Greg's comments about exposure are correct, but in looking at the image, over-exposure is not quite what I expected. How did you manage the exposure for this image? I have a reason for asking, but I will defer posting my thoughts on the exposure until I have a better understanding of how this was done.
Regarding composition, I have a couple of thoughts. My first thought is similar to what has already been suggested: crop the second bird (in the background) out of the image. I was thinking in terms of a square crop initially, but in so doing, I then noticed the reflection of the swan's neck at the bottom of the image.
I accept that within the constraints under which the image was captured, you may not have been able to capture the reflection of the full neck and head of the swan, and if that's case, well, ok ...
But if that had've been a possibility ......
Just a thought for you to consider.