One year I was hunting alone late season in the snow with a Brittany pup. We flushed over 60 birds from a small cattail slough in a pasture, they spooked way ahead and didn't get any shots. Most of them went one direction towards a public area so I followed hoping to pick up a straggler or two. There was about 6 inches of old snow with an inch of new snow on top that had just quit when I started hunting. The pasture was pretty bare, but there were little clumps of cattails here and there and after walking a couple hundred yards, started to see some fresh tracks in the snow. The tracks would go a few yards and then disappear in the clumps. About that time the pup would smell them and go on point. I had to kick around and the bird(s) would get up at my feet. We put up at least 25 or so birds one or two at a time. I could have shot them all, but probably wouldn't have gotten any if I hadn't noticed the tracks or she had smelled them. Point is if you see birds flush ahead, go to where they flew and look for fresh sign. Certainly some will run ahead, but some will stick tight to where they land and you literally have to boot them out.