Hartlaub's Gull

Well there you go! This beautiful gull is right where it should be!

Thanks, @Ava for the ID :)
and my apology, checked my records, picture was taken from Cape Town.

My only concern about the ID I just left for you is that your map says you spotted this on the east side of SA, and these gulls seem to be more on the west side. Anyway, it's a place to start investigating ID.