is there a way to tell a chick has died in its egg around day 16?

Not sure but I would just leave them alone.

 

If the veins look defined and normal, I would leave it in the bator for a few more days. It might be a late hatcher. You can also candle and look closely at the air cell. If there is a dark area in the air cell, then your chick has most likely internally pipped. Place the egg against your ear and listen for peeping or tapping. While candling or listening, lightly scratch the egg with your fingernail to encourage movement.

 

In most cases where the chick dies this late is because the humidity is to high and the chick has drown. Another factor is that the temp may have spiked.

 

Quote:if the veining is still defined, then the chick is still alive. it's when you candle and DON'T see the blood vessels then you know it's gone. the dark area is the chick, and sometimes it might be too large to discern movement later on in incubation... when it gets closer to hatching then you might see movement in the air cell as drawdown and internal pipping occur.

Pete55 has an excellent article on incubation, https://www.backyardchickens.com/forum/viewtopic.php?id=491013 and you might want to look at some of his other posts as well, because he's got a number of good threads on incubation, hatching, air cell problems, etc. the link i posted, there's a lot of info on that one specifically. you might want to bookmark it for future references.

good luck. my eggs went in the 'bator on the 30th (2 days, 19 to go)