A skua seen from the Halicat off Sydney on 11 March 2006 was identified at the time as (probably) a South Polar Skua. I was made aware of this record recently, after a South Polar Skua was seen off Sydney in April 2011 and asked for my opinion. Looking at photos, I believe that the 2006 bird was actually a juvenile Brown Skua. When I mentioned this to a few of the original observers I struggled to convince them verbally, so I prepared a brief discussion paper with some images of the subject bird and some of a juvenile South Polar Skua I photographed in Antarctica in 1994. I think this discussion paper has broad relevance to the identification of juvenile Catharacta skuas in Aus. Hopefully, the link below will allow it to be downloaded as a pdf from the SOSSA website. Thanks Brook for the IT support!
Discussion Paper Sydney Skua 2006