How to improve your photo
I would definitely choose this subject for an image if it presented itself. I would watch the bird and see what it was doing repeatedly, turning, preening, stretching, etc... and wait for one of those opportunities to make a capture of the bird doing more than floating on the water. Action depicts life and also adds lines in the subject to tell the story, in this case waiting for the bird to move so its lines form S-curves.
Adding a catchlight in the eyes also gives life to the subject. This can be done by adding that sparkle from use of the camera's pop-up flash. it will give a little more light to the shadowed side of the swan's face.
Include the whole reflection in the water... if a bird is in water, it's reflection is an important part of the subject.
When photographing a floating bird, also try compositions where the bird is pointing directly at the viewer and include the whole reflection and also try it in a vertical format... if the bird is in the center of the frame, make it intentional and make it appear that it needs to be in the center, making the frame vertical, will help do so. Centering in this manner will make it more majestic.