theirs no rules to it....theirs a generally excepted rule that its all released before its respective season starts. how ever i always had a few pens of partriges out all season as call birds. and a shoot i know that shoots BIG days restocks at the start or december with brailed birds.
HAVEING to let birds go on the day of the shoot is something that is simply not on yanks and spannish may do it but we dont, any keeper who makes up excuses for it needs gone. keeping birds put is easy if you know how. we used to put 2,000 reds 2000 ducks and 14,000 pheasants down on just over 300acre and ge