Since you can seldom compete with the 8,000 acres around you that they will forage, I would focus on filling gaps. Early, drought, and late are the times they need resources. It doesn't hurt to fill some other times as well. Early sources for pollen (which they are usually desperate for) would be pussywillow and red maple. Crocuses don't hurt either. Drought on into late is filled well with chicory. Asters, goldenrod and smartweed are great for late as well. A variety of clovers is always good. White dutch, white sweet, yellow sweet, hubam, purple prairie, aslike, ladino, crimsom. Plus birdsfoot trefoil, anise hyssop, mustard, dandelions, hairy vetch and any fruit trees. Other good trees: basswood (linden), Black locust and tupelo.