This morning, again, clear skies, bright sun and temperature at 43°F.  The forecast calls for lots of sun, with a high near 70!!  Light southwest wind increasing to 6 to 11 mph in the morning.

At 5:39 AM, the male had been incubating the 4 eggs.  He lifted himself up, and off the eggs, walked over to the edge of the nest box, looked out for a moment, and returned to incubation mode.  He then spent  quite a bit of time doing his normal shuffling and adjusting on and around the eggs.

So let’s continue with the fascinating notes on embryonic development, and look at day 12:

* Three rows of feather germs are visible on the tail.

* The nictitating membranes (inner eye lids) begins to form.

* The egg tooth begins to form.

* The bone marrow cavity of the femur begins to form.

Until now the skeleton is made up of cartilage. The proces of ossification is beginning from day 12. Ossification is the process of bone formation, in which connective tissues, such as cartilage are turned to bone or bone-like tissue. The ossified tissue is invaginated with blood vessels. These blood vessels bring minerals like calcium and deposit it in the ossifying tissue. Bone formation is a dynamic process, with cells called osteoblasts depositing minerals, and osteoclasts removing bone.[1] This process, termed bone remodeling continues throughout life.

Literature cited: Veldhuis, Froona, Embryonic development day 11-14, Sept 15, 2008                                                                                                                                                                      http://falcoperegrinus-froona.blogspot.com/2008/09/embryonic-development-day-11-14.html