I would even add, if you have the time get tho the field where you saw them before sunrise. Set up in a ground blind, get a chair and get comfortable. Listen and watch. Then you can tell where they are entering the fields. You might even find they are roosing in the same woods as that field. Maybe not. Before you just blindly start walking around in the dark, use the owl call to make sure you don't spook them off the roost. This should be useful to identify their locations.

Think of the ground blind as a recon mission. You may be able to even video them. Either way you will learn more about the quarry.