All my aviaries lie on paving slabs and I have concreted between the slabs and along the sides to ensure the little nasties can't visit.

 

RE the lime, it's about 1cm thick and is covered by a 3-4cm of sand.

 

I am running an experiment in 2 aviaries, one with lime & sand and one with sand only.

 

What I am noticing is that in the one with lime & sand, the budgies do rummage around but they're not digging down to the lime. Off the top of my head I recall Kaz saying that you'd have to consume 1 kg for it to be toxic .... I don't know how much it would be for little budgies.

Ikg for a 60kg human equals 1 gram for a 60gram budgie

Ikg for a 60kg human equals 1 gram for a 60gram budgie

 

So, it's just as well the sand layer is thick