Does the hen normally sit on the eggs for the entire hatching time? We have duck eggs under our hens. The eggs have external pips. And THREE times today the hens have gotten off the nest. Once for a snack I was giving the pullets outside of the coop. Once she was sitting out side the nest looking in at the eggs but not on them. And now I have no idea why this other one left the nest. They have all been broody for a month or longer. . They are in a separate pen from the rest of the flock with their nest boxes. One managed to completely escape the pen (it's inside so it's OK) but the eggs were getting cool when I just checked on them. The ducklings are still moving in the shells and have full external pips so they must be getting ready to zip now. What should I do? BTW, no incubator option just a heat lamp. Would that be better than mama getting off the nest and cooling the eggs during the hatch?