a new phenomenon for Minnesota bald eagles. For birds living in northern climates, varying elements are frequent and the birds make adaptations to ensure brood success. This eagle pair prepared for the storm by digging a deeper hole in the nest - known as the "bole" where the eggs are cradled. Each adult also brought in more grasses and leaves to serve as supplemental nesting material for keeping the eggs warm in anticipation of the storm. Throughout the storm, the eggs were kept covered and were regularly turned as expected. Both adults have had a consistent diet and appear very healthy. 

Broken Egg 

On February 28, when the male and female were switching incubation duties, the male rose with one egg stuck to his brood patch. The brood patch is a bare spot of skin that all nesting adult eagles have.  It allows for the warm skin of the adult's body to be in direct contact with the egg, keeping the eggs at an optimal 99°F. We don't know if the egg was already broken when the male stood up, or if it happened earlier. 

What now? 

There is no indication the remaining egg is broken or infertile. The eagle pair will continue incubating it just as they have been, until about March 23. Since we don't know if the broken egg was the first or second egg, the incubation time frame is less predictable. We will begin egg watch on March 22. The survival rate of bald eagle chicks to fledging (successful flight) is 50%. It is sad and unfortunate to lose an egg, but since there will only be one chick to care for, the survival chances increase dramatically! 

What does happen inside of the egg?  

Here are some insights into the secret world inside a bald eagle egg: 

Once a bald eagle egg is laid, the embryo development takes off at breakneck pace! The first structure to form inside the egg is called the “primitive streak,” this will become the future head and backbone of the chick. Quickly thereafter, the embryo develops a vascular system, organs and the heart begins beating. Next to appear are limb buds, then digits. Last to develop are feathers and their associated structures and the beak. Remember, this little body needs to be ready to support itself, breathe, eat, compete with its siblings and beg for food! 35 days is not a lot of time to get all those systems in place. 

It is not hard to imagine that the first big hurdle of eaglet’s life is escaping its protective egg shell! Development takes care of preparing an eaglet for this first struggle. A sharp point grows on the end of the eaglet’s beak, called an egg tooth, and strong muscles start to move the eaglet around inside the egg. The movement of the egg tooth against the inside of the shell breaks the membrane on the small pocket of air inside the shell. This is called an “internal pip” and is the first time the eaglet inside breathes air using its lungs. Before this moment, respiration has occurred via a network of blood vessels that carry the air defusing through the egg shell directly to the developing embryo. Just before the external pip (the first visible hole in the eggshell) the eaglet still inside its eggs will begin to vocalize with tiny cheeps. We just might be able to actually hear this from inside of the egg! 

Thank you for your continued support and for watching the EagleCam!