Some years back I started researching a way to improve the meadow pasture so that the chickens were getting more protein out of their forage. I started frost seeding white dutch clover in certain areas of the meadow and also planting the clover over garden rows after the harvest to cover the ground and also give them fresh clover in the fall. The clover can have up to 22% digestible protein, depending on the time of year and time of day, even.
Another thing I did was to leave all the fallen leaves around their coop alone and go farther afield when raking leaves up to store for their deep litter in the winter. These leaves provide hiding and growing places for bugs, worms, and grubs they can easily find, even late in the fall.
I also took old hay bales and old loose hay and left them at the edge of the meadow/forest up by their coop so I could move them now and again....under these would be scads of earthworms, bugs, etc.
My mother is old school and likes to keep the lawn mowed very short all the time, but I encouraged her to let her grass go to seed more often in certain areas so that the birds could glean the seeds and also so that the grass could reseed itself to greater thickness and health. Now she will do this, especially in the early spring and also again in the fall...the pics you see above are showing the birds eating not only the bugs but mostly the grass seeds.
Planting and creating more foraging opportunities can improve even a small area of free range. This can also be done in a small way in a coop and run situation using deep litter, grow frames, bales of hay, old stumps, and even cardboard on the ground.
Here are some pics of the chickens grazing the white dutch clover...
These next few pics are of my broiler chickens out on range...