Incubation provides the heat needed for embryos to develop inside the eggs of ducks and geese. Because the required temperature range of developing embryos is narrow, parents must commit to a rigorous incubation schedule...
Female waterfowl periodically turn and manipulate eggs within the nest to maintain close contact with the brood patch and to promote even heat distribution. Eggs in the center of the clutch are closer to the female's brood patch and consequently warmer than eggs on the perimeter. To reduce temperature differences among eggs, females shift them within the nest so that each one can be directly exposed to the brood patch. [...]
For approximately four weeks, females incubate their eggs in relative silence. Then, one or two days before hatching, clicking and peeping sounds are emitted from the eggs. Small cracks appear on the surface of each egg as the hatchlings strike the shell using their egg tooth—a tooth-like accessory on the bill that falls off shortly after hatching. Vocalizations by the young help synchronize hatching and assist with imprinting because they stimulate vocalization by the female. The hatchlings finally emerge from the eggs after about 3 to 24 hours and dry in a few additional hours.
~ John M. Coluccy, Ph.D., & Jennifer Thieme
So this is basically about female ducks but we’re all envisioning gander!Peeta doing these things, right? ❤