Like its cousin, the eastern kingbird, the western kingbird is a type of flycatcher. They eat mainly insects which they catch on the fly. They prefer open habitat, where they can hunt for insects, but require some trees bushes or man-made structures where they can perch and ambush their prey.
The range of the western kingbird has continually been expanding eastward over the past century, and now includes most of the US west of the Mississippi River. This has put them in conflict with eastern kingbirds. Both eastern and western kingbirds are fiercely territorial against other kingbirds, especially when nesting. The range of the western kingbird has expanded so greatly that you can now find western kingbirds wintering in southern Florida.