The birds tend to hang inside the refuge zone often, cruising up and down the river. If you get new birds in, that is your better opportunity as they aren’t quite familiar yet with the lines like the “seasoned” birds are that hang down there. Crappy weather will be your friend too as it seems to get them scattered sometimes and they don’t always fly their normal, daily routes. You must study and know the boundaries well and need to scout it out during daylight hours.