I was a hardcore twitcher. I understand why the Cocos booby has Australia’s birders in a frenzy | Andrew Stafford

Twitchers can be the subject of derision but they have greatly expanded our understanding of birdlife in the age of extinction The discovery of a black-headed gull in Geraldton, Western Australia, has put Australian birders in a bit of a flap. Normal people might wonder why, considering it is abundant in the northern hemisphere – it is the ubiquitous resident seagull in London. But twitchers, the bucket listers of birding, are proudly not normal. As a semi-reformed, semi-retired twitcher, you can trust me on this. Frankly, flying across the country for a black-headed gull is no biggie. Every year, Australian birding’s elite travel not just to every corner of the continent but our extralimital territories – Christmas, Cocos, the Torres Strait and Macquarie Islands – in search of birds to add to their Australian lists. The gull (recorded at least 10 times in Australia, according to BirdLife Australia’s Rarities Committee) isn’t even the biggest twitching frenzy taking place right now. That honour goes to our first Cocos booby, first identified on 26 May. It’s an eastern Pacific seabird that’s taken up residence on the New South Wales Central Coast. An estimated 200 tw