Loose Emilia

import Data.List     as L
import Data.Sequence as Q

data Bird = Azure | Black | Carmine

main = interact $ unlines . map (show . Q.length) . L.filter onlyAzure .
                  L.unfoldr bellRing . flip Q.replicate Azure . read

bellRing Empty = Nothing
bellRing w@(first :<| w') = Just (w,w''') where
  w''' = case w' of _ :<| w'' -> w'' >< endOfLine
                    Empty -> empty -- I HATE YOU STUPID EDGE CASE
  endOfLine = case first of Azure -> fromList [Black,Carmine]
                            Black -> singleton Azure
                            Carmine -> Q.replicate 3 Azure

onlyAzure w | Azure :<| _ <- w, _ :|> Azure <- w = True
onlyAzure _ = False