Large. From the way it was behaving, I think it is a juvenile.
No interactions present.
This is an adult, not a juvenile (these have all-feathered faces, and will not be out of the nest yet). There is a big rookery in the Castle Grounds, the only one in the islands, I think. See http://www.virtualheb.co.uk/rook-hebridean-birds-western-isles-birdlife.....
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
Yes, large rookery in Castle Grounds. There are several large black birds in the area! Ravens and Hoodies I know. This was taken about 300 yards from Castle grounds.
Lat/Lng: 58.2148, -6.3866
OS grid ref: NB424335