Feeling blue, is this little relative of the robin Britain’s rarest bird?

CALL OF THE WILD: A pair of red-spotted bluethroats are known to have raised their young in the Cairngorms

CHRISTMAS dinner with all the trimmings had gone down a treat and the waft of gunpowder from pulled crackers filled the air with smoky cheeriness. The Queen had spoken. Tins of toffees were being eased open and a festive family quiz around the dining table sounded a jolly idea.

One question spurred a debate as heated as Brexit and as a confounding as a Sherlock Holmes mystery: What is Britain’s rarest bird? Some said the avocet, others the golden eagle. All eyes focused on me as resident Birdman to answer.

With nervy thoughts of the same puzzler popping up again this year as the old quiz game is retrieved from the attic, I thought best to seek advice to resolve the hoary chestnut. So I asked the British Trust for Ornithology’s resident expert Paul Stancliffe. His explanation was not so much a “starter for 10” but an academic treatise into the wonders of our rich and fascinating bird life. To begin, Paul explained, there are 619 potential candidates that appear on the official British List, the scientifically approved document that records every species to have occurred naturally from St Kilda to the Isles of Scilly.

While around 250 species either nest every summer, over winter or pass through as migrants, the bulk of the list is made up of vagrant species that arrive sporadically from all points of the compass, straggling from the wilds of Siberia to the doldrums of the South Atlantic.

Reports of their occurrence are adjudicated by the British Birds Rarities Committee, its annual report one of the highlights of the year for the nation’s army of twitchers. It is on the “B” list where likely contenders hover, birds so rare they have not been recorded on our shores since 1949. Some, such as the great auk and Eskimo curlew, are extinct, others last recorded when Victoria reigned: Pallas’s gull in 1859, greater spotted eagle (1860) and white-faced storm petrel (1897). Algeria’s red-necked nightjar – seen once in Northumberland in 1856 – remains the most elusive species and a candidate for our rarest bird.

LOOKING from a conservation angle, while the red-necked nightjar has the lowest global threat status, a species that turns up fleetingly off the south coast each autumn is a wing beat from extinction. The Balearic shearwater with fewer than 20,000 individuals is classified as Critically Endangered on the Red List of Threatened Species, a status on a par with tigers, gorillas and orangutans, the rarest of the rare.

Paul explained that rarity can also be assessed by virtue of the numbers of a species nesting on our shores and pointed me towards the latest report of the Rare Breeding Birds Panel. Among those tallied are some that were once widespread across the country such as the lesser spotted woodpecker, willow tit and cirl bunting, which have declined tremendously. Others, such as the white-tailed eagle and Montagu’s harrier, have the flimsiest talon-hold, with only a few laying eggs each spring.

Two species stand out by reason of their tenuous grip as nesters. Indeed, the little gull produced its first successful British clutch two years ago at a Scottish RSPB reserve. At the same time, a pair of “red-spotted” bluethroats were successfully raising young in the Cairngorms. Five breeding attempts throughout history have only seen a dearth of fledglings produced by this distant cousin of our beloved robin redbreast. Declaring the bluethroat, with its shimmering sapphire gorget, Britain’s rarest bird has a warming, festive feel and would certainly get a nod from any quizmaster.