I am not sure you can ever call a bird pregnant. The process by which the egg is fertilized and formed is really fast. I think 25 hours from fertilization to laying. Not much of a pregnancy, huh?
Seems like one place said 72 hours, start to finish.
I used to have a site that timed egg development, start to finish. It's now another of those dead links. I wish they would remove them so they don't continue to show up in every search.
Here we go. This one is OK although not as pertfectly timed as the one I used to link.
Annie