This morning the peregrines started the day with a few clouds, wind from west at 10MPH and temp at 38F.  The forecast for the day ahead calls for partly sunny, with a high near 54. West wind 7 to 13 mph, with gusts as high as 24 mph.

Around 6:40 AM, the female was seen actively calling for the male.  Shortly after, the male was seen swooping in flight outside the nest box.  The female raised herself up, rambled to the edge of the nest box, then departed, likely for a bathroom break and a bite to eat.  The male entered the nest box and assumed incubation duties!

Let’s take a further look at embryonic development and what happens around day 5.

The embryo uses oxygen and disposes of CO2. Both have to be transported from and to the embryo. In the first 2-3 days the early embryonic germ layers (ectoderm, mesoderm, and endoderm) in the blastoderm are just few and so oxygen can be obtained easily. But as soon as the layers increase the embryo needs an infrastructure within the egg for the oxygen, nourishment and protection.

The 3 extra embryonic membranes are formed from the primitive germ layers within the egg. Everything needed for the development of the embryo is on board of the egg. Water, nourishment and energy like fat are there for tissue growth and everything needed to maintain the process. The only things needed are warmth and oxygen. On the 5th day of the embryonic development:

* The somites extend to the tip of the tail.

* The toes begin to form.

* The allantois is visible coming off the hindgut.

* The allantoid circulation is commencing

* The Erythropoiesis starts in the yoke sac

* The embryo starts to move with head and neck region

* The amnion strats to contract

* The proteinase is starting

Literature cited: Veldhuis, Froona, Embryo: the first four days, Sept. 8, 2008, 

http://falcoperegrinus-froona.blogspot.com/2008/09/embryonic-development-day-5.html