Don't know for sure the parents broke the egg, could have been attacked by crows, had a single hole in it - could have bashed against anything when it rolled. Why would it roll you ask, because Jules & Ivy were nesting on a hard flat surface with no scrape in the gravel to keep their eggs contained. And they were scared off the eggs frequently it appeared to us - not intentionally, just not a great nestsite and they were constantly on alert. As for the other two eggs, the article is a bit wrong ... the eggs disappeared and we assume they were "disappeared" either by the parents (like Trey & Princess) because they were not viable OR because a crow or something similar got to the nest, spooked off Jules/Ivy, got the eggs and poof. As I said, not an ideal nest location!! I think the "parents took them" was a cross-over from the Radisson story where Trey or Princess removed one egg after about a week of incubation. No worries though, it's nice to have a great piece like that.
One thing that is actually two related things is that the bottom photo isn't of Ivy, its of Jules and I really wish they had identified the photographers. I gave them the middle image but the first was taken from our photo gallery and is a photo taken by Pam and the bottom was taken from Dennis' photo gallery. The photo I provided that they didn't use was one of the chicks, which is one they asked for specifically but hey. What bothers me more is that none of them have photo credits. I will email to see if they will add them and will let you know how I make out.