I had the opposite challenge here, relative to the exposure issues with the Storks and Egrets. This birds are quite dark, and were generally flying across dark backgrounds (the Park is a bit limited in terms of where you can set up to shoot, so I didn't have a lot of flexibility here). They also didn't come that close, and this represents a smaller crop, explaining less detail in the eye and beak than I'd like. Canon 100-400 with Canon 1.4x II Teleconverter at 435 mm, ISO 200, f/8, 1/640 second, Wimberley Sidekick/Arca Swiss Ballhead/Gitzo Tripod (manual mode, manual focus).