There are 3 ways of teaching hold.....
1. Hold
2. Force Hold
3. Force Fetch
Hold is the easiest to teach you just keep putting the bumper in the dogs mouth and command hold till he will not let it go until commanded to release......
Force hold has the same concept as hold u just are applying some type of pressure " force " to get the dog to understand that u want him/her to hold the bumper until command to release......
Lastly is Force Fetch.....FF is a combination of the two ( hold & force hold) but takes it a step or two further.... FF is the foundation used for teaching pile work which in turn teaches the blind retrieve....
I would recommend that u purchased fowldawgs I,II & III. By Rich Stawski.... Very inexpensive way to teach yourself how to train your retriever.......
As for the birds.....I would go get yourself some live pigeons and clip there wings then let them go for your pup..... He'll figure it out on his own.......FYI... just don't over do the live bird because if you do he/she may not want to go back to the bumpers.....

"First off, you've gotta be smarter than the dog!! " "That leaves most trainers out......"