Crows...my arch nemasis
They're tricky animals. If you get too close to them, they'll send up an alarm call and alert every creature in the neighbourhood! The best thing to do is like someone said earlier, get to a field where you know they feed really early before sun up, plant some decoys, get hidden and wait for them to land. Try to stay hidden as long as possible or as soon as they see you they'll never let you get hidden again.
Good luck!