Plucking the birds may not be practical in the middle of a hunt but warm birds feathers pull out easier than after they have cooled. When plucking in the field make sure you understand the local and state laws as some states require the feathers on one wing to be left in tact. Have a cooler with ice available to put field dressed birds in as soon as possible.
When plucking examine the bird for age. The age of some foul will determine the best cooking method to use to attain the highest quality end result. If the plumage is not fully colored or you notice a lot of pin feathers the bird is probably young. Long pointed spurs (pheasant, turkey) mean the bird is probably older as rounded spurs are found on younger birds.
Remember that if you are going to hang the bird leave the skin and feathers on.
If an upland bird is badly shot it may have to be skinned rather than plucked as its skin is much more delicate than that of water foul. It is always better to leave the skin on by plucking as the skin helps keep the bird from drying out when stored and in the cooking process.
A strong flavored bird like a sage grouse, fish eating duck, and sea duck may need to be skinned due to their strong flavor.
In rare instances ducks may have parasites in their breast which show up as white rice-like grains. These parasites are harmless when cooked thoroughly but it is best to discard this meat.