I was wondering if anyone can give me some clues as to what might have gone wrong with my duck's failed clutch of eggs. They were naturally incubated by the duck, and it looks like all of them got to full term or close to it, but not a single one hatched. None pipped, no shells were broken. She did sit on them for a day or two at the start then off and then got back on them a day later, so they were incubated maybe 1-2 days, then let go cold, then incubated from then thru till the failed nest that i removed today at somewhere between day 31-35 or so. (These are 28 day khaki campbell x duck eggs) She also evicted (and ate) a few eggs along the way. I assumed that was because they were not viable for some reason. None of the eggs that she moved out or ate was rotten. After the whole lot had failed, she had one explode the day before she abandoned the nest (yesterday), the duckling inside looked to be mostly but not completely formed, but I am not sure whether it had deteriorated from what it had developed to, given it was rotten. Anyway, if we assume all the eggs had fully developed ducklings in them, what are the reasons they wouldn't hatch? I am guessing that they were unable to break through the membrane or shell? And if so what could cause that aside from maybe too low humidity? Could there be anything about the environment she was nesting in, (an upstairs house section of a chicken coop) or any other clues I can look for to try and figure the cause? If its relevant I had eggs from the same ducks under another chicken that hatched recently, of I think, 6 eggs, 1 pipped but was dead in the shell, 1 fully developed but didn't pip, and the 3rd was not fully developed, but mostly developed. Of the 3 that hatched, one male died at 3-4 days old of what I think was SDDS. The remaining two are a week old and doing fine so far. Are there other reasons aside from shell or membrane being too dry, hard to break through? For example could the ducklings have developed full term and the shell and membrane been normal and for some reason the ducklings were too weak, or were physically malformed in some way that meant they were incapable of pipping and coming out of a normal shell and membrane? I have tried to research this but everything I have found online is aimed at people artificially incubating and assumes I have messed up a setting in my incubator. Obviously a live duck does not have settings that one can adjust! The duck is, or would have been, a first time mother. What I am wanting to find out is the various reasons that cause naturally incubated eggs which have developed fully to not pip or hatch..