Something That Casts Shade Can Be Vital
With smaller flocks, shade is a logical choice to cool the flock as it is cost effective and simple to set up. a 4x8 sheet of plywood on sawhorses can offer ranging birds a place to get away from the radiational heating of direct sun.
If trees are not applicable, considering awnings and other roof extensions that will shade the inlets to the house. Each of these structural changes will enhance cooling without undue higher cost.