BBB,
If the pup is chasing birds just think how he will be, when he comes across a rabbit or Hare - you may lose him!
Sounds like basic training needs to commence and I would suggest a Gundog train book to get the basic obedience started. Even better many Gundog societies are starting training classes that you may want to join. An untrained spaniel becomes an embarrassment and many shoots are plagued by them!