is this image too tight? Do you notice anything that is not right? Almost FF longitudinally. I had to add a sliver of canvas on the left.. hard to add more I think.
I had to compose as such... this bird came out of nowhere when I was photographing wigeons the other day and i like the dark BG, which BTW I had to do some cloning on the right to get rid of an OOF bird ruining the effect...
7D, 1/3200, 500mm @ F/7.1, ISO 800, HH on my belly.
Many people favor a little more room in the frame, but every so often a subject just comes close enough that your only choice is a tight frame. That gives the opportunity for more pixels on the subject, and more of a portrait-type image. I think this is a very nice image and the strong dark BG gives it a somewhat unusual or different effect, and for me that pairs well with the tight frame. I like the low POV and nice reflection.
I might take a little more off the top, and if there is more clean reflection on the bottom, consider including more there as an alternative.
I'm not that experienced with bird photography but I often see suggestions about removing a second catchlight.
Enrique I do sometimes like to see full on birds in the frame but I must admit this does look very cramped which is a pity because I do like the BG and the water.