Possible theory on Bobwhites

[Alpine Bobwhite]

We have a pair of Bobwhites. 1 is a normal male (Alpine) and the other is a Mexican Speckled female (Maple). I think they are like a Ring-necked pheasant pair, as Alpine is rusty coloured and highly patterned and Maple as sandy coloured and speckled.
They recently took a great interest in the rabbits hutch and kept climbing in and walking around. They loved the rabbit nuggets and would do their happy eating noises when devouring them.
Alpine and Maple recently started using some of the boxes and litter-trays as possible nests, making a dip in the hay and sawdust.
We also have some cockatiels, we got them a nest box but it was small and they didn't really use it.
So we put 2 bobwhite eggs that had been lying around the aviary into the nest box, after putting it in the hutch. When the eggs were not in the box they took no interest in it. But as soon as the eggs were in there, Alpine and Maple started going into it and making quiet, soft noises and purring.
Later I put another stray egg in the box, and found that it had been pushed out. I put it back in and it was pushed back out again. I took the hint and put it somewhere else.
The same thing happened with another stray egg, pushed out twice.

So, now I come to my theory, that Bobwhites know what is and what isn't their eggs. It might sound silly and there probably is a more sensible solution but it certainly seems that way to me.

 

[Alpine Bobwhite]

UPDATE:
Okay so now that theory has been blown out. Maple pushed all of the eggs out and now she and Alpine are trying to nest in the rabbits' litter tray.
Its quite humourous to watch. Alpine practically buries himself under the straw and all the while makes the adorable little nesting noises.