Nice bird, and interesting perch. Sharp for the SS you had - the MK IV can take ISOs higher than 500 with no problem, so don't be scared to crank it up more. I agree with a better HA, and perhaps a little lighter on the bird (not much needed, but just "feels" a tad dark). Was gaussian blur and/or NR done to the BG?
Sudhir, We would love to see you post here regularly.
I like this shot a lot. Its not easy to shoot these birds and not easy to get that blue color. Having seen the bird many times, I think your shot does justice to the blue-and-black. Very well exposed and terrific IQ. Wud love to see it posted in larger size.
Good work in difficult conditions. The blues are rich, the blacks perhaps a bit too dark. The BG looks a bit too glossy; perhaps a result of substantial NR. Minor fixes I'd consider would be cloning out the dark spot (poo?) on the perch, the shiny spot just under the thrush's foot, and the other shiny spot to the left of the bird's feet. The bright areas around the tail would be more of a challenge.