Some cool video from earlier today of the pipping process of one of the eggs. The parents do know they have a hatch in progress now, so they're pretty excited, while taking care to keep turning both eggs and incubating them but switching places a few times more often than usual and taking even more care how they place their feet and beaks as they take their turns checking hatch progress. No rest for the weary tonight.
The parents won't interfere with the hatch but they do need to know when there's finally a chick in the nest instead of two eggs so once pipping begins there's less rest for both parents. This is a familiar phase in rearing of their babies, so they may also remember that there's a long night ahead without the usual snooze time. Can be hard to catch a fish in a lake or river at midnight... time to stock up, so they may make extra forays before dark.
A hatching chick makes noise with its beak scratching against the shell to abrade a larger opening after the initial external pip, and it will also chirp while it tries to break out of the shell. The shell has thinned somewhat during incubation due to intake of its calcium content by the chick during its developmental process.
Hatching activity itself is driven by lack of oxygen and rise of carbon dioxide in the shell after the tiny external breakthrough or pip; that change in ambient air inside the still largely intact shell causes hatching contractions as the chick strives for more air, rotating as it probes the shell with its beak and pushing with its legs, resting between efforts.
The parents must look after their own needs before the hatch, after that there's a little time (several to 12 hours) before the chick will beg for food.
And after that.... it's a zoo of meeting perpetual demands for food, housekeeping and babysitting until a nestling's wings grow strong enough to start exercising them and venturing into branches above or adjacent to the nest structure.
Even after fledging, an eaglet must learn to fly well, where to fly to in order to catch their own food, and it needs to be shown how to hunt successfully. In the meantime the parents continue to provide some food while encouraging independence of the fledgling(s), which of course would rather be fed than have to make their own way to nail down some elusive chow that's still on foot or swimming or on the wing itself.
