@hank & or Rovio in general,
Just some general feedback but 6 or 7 room boss levels (mainly in the daily challenge, however sometimes in the normal levels) are beyond stupid and an obvious grab for cash from Rovio.
Most boss levels require 1 (or 2) birds to first clear the path, and then usually between 1-3 birds to kill the boss. So that is a minimum of 2-3 birds just on the boss, let alone getting through the previous 5-6 levels.
Time to rethink that imo Rovio, or at least better disguise the obvious grab for cash by using gems to get additional birds!