Western kingbirds are noisy, aggressive, obvious birds that breed across much of western North America.  They can be identified by their chattering calls, 'kingbird' posture, gray head, yellow breast, black tail, and narrow white outer tail feathers (a key field mark for separating this species from the similar Cassin's kingbird).   I took most of the pictures at the San Jacinto and Hidden Valley Wildlife Areas near Riverside at the Salton Sea in southeastern California.   The bird in the bottom image was attempting to subdue a large grasshopper at Valentine Wildlife Refuge in Nebraska (it eventually succeeded and swallowed the grasshopper whole; thanks to my friend Dave Rintoul for taking us to Valentine!).
            This page has a few images of western kingbirds in flight.