I had similar problem with my 17 month old golden pups. Early on they retrieved fine, this fall when it came to doves and geese they wouldn't retrieve either. Sent them to a trainer for 2 weeks and they have greatly improved. He advised that you have to be careful always being the thrower. They associate only bringing something back that you throw. He used a launcher as part of training program and seemed to be the ticket for them. He also used dummys with pheasant wings attached. I use my daughter to throw items for them now, to retrieve, while I have them at heel walking or sitting. He also taught me to have them sit and stay and walk up 20 feet or so and throw dummy. Go back to the dog and walk it at heel away from object and then bring them back to sit, sometimes I go 30 yards back. I order to fetch and have them bring it back. I will use frozen pigeons for the feather effect. Also to always end with fun retrieves, no rules, Get them excited, tease them with dummy and then throw it. Once they get dummy get very animated, happy loud encouraging them to bring it back. So far so good I have had them back about ten days from trainers and they have been doing well. I will let you know more after I return from SD next week whether this solved my issues.