Question: when does a sparrow excite more birdwatchers than an eagle would? Answer: when it's a white-crowned sparrow from the United States, hopping around in Norfolk.
Hundreds of twitchers have been thronging the village of Cley Next The Sea to see the extremely rare visitor, which has only been seen three times in Britain before, and never in southern England.
Theories for its arrival include it being blown off course by gales, or hitching a ride on a ship. But whatever the reason, it appeared this week in the garden of Richard and Sue Bending, who moved their bird feeder into the road, with the sparrow following, so watchers could get a good view. And they have been doing so – in throngs.
"You might say this is a once-in-a-blue-moon bird," explained Brian Unwin, a birding writer who keeps a record of rare arrivals. "Turning up in Norfolk,it excites more interest eventhan an eagle would. If you're a British birdwatcher you can go to Scotland and see golden eagles and white-tailed eagles fairly easily, but to see a white-crowned sparrow you'd have to travel to North America."
The bird presents a particular attraction for "listers" – birdwatchers keen to increase the list of species they have seen in Britain (the total British list of birds recorded here stands at more than 550). The bird has only put in three previous appearances – twice in 1977, when individuals were seen on Fair Isle, between Orkney and Shetland, and at Hornsea in east Yorkshire, and most recently in October 1995 when a bird was seen at Seaforth, Liverpool. So, for a determined lister it is worth a long journey to see it. "If it's not a lifetime experience, it's certainly a once-in-two-decades moment," Mr Unwin said.
He added: "It's a little bird that would look quite drab, were it not for the top of its head being coloured in such a way that implies it's a Newcastle United fan. But there are mind-blowing aspects to its appearance here. It's 17 cms long and weighs 20 grams, and to reach this point it has performed a mighty odyssey."
The sparrows nest in western North America – from Alaska to southern California, New Mexico and Arizona. The bird at Cley is probably from Canada and went off course while migrating to spend the winter in the southern USA or Central America.
"I would rate it nine out of 10 for its rarity here," said Peter Simpson, from Swaffham, Norfolk, who runs the website www.blueskybirds.co.uk, and has made his own pilgrimage to Cley.
"It's very hard to know how long it will stay. It could be there for weeks because it has found food and shelter and is happy in the company of a little flock of finches, or it could go any time."
Unlike European sparrows which are linked to the weaver birds of Africa, American seed-eaters given that name are closer to buntings.