Doves and pigeons have very dry feathers and a lot of dogs don't like to hold them. The conditioned retreive (force fetch) will help with this along with about a hundred birds. If you can get a cleanly killed or dispatched pigeon (or two) and freeze it, I use them after the dog is conditioned to "Hold". Once they've learned to hold a dumbbell, then a bumper, then it's time for the pigeon. I take the dog through each step in force fetch with the dumbbell first, then the bumper, then the pigeon. Then we work with clip wing pigeons.
It takes time, that's why it's called conditioning.
Also make sure you offer a lot of water with these birds, because they are so dry. If our dogs come in with a mouth full of feathers we clean them out and water them before we let them go back again.
Good luck. I am sure he'll come out of it.