If I were you I would try planting those middles next year, apparently you are not going to combine those beans, you might go in and bush hog a row in the middle to knock the seed out on the ground ansd see if the birds come in, dont overdo it leave them standing for birds during the harsh winter months, sooner or later they will pop out, Looks to me like you do an excellent job in providing food for wildlife and unlike many people you leave it up during the harsh winter months, people around here leave a little corn standing, then harvest it the day after duck season is over....