My lot do it in a spare nest box too! I just now have it as a litter box! Clean shavings in there at the bottom of the aviary! Don't know why but thts just what they have always done ! X 
Hi Sarah, just interested how you keep the nest box clean, for awhile Asriel and Hermione were using a spare nest box for a toilet and it quickly got all horrible, i tried cleaning it but was no good so had to remove it.
But what do other chips do when they go to the loo in your aviary's do you have a box. for them to soil in !
The Dilutes now have a litter tray and do use it sometimes but not always, some of them probably the babies are using a corner by the door for the toilet and of course i always end up with dirty hay on my head when i open the door. My Bailey and Abigail in my other aviary use a litter tray and they are very good, it does make cleaning their aviary easier.