Plenty love for doves but not so much for 'rats with wings'

Scientists have been analysing the DNA of domestic pigeons and wild doves to study the extent of mixing between the breeds

Pictured: pigeons at Cork's Peace Park. Scientists have been comparing the DNA of pigeons and wild doves

The dove, international symbol of peace, represents the Holy Ghost in Christian iconography. Andrew Blechman in Pigeons: the Fascinating Saga of the World’s most Revered and Reviled Bird says that they have themselves been worshipped as fertility goddesses. Carrier pigeons served every superpower from ancient Egypt to modern times. News of the outcome at Waterloo in 1815 came courtesy of an avian courier. Pigeons which ran the gauntlet of enemy fire during ‘the Great War’, had Croix-de-Guerre-type medals awarded to them.

Nor do doves benefit only humans. Lowly ‘street’ pigeons are a steady source of food for large raptors, enabling peregrines, which came close to extinction here during the 1960s, to breed in our towns and cities.

Pigeon fouling outside the Office of the Attorney General

But not everyone loves pigeons. We call the ones we like ‘doves'. Those we despise we refer to as ‘pigeons’. ’These ‘rats with wings’ soil listed buildings with their corrosive droppings and can be a public nuisance. During the 1950s, the US Fish and Wildlife Service fed them cyanide-coated peanuts in Boston, inspiring Tom Lehrer's 'Poisoning Pigeons in the Park'. Apparently, the pianist hired for the studio recording fell off his stool on discovering the song’s theme and title.

Fossil remains suggest that the rock-dove was domesticated in the Middle East some 10,000 years ago. Bred to serve as postmen, racers, or to be eaten, many domestic varieties have emerged over the millennia. Escapees are no longer beholden to people; feral pigeons do their own thing.

The European wildcat’s genome has been contaminated through interbreeding with its household cousin, whose ancestors belonged to a North African variant. Likewise, the feral pigeon has introduced alien genes to the wild rock-dove population. Birdwatchers know this and regard white-rumped grey doves as virtual farmyard fowl, unworthy of inclusion on a watcher’s list.

Pigeons flying over and walking on a section of the Lough, Cork when it froze during the winter. Picture: Denis Minihane

This history raises an intriguing question. With feral domestic doves so ubiquitous, has the mixing of breeds rendered the ‘pure’ rock-dove strain extinct?

Researchers at Oxford University have been addressing this. Wild rock doves live along sea-cliffs, breeding in holes and on ledges in caves. Although feral domestic pigeons might visit such remote locations occasionally, interbreeding between the two varieties seems limited. Pigeon expert, Derek Goodwin, claimed that liaisons occur between feral and wild doves but they are rare.

Pigeons fly as Muslim pilgrims pray on top of the rocky hill known as the Mountain of Mercy, on the Plain of Arafat, during the annual hajj pilgrimage, near the holy city of Mecca, Saudi Arabia, Friday, July 8, 2022. Picture: AP Photo/Amr Nabil

William Smith, lead author of a paper just published, obtained feathers from rock-doves captured by bird ringers in the Hebrides Orkneys and Cape Clear, locations where encounters between wild and domestic ones were considered unlikely. DNA from the feathers was analysed and the extent of genetic contamination measured.

The result showed that both the Scottish and Irish doves showed ‘levels of introgressive hybridisation with feral pigeons, but to different extents’. There was significant variation between sites; ‘this analysis revealed negligible admixture in the Outer Hebrides, some in the Inner Hebrides & Arran Group, and higher level in all individuals in the Cape Clear and the Highlands & Orkney group’.

The research confirms that the ancestral form of the rock dove has been compromised. The species has a worldwide distribution, however. Perhaps the pure ancient form survives somewhere?