How many tiels could I put in a 30"x18''x18'' cage? Right now my cage set up is : 2 tiels in one 30"x18''x18'' , My budgie pair in another 30"x18''x18'', and 5 budgies in another 30"x18''x18''. I got a spare 30"x18''x18'' and another cage that is 24'x16''x16'' and 2 smaller cages .I'm building an outdoor aviary for my budgies soon but not until after I get my 4 new tiels so my question is should I buy another cage? Or am I ok with what I currently have ? All opinions/criticizing is appreciated.