they will attack at some point wether its the first or last batch. Firstly, don't take them to the same place again, take them further so they get a run at the area and secondly the next toss take 2 batches, let one go in the morning and the other go in the afternoon.
We have tried all times of day, they start coming without problem and then bang they come back split up and in pieces.
It is a great idea for clubs to get eagle owls but if they are released the RSPB will shoot them and if they are just flown as captive birds near nesting sites who is going to train and look after the owl?
Phil