On our afternoon walk we were accompanied by a pair of wheatear, slim and elegant, their white rumps making identification easy as they bobbed along in front of us.

This distinctive plumage gives the bird its Norfolk name, 'white rump', and the name wheatear has the same derivation, from the Anglo-Saxon 'whit', meaning white, and 'aers', meaning rump.

In his 1835 poem The British Months, Richard Mant wrote 'Fain would I see the Wheatear show On the dark sward his rump of snow Of spotless brightness.'

Another Norfolk name for the wheatear, 'chuck' (also 'chock'), refers its short, quickly repeated cry, resembling two pebbles struck together, while 'coney chuck' reflects its habit of frequenting rabbit warrens. Local names from outside the region include 'fallow-finch' and 'clodhopper', from the bird's practice of following the plough and hopping from clod to clod in search of grubs.

Our pair will have crossed the Mediterranean, heading north from tropical Africa for their breeding grounds in the UK. They normally arrive between the last week of March and mid-April, but the British Trust for Ornithology reports that this year's spring migration has been intermittent. Weather fronts in the channel have blocked the birds' passage, and ten days ago only about a third of the expected numbers had been reported in the UK.

Fortunately, last week's spell of quiet weather saw them arriving in good quantities, and records are now as high as the average for this time of year.

There are two distinct races of wheatear that can be seen in the UK. While the more common form is a summer resident, the Greenland wheatear is a bird of passage, migrating to breeding grounds in Greenland and north-east Canada. It is larger and more brightly coloured than our native race, but Coward, in a guide to British birds published in 1920, suggests that it is the time of arrival on these shores that is most helpful in distinguishing between the two. He reports that the native birds arrive on the south coast in March, with successive waves continuing through April. By contrast, the Greenland wheatear passes through at the end of April and May. But Coward would have been confounded by this year's late migration, which goes against the trend, attributed to climate change, for migration to begin progressively earlier.