One of my favourite ways to shoot Gannets is low key, highlighting the bird against any darker areas in the background, whether the cliffs themselves, or the sea below. The joy of shooting with a body such as the 5DSR, is the ability the be able to crop almost ridiculous amounts, having been able to visualise the image when first shooting, but not perhaps having the reach with your lens to do it all in camera. It helps document those calmer, more intimate moments, where the bird is completely relaxed, unaware of and unbothered by the lens pointing at it.