High Speed Bird Photography

I've been working on mastering the technique of hummingbird photography. I finally have a complete set of speed flashes, which enables being able to stop the wings in flight. These shots utilizes the Tamron 150-600mm lens and set of four Yongnou YN560iv Wireless Speedlites powered down to 1/64 power. These images were taken early evening. I want to try again mid-afternoon when there ambient light, so I can slow the flashes down to 1/128 sec. 

Yellow-Throated Warbler

Downy Woodpecker