DNF laid her second egg today at 2:49 PM nest time. When will her eggs begin hatching? I took a look at our records and saw an interesting variance between 2021 and 2022, although she laid her first and second eggs on the same day both years. In 2021, her first egg hatched on March 25 and her second egg hatched on March 27. In 2022, her first egg hatched on March 27 and her second egg hatched on March 28.
I haven’t dug into the weather yet, but I’m guessing that 2022 was warmer than 2021. Bald eagles don’t delay incubation like peregrine falcons do, but they spend a lot more time off their first one or two eggs when the weather is warm enough to allow it. Suspending or slowing embryonic development means that all of the eaglets will hatch around the same time. Bonking will still happen – it’s the eagle way! – but the battling babylets will be more evenly matched, size and development-wise, if they hatch within a day or less of one another. I’m predicting March 26 and March 27 for hatch, but we’ll see what happens!
In the meantime, DNF’s first egg is a little over 72 hours old as I post. The embryo might look something like a layer cake if it was big enough to see. It has organized into front, back, top, bottom, and left and right sides, and is growing a circulatory system and cardiac cells. Deep within the egg, its heart is beginning to beat.