Earlier Sandipan Ghosh has posted same species from the same location Gajoldoba, Teesta Barrage. I took the boat ride on 7th & 8th Jan 2017 and posted Bean Goose photograph before.

Here is a take off shot of Common Merganser flock of female.
exif : f/8, 1/2500, ISO-500, F-length - 330mm with Canon 70D & 100-400 II handheld.
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