They really can be hard to expose properly. You might experiment with curves in RAW to get the right balance between highlights and shadows. Here I would crop a bit off the top and apply some S/H for the part of the chest that is not sunlit.
Question here is what kind of metering are you using? For this image you should have used spot metering and meter the bird and use -ve exposure comp.
That will yield your white and blacks right.
I think the exposure on the bird looks pretty good here. For me though I am not a fan of the water in this image. If you can try to get these guys where there are some nicer colors reflected in the water or out where the water colors are all blue (as reflected in the sky) I think you'll have a much better overall image.