The Dartford warbler (Curruca undata) is a Sylviid warbler from the warmer parts of western Europe and northwestern Africa. It is a small warbler with a long thin tail and a thin pointed bill. The adult male has grey-brown upperparts and is dull reddish-brown below except for the centre of the belly which has a dirty white patch. It has light speckles on the throat and a red eye-ring. The sexes are similar but the adult female is usually less grey above and paler below.

Its breeding range lies west of a line from southern England to the heel of Italy (southern Apulia). The Dartford warbler is usually resident all year in its breeding range, but there is some limited migration.

Taxonomy and systematics

The Dartford warbler was first described in 1776 by the Welsh naturalist, Thomas Pennant. He introduced the English name and based his description on two specimens that had been obtained by the ornithologist John Latham from Bexley Heath, near Dartford in Kent. In 1783 Latham included the warbler in his A General Synopsis of Birds but did not coin the binomial name, Sylvia dartfordiensis, until the supplement to his work was published in 1787. However, in 1783, before the publication of Latham's supplement, the Dutch naturalist Pieter Boddaert introduced the name, Motacilla undata, based on a coloured plate of "Le Pitte-chou, de Provence" in Edmé-Louis Daubenton's Planches enluminées d'histoire naturelle. The specific epithet undata is from Medieval Latin undatus meaning "with wavy markings". The type locality is Provence in France.

This species probably forms a superspecies with Tristram's warbler and this in turn seems close to Marmora's warbler and the Balearic warbler. Altogether, this group of typical warblers bears a resemblance to the wrentit, the only species of Sylviidae from the Americas. However, the wrentit is less closely related to the genus Sylvia than to the parrotbills. Its visual similarity to the Dartford warbler group is an example of convergent evolution.

Three subspecies are recognised:

  • C. u. dartfordiensis (Latham, 1787) – south England and north-west France
  • C. u. undata (Boddaert, 1783) – Iberian Peninsula and south France It is formed mainly of grasses and is lined with a layer of finer material that can include thin roots and feathers. The eggs are laid from early April in southern France and Spain, and from mid-April in southern England. The eggs are incubated for 12–14 days mainly by the female. The chicks are fed arthropods by both parents. The nestlings fledge 10–14 days after hatching and are then fed by their parents for a further two weeks.

However, this species can recover well in good quality habitat with favourable temperatures and rainfall, thanks to repeated nesting and a high survival rate for the young. Indeed, they recovered in some areas of the UK, but numbers are once again on the decline in other regions of their natural range.

The range of the Dartford warbler is restricted to western and southern Europe. The total population in 2012 was estimated at 1.1–2.5 million breeding pairs. The largest numbers occur in Spain where there were believed to be 983,000–1,750,000 pairs. For reasons that probably include loss of suitable habitat, the Spanish population appears to be declining. The species is therefore classed by the International Union for Conservation of Nature as being Near Threatened.

References

Sources

  • BirdLife International (BLI) (2008): 2008 IUCN Redlist status changes. Retrieved 23 May 2008
  • <!--https://books.google.co.uk/books?id=gyTZKwGPvUMC -->
  • Ageing and sexing (PDF; 3.1 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze
  • Photos and videos from the Internet Bird Collection
  • Vocalisations on Xeno-canto