The adults seemed to be intermedius, or at least one did.
Bird A:
Adult, quite dark mantled in direct comparison to Great Black-backeds. Probably intermedius, though subspecies identification is difficult.
Missing primary 3. This day had fog blocking hazy sunshine.
Bird A
Bird B:
Adult, quite dark mantled in direct comparison to Great Black-backeds, but not quite so dark as Bird A. Seems possibly to be intermedius, though subspecies
identification is difficult. Missing primary 4. This day was overcast. The last photo, by chance, also contains Bird A!
Bird B
Bird C:
Third summer. This day was bright overcast.
Bird C
Bird D:
First summer. This day was overcast, some fog.
Bird D