If the air cell is small, the humidity is too high and the ducklings may drown - be unable to get to the cell and breathe. You can mark it on the egg shell with a pencil to see that it changes every few days and gets bigger.
If you are trying to incubate duck eggs and don't have a copy of "Storey's Guide to Raising Ducks" by Dave Holderread, I'd highly recommend that book. He spells out exactly how to incubate your eggs in great detail. Either buy it or get a copy from the library. I am glad I bought it, I refer to it a lot still, after several years of raising ducks.
If you are trying to incubate duck eggs and don't have a copy of "Storey's Guide to Raising Ducks" by Dave Holderread, I'd highly recommend that book. He spells out exactly how to incubate your eggs in great detail. Either buy it or get a copy from the library. I am glad I bought it, I refer to it a lot still, after several years of raising ducks.
