Dartford Warbler Curruca undata


Justification of Red List Category
This species is declining at a moderately rapid rate, qualifying the species as Near Threatened. Declines in the core population in Spain are largely responsible for overall declines however other populations have also reported declines, including in France where the population is declining moderately rapidly. The drivers of the decline are not entirely clear but include habitat degradation and modification. Should the population be found to be declining more rapidly, the species would warrant uplisting to a higher threat category.

Population justification
In Europe (which covers c.85% of the breeding range), the breeding population is estimated to be 629,000-1,454,000 breeding pairs, based on 491,500-875,000 pairs in Spain, a new estimate of 25,000-50,000 pairs in France (Issa and Muller 2015), 100,000-500,000 pairs in Portugal, 10,000-30,000 pairs in Italy, c.20-30 pairs in Andorra and 2,900-3,600 pairs in the United Kingdom (BirdLife International 2015). This equates to approximately 1,255,000-2,910,000 mature individuals and 1,880,000-4,365,000 individuals.

Trend justification
Data from the Spanish common bird monitoring scheme (SACRE) suggest that the species may have declined by an average of 4.6% (95% CI: 6.2-3.1) per year during 1998-2011 (V. Escandell in litt. 2012), with declines occurring in all regions (and hence not simply attributable to a northwards shift in the species's range, as predicted under climate change scenarios). The European Red List of Birds estimated the population to be decreasing at a rate approaching 30% in 12.3 years or three generations (BirdLife International 2015). The population trend for the species produced by the Pan-European Common Bird Monitoring Scheme suggests that it declined by 32% over the period 1980-2012 and by 24% over the period 2003-2012 (EBCC 2016). Whilst populations in Portugal and the United Kingdom are increasing, declines have been reported for both France and Italy. The overall population trend is estimated to be decreasing at a rate of 20-29% over three generations.

Distribution and population

This species is restricted to southern and western Europe and north-west Africa, where it is patchily distributed but locally common to very common in Spain (including Balearic Islands), Portugal, Andorra, Morocco. Algeria, Tunisia, France (including Corsica), United Kingdom and Italy (including Sardinia) (del Hoyo et al. 2006). The European breeding population constitutes c.85% of the global population. The species's stronghold is located in Spain with an estimated 491,500-875,000 pairs in the period 2004-2006 (BirdLife International 2015). However the population here decreased by 4.6% per year between 1998 and 2011 (V. Escandell in litt. 2012). Portugal holds the next largest population with an estimated 100,000-500,000 pairs (BirdLife International 2015), followed by France (25,000-50,000 pairs) (Issa and Muller 2015). The population has undergone a strong increase in Portugal (A. Meirinho in litt. 2016) (100-300% increase for the period 2004-2011 according to the European Red List of Birds [BirdLife International 2015]) possibly owing to the availability of recently burnt areas (S. Herrando in litt. 2016). The population in France declined by at least 50% between 2001 and 2014 (E. Green in litt. 2016). In Italy (10,000-30,000 pairs) the population is declining although it is unclear to what extent (Monitoraggio Italiano Ornitologico and Lega Italiana Protezione Uccelli in litt. 2016). The population trend is unknown in Andorra (20-30 pairs). In the U.K. it has recently increased rapidly and extended its range northwards, reaching a total of 3,214 territories in 2006 (Wotton et al. 2009). The European population underwent a large decline during 1970-1990 (Tucker and Heath 1994) and further declined over the period 1980-2012 (32% decline) and in 2003-2012 (24% decline) (EBCC 2016).


It favours dense, homogeneous scrub, garrigue and low maquis c.0.5-1.5 m in height and dominated by species such as Ulex, Erica, CallunaRosmarinus, Genista, Cistus and Quercus coccifera (del Hoyo et al. 2006, Chiatante 2014, S. Wotton in litt. 2016). It is largely sedentary but undertakes some short-distance dispersive movements and some European birds spend the non-breeding season in north-west Africa (del Hoyo et al. 2006). It is primarily a lowland species in the north of its range but occurs to 1,800-2,000 m in the Pyrenees and north-west Africa (del Hoyo et al. 2006).


Reasons for the recent Spanish decline are still unclear. It is vulnerable to severe winters, particularly in the northern part of its range (del Hoyo et al. 2006). Cold spells in December 2001 and the winter of 2004-2005 and 2008-2009 caused high mortality in Spain (J. J. R. Encalado in litt. 2007) and France respectively (Jiguet and Williamson 2013, A. Regos in litt. 2016) , while the U.K. population was reduced to 11 pairs after the severe winter of 1962-1963 (del Hoyo et al. 2006) and again crashed in 2008 and 2010 following two cold winters (S. Wotton in litt. 2016). Research shows that the species is able to recover following population crashes brought about by freezing conditions, however this recovery is much stronger on heathland than in neighbouring early-growth forest (Jiguet and Williamson 2013). Current and future climate change are expected to alter the species's distribution in the north of its range (Huntley et al. 2008, Bradbury et al. 2011, Barbet-Massin et al. 2012).

Increasing densities of cattle on the Spanish dehesa are causing severe habitat degradation through overgrazing (J. J. R. Encalado in litt. 2007), which may be affecting the species. Afforestation has decreased the amount of suitable habitat in parts of France and Iberia (Shirihai et al. 2001). The species is reliant on dense, low shrublands that are often created as a result of past fires. With the species peaking in abundance a short time after the initial fire (e.g. c.3-4 to 9 years post fire) when the vegetation is most suitable (Jacquet and Prodon 2009, Pons and Clavero 2010, S. Herrando in litt. 2016). Changes in the pattern and frequency of wildfires as a result of fire suppression policies and climate change may reduce the area of suitable habitat for the species in Europe (Regos et al. 2015, P. Pons in litt. 2016). Post-fire forest management can negatively affect the species through the removal of burnt trees as the species has been shown to favour a moderate coverage of logging remnants after fires (Herrando et al. 2009), however, a non-significant positive effect of salvage logging has been described for this species (Rost et al. 2013). Building log piles is known to benefit the species (Herrando et al. 2009, Rost et al. 2010). In the UK there is some evidence to show that the species is adversely affected by disturbance from people and dogs (S. Wotton in litt. 2016).

Conservation actions

Conservation Actions Underway
Bern Convention Appendix II. EU Birds Directive Annex I. CMS Appendix II. The species was uplisted to Endangered in France in 2016 (UICN France, MNHN, LPO, SEOF and ONCFS 2016). Population trends are monitored in parts of the species's range and it occurs in a number of protected areas. In the UK the species is reliant on ongoing heathland management and restoration (S. Wotton in litt. 2016).

Conservation Actions Proposed
Carry out specific research on drivers of declines, particularly the link with habitats. Research trends elsewhere within its range, particularly France and North Africa. Develop programmes which subsidise farming practices which promote healthy populations of the species. In fire-prone, abandoned Mediterranean landscapes, conservation plans must integrate fire management programmes in order to preserve sparsely forested and early-succession habitats for this species (Regos et al. 2015). Protect shrublands from afforestation, agricultural development and urbanisation and encourage shrub encroachment on abandoned land (P. Pons in litt. 2016). Use fire, grazing or mechanical methods to avoid tree encroachment on suitable habitats (P. Pons in litt. 2016).


Text account compilers
Derhé, M., Ashpole, J, Taylor, J., Symes, A., Ekstrom, J., Mahood, S., Butchart, S.

Green, E., Herrando, S., Kirchner, F., Iñigo, A., Lega Italiana Protezione Uccelli, Pons, P., Monitoraggio Italiano Ornitologico, Escandell, V., Meirinho, A., Wotton, S., Regos, A., Encalado, J.

Recommended citation
BirdLife International (2022) Species factsheet: Curruca undata. Downloaded from http://www.birdlife.org on 05/10/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 05/10/2022.