This 5km-long stretch of windswept terrain is famous for a breed of sheep which subsist almost entirely on seaweed. In the days when kelp was harvested, a dry-stone wall around the island’s perimeter kept the sheep in from the shoreline. Nowadays it keeps them out; the animals feed at low tide and ruminate when the seaweed is covered. Bones of the legendary great auk, a species which became extinct in 1844, were found at a Neolithic site on North Ronaldsay. A bird observatory, the Scottish equivalent of the one at Cape Clear, was set up there in 1987.
There’s an airstrip and a ferry service from Orkney but few outsiders visit the island. It was a different story, however, on the May bank holiday weekend. The observatory’s chief assistant warden, Simon Davies, had spotted a streaky-brown bird, slightly larger than a starling. The visitor was identified as an American red-winged blackbird, a species not recorded previously in Europe. Media reports sent twitchers into a tizzy; enthusiasts from all over the UK and elsewhere headed for North Ronaldsay. Some even chartered planes to get there.
Despite its name, the species is not related to the European blackbird or the redwing. They are thrushes. The five ‘blackbird’ species of north America belong to the ‘icterid’ family, whose name derives from the Greek meaning ‘jaundiced’; New World orioles, the most glamorous members of the tribe, have yellow plumages. Male red-winged blackbirds sport conspicuous red ‘shoulders’ and have yellow bars on their wings.
The North Ronaldsay visitor, however, is not the brightest star in the avian firmament; photos on the web show what looks like an overgrown house sparrow with a longish pointed bill. Only its mother, or a starry-eyed twitcher, could love so plain a bird! Some hen American blackbirds have faint red markings but this female lacks them.
There are two candidate explanations as to how the visitor crossed the Atlantic. Some blackbirds from the northern US and Canada spend the winter in southern states and Mexico. Did this one get lost while returning northwards to nest, strong winds sweeping it eastwards? Or did it hitch a ride on a ship?
The red-winged blackbird may be North America’s commonest land-bird species, its population even exceeding 250m occasionally with flocks of over 1m recorded. With so many birds moving about and migrating over long distances, it seems extraordinary that none reached Europe until now. American robins, New World warblers, and even monarch butterflies, regularly visit our shores. Why don’t blackbirds do so?
Seeing mixed flocks of blackbirds feeding on insects and seeds in the American countryside, reminded me of the roving teenage gangs of young starlings you encounter in Ireland in late summer. The similarities in behaviour are striking. These birds, like ours, are intelligent gregarious and well able to exploit any opportunities we inadvertently offer them.
In the late 19th century, the American Acclimatisation Society introduced to the US every bird species Shakespeare mentioned. “I’ll have a starling shall be taught to speak nothing but ‘Mortimer’, and give it him, to keep his anger still in motion,” declares Hotspur in Henry IV.
So a hundred starlings were released in Central Park, New York, in 1890 and 1891.
Accused of damaging property, spreading invasive plants and threatening air safety, their descendants have become a major pest, costing the US and Canada, it is alleged, up to €113bn annually. Starlings and American blackbirds, it seems, have similar habitat requirements. Does this mean that American blackbirds would fare equally well if they set up shop on this side of the Atlantic. If not just a single bird, but an entire flock, were to arrive and settle here, would the species conquer Europe?