I don't think we've ever talked about egg rotation during incubation.  Female bird parents, at least the songbirds nesting in my bird houses, rotate their eggs frequently during the incubation period.

So why do birds rotate their eggs?  The obvious answer would be to evenly heat the egg while the female parent is sitting on the nest.  However, doing some research, I learned it is much more complex than just heat distribution.  Developing chicks need to "float" in the middle of the egg shell.  Keeping the embryo afloat ensures it gets enough albumen to fuel its growth, and prevents the embryo from sticking to the shell.  I will never cease being amazed at the details of our Creator's design!!

Meanwhile, we wouldn't be human if we didn't study this design at its smallest detail.  Here's a link to a short Audubon article about a study conducted on egg rotation -- artificial eggs inserted in a nest and outfitted with sensors.  Incubating Bird Eggs is More Complex than you Think

In the photos, you will see a nest of Eastern Bluebird eggs in different positions over a 30 minute period.