Saunders offers Keeley a cigarette. Keeley says he doesn't smoke; it bothers the birds. He tells Saunders if he's going to smoke, stand off to windward. Of course, if you want to avoid getting smoke, you want the smoker to your leeward.
The mission is for the squad to escort Sgt. Keeley and his homing pigeons so that the pigeons can fly over German troops and equipment, taking pictures with a special camera attached to the pigeons. Keely has many pigeons, but only 1 camera.