This one is especially good in cornrows or if you are without canine assistance. When you get into a spot where you suspect a bird is holding, even a large general area, stop walking every dozen yards or so and just stand for 15-20 seconds. This is usually enough to panic an otherwise cagey bird. When you stop, they think you've spotted them, and instead of holding they flee. Doing this even when you think there are no birds around might suprise you, because there always seems to be one hiding.