Hummers... there is an elderly lady in SE New Brunswick that has hundreds of hummers coming to her feeders near the Tantramar Marshes. She uses 3:1 (never that store bought crap with the dye in it) and she uses 2:1 (and stronger!) near season end as the young ones build strength.

4:1 is good... unless you want to lure hummers from you neighbours. >;-)