A megapode question

A question for no reason other than I just thought of it.

Incubating eggs are normally turned by the parent.  When artificially incubating eggs (I breed exhibition poultry) it is standard practice to set eggs in a tray with round end (the end with the air cell) up, the eggs are tilted at 45 degrees and turned through an arc of 90 degrees three times a day.  Eggs set on their sides must be rotated 1/2 turn at least 3 times daily. This keeps the embryo centred in the egg and prevents it from sticking to the shell membrane. During natural incubation the embryo swings around in the egg to remain at the top of the egg and thus nearest the brood patch. 

My question is: Are eggs within the mound of a megapod turned?  If so, I assume this involved the exposure of the eggs, and subsequent turning of the eggs, by the adult.  Are the eggs "inadvertently" turned by birds digging during mound maintenance?  If eggs aren't turned then why don't embryos stick to the shell membrane?

Interestingly, megapode eggs have no air cell within the egg.  

Any answers out there?

Cheers

David Geering
Regent Honeyeater Recovery Coordinator
Department of Environment & Conservation
P.O. Box 2111
Dubbo  NSW  2830
Ph: 02 6883 5335 or Freecall 1800 621 056
Fax: 02 6884 9382



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