After posting this message on Cape Gull and reading in SASOL that the Kelp Gull has a whitish eye, I noticed that the gull posted by HoepHoep in her "Tsitsikamma 2006" trip report
displayed a light eye. I emailed the photo to a friend of mine to see if he could maybe positively ID it as a Kelp Gull.
It does however not seem to be as easy as looking for an pale eye.
He sent me this photo of a "Cape Gull" showing a pale eye and also included some text by Trevor Hardeker that appeared on SABirdNet a couple of years ago.
Photo taken by Tertius Gous in West Coast National Park on 11 September 2004.
(I included an enlargment of the eye of the bird - click the image to enlarge)
Text by Trevor Hardeker
Larus d. dominicanus
(nominate Kelp Gull) occurs in Australasia, South America, Antarctica and on most of the subantartic islands. Larus d. vetula
(aka Cape Gull) is an endemic subspecies (currently considered for full specific status) to Southern Africa. Most books dealing with seabirds cover both of these as subspecies at least. Nominate Kelp Gull also occurs as a vagrant in Southern Africa, with recent records coming from the west coast near Cape Town and the Eastern Cape.
Superficially, differences are that Kelp Gull has a pale eye (beware that some Cape Gulls can show this feature, but Kelp Gull's eye is generally smaller), a smaller more rounded head and a slighter bill. Other suggested differences, although not cast in stone yet as far as I am aware, are that Kelp Gull has a narrower white tip to the tertials and slightly more yellower legs.
Peter Ryan wrote an article on these two gulls in AB&B about a year ago (I can't remember the issue number) and the latest issue of Birding World (one of the top U.K. birding magazines) has a detailed article on the identification of "Kelp" Gulls covering both dominicanus
As far as web resources go, try the excellent "Gull Identification Website"
which covers the ID's of all the world's gulls in some detail. This site is very useful for all gull watchers and for learning more about the possible gulls that could still occur in SA. Martin Reid's gull website
is also well worth a visit, if you are interested in finding out more about gulls. Both these sites have lots of photos.