During my last outing I took a different approach and positioned myself high on a ridge. I sat there quietly in my truck for about three hours, listening to the night sounds around me. But instead of just letting my recorder roll and listening with my ears the way I have in the past, I took advantage of the quiet (I was out solo) and plugged my headphones into my recorder.
The difference was like night and day. I had my mics positioned up on the roof of my truck, pointing in two opposite directions. I sat comfortably in my driver's seat and listened through the head phones. The mics and recorder functioned just like a bionic ear and pulled in all kinds of faint sounds that I wouldn't have heard using my own ears.
At one point I heard a weird moaning sound, kind of ghostly, somewhere out in the forest. It might have been an owl, but at the time it was certainly a weird sound to hear. And soft stick cracks emerged from all around me as twigs dropped from trees and deer/rodents scurried about.
So if you haven't tried this approach, give it a shot next time you go out recording. When you're sitting quietly, it makes a world of difference (but the noise would probably be overwhelming if you tried this while walking). I used ear buds, and they worked pretty well, but over the ear headphones should do better, if you have them.