Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
In Europe, the breeding population is estimated to number 4,460,000-7,760,000 pairs, which equates to 8,930,000-15,500,000 mature individuals (BirdLife International 2015). Europe forms approximately 25% of the global range, so a very preliminary estimate of the global population size is 35,720,000-62,000,000 mature individuals, although further validation of this estimate is needed. National population estimates include: c.100-10,000 breeding pairs and c.50-1,000 individuals on migration in China; < c.50 individuals on migration and < c.50 wintering individuals in Taiwan; < c.1,000 individuals on migration and < c.1,000 wintering individuals in Korea; < c.50 individuals on migration and < c.50 wintering individuals in Japan and c.100-10,000 breeding pairs and c.50-1,000 individuals on migration in Russia (Brazil 2009).
The European population is estimated to be stable (BirdLife International 2015). In the absence of evidence for any declines or substantial threats, the global population is tentatively assessed as being stable.
For breeding, this species appears to require copious low dense vegetation with patches of open ground. It breeds in ecotone habitats between forests and plain or open areas at the tree-line, including wooded tundra, mountain steppe, subalpine scrub, marshland with low woody cover, clumps of willow (Salix), alder (Alnus) and birch (Betula) on floodplains, riverbank thickets, reedy and shrub-dominated lakeshores, bushy sites near water. The breeding season lasts from late April to July in central Europe, from late May in Scandinavia, early April to June in Armenia, June to July in Ladakh, May to July in China and May/June to August in North America. The nest is a deep cup of leaves, small twigs, dry grass, rootlets, plant down and moss, which is occasionally lined with animal hair. It is placed among grass and scrub on wet ground and is commonly associated with topographic features such as a hummock, gulley, lip of a bank, or tussock. Clutches consist of four to seven eggs. The diet is principally invertebrates, particularly insects, but it does take some seeds and fruit in the autumn (Collar 2015). The species is mainly migratory, with west Palearctic populations wintering in patches across the Mediterranean Basin and the northern Afrotropics and eastern populations in the Indian subcontinent (Snow and Perrins 1998).
In Europe, Bluethroat experiences pronounced, but largely unexplained, population fluctuations (Hagemeijer and Blair 1997, Collar 2015). Some negative trends appear to be explained by natural succession in marshland, drainage and management practices such as reed-cutting, seedling removal and cattle grazing (Hagemeijer and Blair 1997), but recovery has taken place without the reversal of these circumstances. In Spain, during the 1990s Bluethroat may have suffered from degradation of habitat through grazing. In Austria, significant losses occurred during the 19th century due to drainage. Now, the species faces threats there due to the stabilization of lake levels and the subsequent loss of the reed-belt, as well as due to the occupation of secondary habitats on arable land and subsequent elevated nest predation (Collar 2015).
Conservation Actions Underway
CMS Appendix II. EU Birds Directive Annex I. There are currently no known conservation measures for this species within its European range.
Conservation Actions Proposed
In Bavaria, growing numbers may collapse unless succession is contained through habitat management (Collar 2015). This species would benefit from further research on the causes of population fluctuations.
Text account compilers
Butchart, S., Ekstrom, J., Hermes, C., Ashpole, J
BirdLife International (2020) Species factsheet: Cyanecula svecica. Downloaded from http://www.birdlife.org on 05/06/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 05/06/2020.