Incubation in total takes around 33 days. We are in the final days before hatch, however, it is difficult to predict when the birds actually began setting full time so my best estimate is that hatch will occur on or around May 6. Keep in mind this is only a prediction and so could be off. Don't be surprised if hatch begins earlier and don't panic if hatch is late!
The eggs usually hatch over a couple of days' time. Here is what to watch for to help tell when hatch is close: A day or so prior to hatching the chicks will begin vocalizing from inside the egg and pecking to work their way out. The adult birds can hear the chirping and feel the vibration and so their behavior will change. While throughout the majority of incubation they have set tight on the eggs we can expect the incubating adult to become very restless. It will get up and look down at the eggs more often, settle back down, and be up looking again within a short time.
For the past few days, incubation duty has only been done by Durand. There have even been several times when the eggs were not covered for some time. This could be a factor of the eggs being close to hatching and isn't necessarily abnormal as once the eggs develop to a certain point it is less critical for them to be covered tightly. Also keep in mind that temperatures the past few days have been unseasonably warm in Columbus and we have had a lot of sun which creates a very warm environment on the ledge and in the nestbox. Temps over the next several days are forecasted to continue to be much higher than usual for this time of the year so more than not, it will be important for the eggs to not overheat.
Hatching can happen any time of the day or night but we usually see the most hatching during daylight hours. The process will start with a pip--a small hole pecked through the shell from the inside by the chick using it's "egg tooth." It will take some time from pipping for the chick to actually come completely out of the shell.
Don't be surprised if you see Durand eating the egg shells. This is one way for her to replenish calcium in her body that was lost from her system when she produced the eggs initially. After hatching the chicks will need to be kept warm so Durand will brood the hatchlings
. This may look similar to incubation but she will actually be sitting up higher and may hold her wings out from her body more than we see during incubation.
Even though Durand (and presumably the male) have not dealt with feeding chicks ever before, the feeding and brooding behaviors are instinctual and should kick in once the adults see that the eggs are now fuzzy white chicks with gaping mouths. How to get food into the chick might be an awkward process for the adults initially but as we've seen via the FalconCam with other first time nesters, things usually turn out just fine.
Exciting times are ahead assuming all is well and the eggs will hatch. On the flip side, it is always possible that the eggs won't hatch. We'll all wait and see together!