Birds don't have vaginas and anal tracts. They have only one opening for everything: the cloaca. Pee, poop sperm and eggs all come out of that same opening. I just had a hen die from being eggbound. Here are pics of the autopsy where you can see developing eggs of all sizes.
Uhm, they do have what is sometimes called a vagina inside the cloaca, as well as a separate intestine that opens there as well.
here is a link to a diagram (very graphic): http://www.ansci.wisc.edu/jjp1/ansci_repro/lec/lec1/female_images/images_label/chickentract6.jpg
both open into the chamber, and are obviously controlled so eggs do not come through the feces.
I also found some posts on egg bound here as well... I really hope I never have to deal with that...
I generally know what I am talking about.
I do a lot of research.
I saw other diagrams that don't use teh exact same terminology.
But anyway, now we know, and I seem to see that the eggs come from above the intestine, not below it.
Birds are not the same as mammals, LOL
Last year was my first time raising birds from chicks...
I plan to raise a few more next year.
Would like to get some easter egg chikkinz...
6 from the 9 non broody girls. And people say phoenix chickens are bad layers. Okay, okay some are mixed serama too but still they are very consistent.
The far left egg is a "fart egg" as I saw it referred to elsewhere on the forum (LOL)
and the other eggs are all from Isa Browns - as you can see varying from smaller to double yolkers (on the far right)