DEC 9: Bald Eagle brood patch

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DEC 9: Bald Eagle brood patch

This post was updated on .

On the assumption that the first egg was deposited on Saturday, November 30, the 5 week incubation period should produce the first eaglet on or about January 4, 2020.

Phil writes and provides his photo (December 8): I was at the nest this morning at 9:30. The female was perched on the tree at 208 and the male was in the nest, down low. I noticed in this photo, you can see her “Brood Patch”.

Here is a link to another photo of the fully exposed brood patch from the Minnesota Bound blog 

"We all have heard and most of us have used the term “brood patch” as we enjoy and learn from watching our favorite eagle pair during their nesting season.  The brood patch is an area on the breast area of the bald eagle that develops shortly before the female lays the eggs.  The hormonal changes cause the feathering in this area to fall out leaving a patch of bare skin.  In the brood patch area there is greater water flow and some swelling to allow the blood flow to warm the larger area. The increased flow of blood in the area creates warmth for incubation.  Both the male and the female bald eagle develop a brood patch, but typically the female’s is the larger as she assumes more of the incubation duties.  The brood patch helps insure the eggs incubation temperature is maintained at 99.5 degrees Fahrenheit!"

Click on this link to view the photo