Blog # 390 Hatch Watch!

Orpheus is about to incubate. 

This is the beginning of Hatch Watch… Faint peeps from within the egg will be the first sign hatching is  about to begin. These ‘peeps’ are the embryonic chick’s way of communicating with its siblings and its  parents from inside the egg. These faint “care–soliciting” peeps prompt the adults to turn the eggs more  often, build up the nest sides, and spend more time incubating. Camera footage from yesterday clearly  showed this heightened interest on Ursula and Orpheus's part.  

Osprey eggs in our area require an average of 36–42 days of incubation with rhythms that depend on the  weather and their care. This spring’s seasonal weather was chilly and rainy but not enough to harm the  embryo by rotting the eggs. To ensure normal development, Osprey eggs must be rolled frequently to  maintain them at a uniform 98–99ºF and to insure the embryos develop normally. Ursula’s first egg was  laid on April 16, making today Day 36. 

Over the years, Orpheus’ incubating style has changed. Females incubate the eggs and tend the  nestlings during the night. However, during the day, males usually give their mates meal breaks and at  other times. In 2013, Orpheus’ first year as a mate and father, he would only incubate in Ophelia’s stead  during mealtimes. Each year since he increased his incubation time, demanding at least a third to a half  of some days. Last year, he began pushing Ophelia off the eggs so that he could incubate, which he  continues to do with Ursula. This year with Ursula, he has been incubating at least half of the daylight  hours and is very demanding when he wants egg-sitting privileges. 

What triggers the embryo to start the hatching process? As hatching approaches, the embryo is so large  that it nearly fills the entire egg and starts to retract the residual yolk into its body cavity. Until this point,  the embryo had been respiring using the chorioallantoic membrane (CAM), diffusing O2 in and CO2 out  

through the eggshell and the CAM as illustrated below. However, the embryo’s oxygen demand increases  along with its growth and activity while oxygen supplies from the CAM run short. 

Cross-section of a bird egg showing the CAM and air pocket, courtesy of Brainly, Inc. 

The shortage of oxygen triggers the embryo to start lung respiration. The embryo instinctively puts its  head under its right-wing with the beak pointing toward the membrane separating the egg contents from  the air pocket. A few days before hatching, the embryo pierces the inner membrane and starts lung  ventilation in the air pocket. This is called internal pipping. Even though the first lung respiration has  started, the CAM remains important for respiration for a few more days.  

The embryo instinctively puts its head under its right wing with the beak pointing toward the membrane  separating the egg contents from the air pocket, courtesy of Raising Happy Chickens. 

About 12 hours after it pierces the inner membrane, the embryo starts tapping the eggshell repeatedly  with its egg tooth, a sharp, white, chisel-like temporary structure on the top of the beak. Repeatedly  tapping the same spot in the eggshell eventually causes the shell to weaken and break. This is called  external pipping. 

Pipping is exhausting. The “pipping muscle,” a neck muscle used to make this specific movement, bulges  by the time the embryo has hatched. From the outside, a small star-shaped crack or hole in the eggshell  appears 2–3 days before hatch day, sometimes with the point of a beak sticking out. After external  pipping, the embryo takes a rest.  

The embryo has one last challenge ahead—breaking free of the eggshell, which can take another 12  hours after external pipping. The parents typically watch as the embryo cuts the blunt end of the eggshell  with its egg tooth, turning inside the egg while using its wing for direction and legs to apply force. Once a  near circle is cut, the embryo tries to push itself out of the egg stretching its legs. This causes the last bit of the shell cap to break loose, allowing the embryo to push itself free. New hatchlings are wet, tired, and  vulnerable. Hours after hatching their down feathers dry and become fluffy. After they’ve recovered from  the hatching process they become more active.  

Hatchling resting, courtesy of Landings. The pointed white egg tooth can be seen on the top of its bill. 

The parents will watch as the exhausted hatchling struggles to remove itself from the confines of the  eggshell and dry off in the air. The newborns are semi-altricial (semi-helpless) at birth and unable to  thermoregulate their body temperature. (Precocial species are completely developed when they hatch, whereas the altricial birds have more development to complete.) The hatchlings are capable of limited  motion, have their eyes open, and are covered with down at birth. However, they can beg for food in a  matter of hours and instinctually know to defecate over the side of the nest and may try to do so on Day  One.  

You can tell from the mother’s behavior when an egg has hatched. From the moment the first egg  hatches, Ursula will no longer leave the nest to eat. She’ll stay with her precious brood and will not leave  for several weeks. You will also see the parents staring at the inside of their nest as if they were admiring  something.  

Eyes to the sky! 

Candace 

Candace E. Cornell 

Friends of SaltPoint, Lansing, NY 

Cayuga Lake Osprey Network

  

HELP PROTECT OSPREYS: 

• Eggs will be hatching soon. Stay 300 feet away from nesting sites during the breeding season.  If the Osprey vocalizes, you are too close! BACK OFF IMMEDIATELY. 

• Carry binoculars to view wildlife from afar. 

• Help keep local waters clean, healthy, and safe. 

• Recycle used fishing lines, twine, and nets, which can kill Osprey. 

Join the Cayuga Osprey Network and volunteer to help monitor Osprey nests: cec222@gmail.com

EYESTOTHESKY! 

WATCH! 

Salt Point Osprey Nest Cam 

READ! 

OnOspreyTime: Ospreys of Salt Point 

VISIT! 

Cayuga Lake Osprey Trail