Calcium

Do you give your birds enough calcium?  The best source I have found is ground oyster shell, however there is another option for free calcium that you can add with your oyster shell that the birds will love. 
When you cook something with eggs, instead of throwing out the shells, wash them out and put them in an airtight bag and freeze them.  Once you have enough, then take them out and turn your oven to 325 degrees. 
Get a flat baking pan and cover it with parchment paper or foil.  Parchment paper works best. 
Then with the shells in the sealed bag, use a mallet or a rolling pin and crush the shells.  Then spread the shells out on the pan covered in parchment paper.  Try not to make it too thick.
Bake the shells for about an hour or more, longer if you have a lot of shells. 
Take them out and while still on the parchment paper, use the rolling pin and crush them further.  Make sure to make the pieces very small, same size as the oyster shell.
Cool the egg shells, bag them up and distribute to your birds as needed. 
My birds love it and I'm not throwing out something my birds can use and saving money too. 
Hope you like this hint, Beth