Ducks and diving birds have oil on their feathers dispersed by the oil gland near tail. Thus typically water runs off of a duck's back and feathers do not get wet when in water. Water pressure keeps feathers compressed against body. Very difficult to get fisheggs under feathers; plus this area is normally dry!
I will believe regurgitatation before bird transport of eggs or fry.
I remember years back I saw in a journal a scientific study about eggs and fry on bird feathers. I think the results dismissed the idea or I would have saved the article as proof that it occurs. Should have saved it anyway for times like this. .
