I noticed the bullseye pattern in the eggs of one of my hens, which would indicate that it had been fertilized.
I only have three chickens, each with a distinctive egg color, and live in the city, so there are no roosters and never have been.
(Unless magic happened and my male duck could somehow fertilize an egg)
I have an incubator to hatch my duck eggs, so I've saved that hens eggs for a few days now and am going to experiment to see if they will develop at all.
Most of the research on parthenogenesis in birds was in the early 60s and 70s, and almost all about turkeys and quail. I can't find any current research on it at all.
Anyway, we shall see.
I'll keep a detailed log including photos of candling.