Need help with Duck eggs.

[RandyRhoads]

Correct.

Proper Water Loss During Incubation
As the duckling develops inside the egg there is a loss of water from the egg and an increase in the size of the air cell. If the duckling is developing normally, the air cell should occupy about one-third of the space inside the egg at 25 days of incubation (common ducks). Weight loss can also be used as a guide. Common duck eggs should lose about 14% of their weight at time of setting by 25 days