Hi Sanjeev- An amazing bird. I like the portrait showing the long neck although maybe not quite so much is needed on the bottom. The bird is fairly well lit despite the very harsh light. Is this a heavy crop? It seems the image quality is not what it should be and this could be the issue. Regarding your techs, if you used ISO 400 you could have stopped down to f8 and halved your shutter speed to 1/1280s, both of which would help with IQ, especially if you were at 400mm.
I love the background flowers, this is beautiful. John is right about the ISO I never use 100 too restrictive on exposure techs note his comments.
What was the time, the light does seem harsh. Might be an opportunity to use a filter or choose better light. The composition is alright, maybe a tad tight and some off the bottom. Take a piece of paper and place on the screen and play with different options. I like what you are doing with subject placement,..moreover the vert framing is great - that was well done.