New Herring Gulls?

Today the Herrings was back on the ice at Langvannet. There have been a while since the last gulls sat on the ice, so I walked down to see what I could find. No gulls had colorings. The gulls looked also quite new. I couldn't recognize any gulls from earlier this winter. So where are these new ones from? Are they new, or are they the same as before that has moulted? Don't think Herring's are supposed to moult in February, so most likely new ones. So where are they from?