On the origin of the dove species

Dove-grey can sound a sad sort of colour, but it gives a pale and polished beauty to the birds that flash down through our trees in early morning.

They land with a flourish of white tail-feathers on stones of a darker grey than themselves - the limestone chippings of the "street" - and forage there at an elegant pace for weed seeds and beetles. I think of some ancestral columbiform gene, alert to any echo of parched village paths in the shade of acacia groves.

Rural India was the heartland of the collared dove before its astonishing expansion to the west. Up to about 1930, it had reached no further than the Balkans, possibly introduced there by man, but in the next 40 years it colonised about 2.5 million square kilometres of western Europe. It first bred in Britain in 1955 and in Ireland a few years later; it was noticed first in Galway in 1959. By the mid-1960s the doves were widespread, puzzling people with a fluting, forceful call that has the carrying power of the cuckoo; you-fool-you! is not a bad rendering.

What triggered their astonishing expansion is still not fully understood. The birds have a long breeding season - February to October in these islands - and while predators such as magpies and hooded crows are quick to raid their twiggy nests in trees early in the spring, the doves' response is simply to try again; some pairs studied in Britain reared up to five broods in one season.

By the end of the 1900s there were perhaps 30,000 collared dove territories in Ireland. The latest breeding atlas shows them concentrated in the lowlands of the north-east and on the richer farming areas of the Republic. In the countryside, they like clustered farmsteads with shelter-belt conifers to nest in, a supply of spilled grain, a bit of bare ground and plenty of overhead wires on which to rest or roost. But suburban and small-town gardens with conifers and bird-tables will often fit the bill just as well.

Did Ireland have no wild doves of her own? Indeed - five or six if we add in the pigeons (they are all the Columbidae family).

The slatey-blue rock dove, ancestor of the feral, multi-hued pigeon of city streets, is the really wild species, if shyness is the measure. In its pure form it now lives only on the more remote cliffs and islands of our oceanic coasts, nesting in caves and crevices and feeding in coastal fields.

I have watched small flocks in winter in north Mayo, flying with fierce speed above the swells of Inishkea. Their wing markings are distinctive - black bars above and silvery-white below - but it is the dashing, steep-angled beat of the wings and the urgency of flight that look so much at home in an untamed landscape.

By contrast, the stock dove is a blow-in, if not quite as recently as the collared dove. Its northwards expansion in Britain took place in the late 1800s, reaching Co Down by 1877 and spreading out rapidly thereafter, especially to the farmland of Leinster and the hinterland of Cork city. It's a rather delicate-looking blue-grey pigeon with a black band on its tail, and while it uses the same sort of countryside as the woodpigeon - trees and fields - it is smaller and stockier and has no white on it anywhere.

The small, slender, turtle dove is a scarce summer visitor but unmistakeable, both for its purring song and rich appearance (wings a lovely light chestnut flecked with black). Seeing it is mostly a rare delight for people walking the coasts of the east and south in spring and autumn, when the dove is on passage to and from the Continent.

Which leaves us with the ubiquitous pigeons of town and country, both treated as invisible by the average bird-watcher. I once lived beneath nesting woodpigeons in Dublin suburbia (their conifers towered over the house) and had to adapt to their remorseless variations on coo and sudden, heart-stopping clattering into flight. Now I live just beyond the last hill from their islandwide occupation; 970,000 pairs at the most recent estimate, despite the winter fusillades from Italians in tweeds.

Woodpigeons had their expansion in the early-19th century. John Watters, in his 1853 bird book, found 27 occupied nests in a demesne just outside Dublin. To him, the pigeon was the "woodquest" or "ringdove" and the male's "amatory notes" an obvious source of pleasure.

At around the same time Charles Darwin belonged to two London pigeon fanciers' clubs. Astonished by breeds as different as tumblers, fantails, pouters and turbits, he reached many of the conclusions in the first chapter of The Origin of Species. After centuries of domestication, initially for food, the breeds had changed not only appearance but the numbers of bones and feathers. "Great as are the differences," wrote Darwin, "I am fully convinced that all are descended from the rock pigeon."