Inconsistent hatch times

[Tinkertori]

I have a flock of free range chickens and my family is pretty good at recording the date when our broody girls start sitting on eggs full time along with how many eggs they have. Since we’ve started this though we’ve noticed that usually it takes anywhere from 23-27 days before we start seeing babies hatch. Any reason why it’s not the 21 day mark? It’s caused us to think that our broody hens had batches of dudds and quitters, but sure enough two or three days later we have a couple of babies.

 

[Ryguy3684]

Is it taking 23-27 days from the time they start sitting, or from the time the eggs are laid? If the broody is getting up from the nest alot, that cooling could cause a delay in hatching. Are they shipped eggs, or from your flock? 23 days isn't too late, but consistently 27 days probably means something is going on.

 

[Tinkertori]

Is it taking 23-27 days from the time they start sitting, or from the time the eggs are laid? If the broody is getting up from the nest alot, that cooling could cause a delay in hatching. Are they shipped eggs, or from your flock? 23 days isn't too late, but consistently 27 days probably means something is going on.

We time from the day they start sitting. These are flock eggs. Most of the broodys only get out once a day for ten minutes or so, sometimes twice on the hotter days. 27 days was the latest and doesn’t happen often. I have a current broody on day 24.

 

[RoosterML]

My guess is other hens are adding to the clutch. Any time you have a broody hen it’s best to remove the eggs and set them all the same day. Mark the eggs with a pencil or sharpie and collect unmarked eggs daily leaving in the marked ones.
I think if you do this you’ll see you’re hatching on day 20-21