Tuesday, 2 May 2006

Continued rise of the Collared Dove

Perhaps unfairly, I have always considered the collared dove to be something of a stupid bird. This view was reinforced the other day when I spotted one incubating eggs in a nest, precariously balanced on narrow branches above the middle of the River Little Ouse. Should the wind get up, I thought, then the nest would slip between the branches and into the river. Sure enough, two days later the nest was gone. Despite the fact that collared doves build nests in some pretty silly places, and that such nests are usually just a pathetically small platform of twigs, the species has done amazingly well over the last fifty years.

The collared dove was first recorded nesting in Britain in 1954, when two young were reared from a nest in a small garden at Cromer. Since then, the species has spread across the rest of Britain and it is now one of our most familiar birds. The colonisation of Britain was part of a wider expansion in breeding range that took place across Europe. Up until the 1930s, the species was largely restricted, within Europe, to Turkey and the Balkans. Over the following 20 years, there was a dramatic range expansion to the northwest, extending the known range by more than 1,600 km. Most of the initial spread within Britain was linked to villages and suburbs, suggesting that the provision of supplementary food at garden feeding stations and the availability of spilt grain around farmyards was helping the species. Breeding behaviour also seems to have played a part, since collared doves are known to have a large number of breeding attempts each year. One well-watched pair had seven attempts in one year, though most of these failed. Although nesting has been recorded in all months of the year, the main breeding season extends from mid-February to mid-October. The birds seem able to start a new breeding attempt before the previous one has finished, with females using breaks from incubation to attend to young from the previous attempt. Such persistence has clearly paid off, helped by a lack of competition from other species and easy access to food throughout the year.

The question of what triggered the initial expansion in range has been much debated. Some authors suggest that it was due to a genetic mutation; others put it down to climate change or link it to agricultural intensification. To be honest, we don’t really know but the tendency for young birds to disperse some distance away from where they were born, coupled with the capacity to produce large numbers of young has established this species in our avifauna. Perhaps the collared dove is not as stupid as it first appears.

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