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M15 & F23 continue their dedicated duties to incubating their eggs. Egg1 will be 35 days on 12/13 and Egg2 will be 35 days on 12/16. Hatch can happen anytime from 34-39 days after an egg is laid. We are all anxiously awaiting the appearance of a PIP in the egg signaling that hatching is in progress. The eaglet works hard to break out of its shell and the process usually takes 24-48 hours.
What is a PIP?
The initial hole in the egg is called a ‘pip’. By the time a pip is noticed the chick has already been working for a while inside the egg to break out. One definition of pip: A spot or speck.
One definition of pip: A spot or speck. The origin of the word as it is used in this instance is English. As a noun it also means a small shape or symbol. As a verb - (of a young bird) crack (the shell of the egg) when hatching. There are other uses of the word too; to include: small hard seed in a fruit; spots on playing cards, dice or dominoes; single blossom of a clustered head of flowers; diamond-shaped segment on the surface of a pineapple; a star on the shoulder of an army officer's uniform (British). Hence the reason they are sometimes called 'Star pips' on the eggs.
What is the hatching procedure?
Close to hatch time, eaglet repositions itself inside the egg, bringing its beak close to the air space at the end of the egg. It will absorb remaining yolk into its abdomen & begin absorbing remaining fluid in the egg. The chick will move inside the egg into a tuck position - beak between its body and its wing - which increases pipping efficiency.
The embryo pierces air space & will breathe by its lungs for the first time. The hatchling has a calcified egg tooth (falls off shortly after hatching) located on its upper beak to break through (pip) the shell. The hatchling also has an enlarged muscle (pipping muscle) used to brace the head as the egg tooth scrapes across the shell while it rotates in a counterclockwise direction using its legs - eventually breaking a small hole in the shell (pip, sometimes referred to as a ‘star pip’).
Prior to beginning to hatch the young bird absorbs all of the remaining yolk. The yolk is fat-rich and provides the chick with much needed energy. The digestion of this fat also provides a source of metabolic water (water created as a by-product of the break-down of fat).
Here is more detailed information from Nick Fox's book Understanding the Bird of Prey (Hancock House, 1995): "By about 55 percent of the way through incubation the membrane surrounding the embryo and the shell membranes fuse and the embryo, no longer free-floating, becomes fixed inside the shell. The egg is now unevenly weighted and if placed on a smooth surface or floated in warm water will tend to roll back to a fixed alignment. Thus the turning movements of the parent at this stage do not rotate the egg but simply free it from the friction of the neighboring eggs for a moment so that it can roll back toward its equilibrium position. In other words the turning tends to maintain the eggs in relatively fixed orientations, not to rotate them randomly as in the first half of incubation. This is important for attainment of the correct hatching position.
"As incubation progresses further, this equilibrium position becomes more obvious and if the upper surface [of the shell] is marked it can be seen on candling to coincide with the furthest drawn down part of the aircell [I.e., the air sac just inside the shell at the blunt end of the egg, between the soft membranes--as the embryo becomes fixed in position, the aircell shifts from the blunt end toward the top of the egg above the chick's head]. The first slight pip of the shell normally takes place a little to the left of this line at the edge of the aircell and it is possible to predict and mark the exact spot where the pip will occur several days beforehand. A well-positioned pip is a good indicator that the chick itself is positioned correctly. As the pip progresses and the egg-tooth is raised higher, the first actual complete hole will tend to be further to the right, on the equilibrium line itself. When the chick starts to hatch properly the break up will continue right-handed around the blunt end of the egg.
The parent sits assiduously but lightly on the eggs at this time and is very attentive. This reduces the chances of the egg membranes drying up and yet guards against crushing the eggs. If the hatching egg is turned hole downwards, the chick will start cheeping in distress. This call stimulates the parent to poke the eggs around until the egg rolls back upright, otherwise the chick risks suffocation."
Thank you SWFEC, hosted by Dick Pritchett Real Estate, for providing & maintaining suitable trees & environment for this Bald Eagle Family. www.SWFLEagleCam.com @SouthwestFloridaEagleCam
Thank you to Dick Pritchett Real Estate (SWFEC), Church of the Nazarene, Eagle Landing & several friends for allowing me to film on their premises.
And thank you to my 'spotter'.