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Thread subject: The chick and 'HATCHING'
Name Date Message
Marie 05/14/05 12:32 pm I was checking out my Ornithological.( Proctor and Lynch) book this am about hatching.
I quote,
'" At the end of its development within the egg the hatchling begins one of the most strenuous events of a birds life.-hatching from the egg.Throughout the develoment of the embryo the egg steadily loses water through transpiration through the chorioallantois membrane. Because of this water loss and the loss of the yolk fats metabolized during development, the egg is much LIGHTER at hatching than when it was LAID. The eggshell, too, is THINNER than when it was laid down because the chick has absorbed much of the CALCIUM from the inner shell lining, but the shell still represents a substantial barrier to the hatchling. The chick also faces several major physiologic hurdles before hatching.Most critically, it must shift from respiring via the chorioallantios to breathing with its lungs. the chick takes its first breaths of air in the air space within the shell as it struggles to break free. It also absorbs the remaining yolk sac into the abdomianl cavity and begins to swallow any remaining amniotic fluid before hatching..
Two specialized structures found only in hatchlings aid the chick in its struggle to break open the shell. A small sharp egg tooth develops on the tip of the upper beak; the pre-hatchling rasps the inner shell wall to weaken the surface, repeatedly extending its head to drive the the egg tooth against the wall. A substantial enlargement of the complex muscle ( the hatching muscle) at the chick's neck helps brace and cushion the head as the chick forces the egg tooth through the shell( Bock and Hikida 1969). After hatching most of the fluid within the complexus muscle is reabsorbed and the muscle continues to function as a head extender in most adult birds. The egg tooth is lost in the weeks aftet hatching"
WHEW.......hope you got all that and can understand why the ospreys are being more delicate as they settle on their eggs....
CHORIOALLANTIS MEMBRANE = the highly vascular membrane between the developing embryo and the shell that facilitates both respiratory and excretory systems for the chick. The blood vessels of the choriollantis carry oxygen from the shell lining to the embryo and bring back carbon dioxide to the shell surface. This inner shell lining acts like a large , passive lung.
Well that is your lesson for this morning...... ;)
Marie 05/14/05 12:43 pm Just a little 'egg' trivia...

The air space I alluded to where the chick takes its first breath, seems to enlarge during incubation It is thought to provide the chick with in the egg its first opportunity to breathe air. This space is situated at the big end of the egg.The chick apparently first breaks into this air space within the shell as it struggles to crack the shell and hatch out.
I also read somewhere that the chick calls to its parent from inside the egg and can take as long as five days to break out of its captive world. Perhap, NO. chick has started its journey already and chirps occasionally to its parents causing them to peer at their eggs.(not sure which bird that was that took five days to enter its new world)
FOB Webmaster 05/14/05 02:21 pm The first year we had a camera on an eagle's nest (it wasn't on the website), we had a female eagle incubating three eggs.

She got to about 40 days, and suddenly she just got up and left. The pair didn't return, and the eggs were left for predators.

We think she never heard their calling or felt any movement, so she gave up because she assumed they were infertile.
Nancy L 05/14/05 02:22 pm Thanks, Marie - That was some great information. So I guess maybe one or two of the chicks are starting the hatching process as we write!
Tiger 05/14/05 02:24 pm Let us hope that the chicks are reading this! :) :) :)
Cecilia 05/14/05 02:28 pm Thanks Marie and Lisa! From this info I'm wondering if that same airspace is what you see when you peel a hard boiled the egg never fills the shell, there is always a gap on one end? Perhaps that was the air space for the chick that never got to develop? Very interesting. Thanks for taking the time to pass this on.
Celeste 05/14/05 07:15 pm We learn something every day! Thanks Marie!
RonS 05/15/05 11:05 am Thanks, Marie. As always, timely and useful. It dawns on me that, due in large part to your tutorials, I now much more about the osprey's body that my own.
Marie 05/15/05 11:58 am Well Ron..stay tuned.........Sunday's tutorial coming up soon.... is good to know more about other life forms as it keeps one from being egocentric or dare I say it...narcissistic. That is NOT a reference to how I see You Ron. They are just two fancy words that seem to fit in with my thoughts for the moment... ;-))
RonS 05/15/05 12:23 pm Oh, Marie. I'm much too humble to think you were referring to moi!! LOL
Marie 05/15/05 12:28 pm LOL....get to your lesson for the day, young MAN.... ;-))
cathy 05/15/05 07:21 pm Actually, I win most humility contests as being the humblest person on earth.
Marie 05/15/05 07:55 pm Hi Cathy.......good to see you posting...;-)
It is ' watch and wait' time for all of us now.... hence the info...
Have you seen any action with the ospreys in your area.
cathy 05/16/05 10:41 am Hello Marie and all - I have noticed a pattern in our region that Ospreys return to the Duwamish (in South Seattle) in April, and apparently different osprey return to the North part of the city at a similar time, but we do not see them over our bay until June or July. We see several eagles flying back and forth (mature and immature) in March and April and then they are scarce for the rest of the summer. I think it may follow a pattern of fish in the bay for the osprey combined with the need to feed the chicks. For the eagles, I think they are "dating" when we see them and then they stick close to their nests when we don't see them. I'll start noting the dates.

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Tom Throwe
Last modified: Sat Feb 18, 2006