Besides making sure the feeders are topped up, make sure they have access to water or they will wander off.. Use some bales of straw with corn rubbed in will keep the birds interested.
If there are any lengths of tin sheeting on the farm, make some little shelters in the woods for the birds, this can be easily done by 2 bales of straw with the sheeting laid across..
A good book to buy is The Complete Book of Game Conservation, Fully revised 3rd edition, by Charles Coles.. Don't pay more than £20 for one of the auction site,,