I know a man who spends a lot of time at his local sewage works. No, he doesn’t work there: he’s an ornithologist specialising in gulls.
He reasons that gulls just love dumps, tips and sewage works. Indeed, they are generally present in these mucky places and find the pickings much to their liking. But this man is looking for rarities – gulls from overseas which occasionally find their way to Australia.
There are only a few records of rare Sabine’s gulls, Franklin’s gulls, blacktailed gulls and one or two others which have wandered to our shores. Lucky the birdwatcher who first spots such a rarity.
Our Sydney gull – the silver gull – is well known to all. It’s the gull on every cricket outfield. Like most gulls it’s not just found at the coast but just about everywhere including the very centre of our vast country.
There are two other resident gull species in Australia: the pacific gull and the kelp gull but both are uncommon in the Sydney region. But our man in the sewage works isn’t looking for these.
Black- headed gulls are probably the most likely rarities among the gull species to find their way to our country.
My field guide to the birds of Australia claims the species is a ‘vagrant; mostly in n. Aust and WA, perhaps becoming regular at Darwin’. Black-headed gulls are attractive birds and seem to be the northern hemisphere equivalent of our silver gull. The birds are about the same size and have similar habits. Both have silver backs and wings: the latter tipped black. The major difference is that the black headed gull has a chocolate brown hood when in breeding plumage. I’m always reminded of a hangman when I see one.
The blackheaded gull’s distribution has increased. During the last century it colonised Iceland, Greenland and parts of North America. It now ranges across Western Europe to Japan and further south. It seems therefore likely that my field guide could be right. Black-headed gulls could be headed this way. And the man at the sewage works could be the first to see them.