Great Blue Flasher | Sunning Great Blue Heron (Ardea herodia… | Flickr

Sunning Great Blue Heron (Ardea herodias) - Ritch Grissom Memorial Wetlands (Viera Wetlands), Melbourne, Florida

This is the sunning pose that Great Blue herons will sometimes assume after preening.

Sunning is thought to be a way to expose the bird's feathers to UV light from the sun to aid in destroying fungi and help to rid the bird of parasites.

Though to me it looks like he's [flashing] me!

It's also called delta-wing posture.

What is this grey heron doing? It stayed in this position for at least 15 minutes. : birding