What a great shot. The grain is not at all problematic.
This was at the falconry show at Hohenwerfen Castle (south of Salzburg), September 2016. A vulture landed on the lawn about 30 feet from me and was headed my way. I was glad I was not a mouse.
I was shooting at ISO 1000 due to all the motion, so it is a little grainy. Plus it was on my old D7200.