I’m reading “The Trumpet of the Swan” now, and it describes the female swan laying five eggs over the course of about a week. However, they all hatch over the course of one day. Is this accurate? How could eggs laid a week apart converge developmentally so that they hatch only a few hours apart?
The eggs are laid one at a time, but left at ambient temperature until they are all laid - at this point the parent birds start sitting on them to incubate them and thus they all develop at more or less the same time.
When the embryo is in the very early stages of development, it is quite tolerant to cold conditions (for this very reason).
Thank you, ignorance fought.