Grey Herons portraits: preening and exfoliating

I spent several hours with these herons, initially creeping in short stages through the grass until I had positioned them against dark woodland. After a while they always ignore me, settle down to sleep and often start preening. There has to be some trust before they begin preening as they often close their eyes or position their head in such a way that I remain out of their vision. Most of these shots are full frame, some with slight trimming of the black background.