Remember that the birds still count towards your bag limit if you can not retrieve them. Also, be sure you make a reasonable attempt at retrieving the birds, otherwise it is considered wanton waste.
A good thing to do is have one person stay at the 'blind' and mark where the bird goes down and the other person go to that spot. You can keep a visual on the location you last saw the bird. Often times when you both walk to the spot you can lose the actual location and then you might end us searching for awhile. Wait until the first person arrives and then the marker can go help. Doesn't always work, but I have found it to be a relatively effective way to retrieve birds when they fly 100 yards and then fall.