Adding on to what JeanneM said, if the cage is light enough, bring them outside in it. Where i live its summer and my birds live taking a "field trip" outside in their cage. Not only do they get fresh air, but a bath from a spray bottle ( chemical free). they go crazy with it.

Make sure the lock on the cage is secure so no little birds get sneaky enough to unlatch it.

I Luv Budgies!