mama goose not sitting on egg all day

[sourland]

Most geese cover the eggs with down and nesting material before they leave the nest. This serves to retain warmth in the eggs. Hens of all breeds can spend significant amounts of time away from the nest without any impact on the viability of the eggs as long as temps are not extremely cold.

 

[NanaKat]

Then why is it so difficult to hatch goose eggs in an incubator? Doesn't the humidity have to be maintained at a higher level than chicken eggs....