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 3,830,000-6,440,000 pairs, which equates to 7,650,000-12,900,000 mature individuals (BirdLife International 2015). Europe forms c.60% of the global range, so a very preliminary estimate of the global population size is 12,750,000-21,500,000 mature individuals, although further validation of this estimate is needed.
In Europe the overall trend from 1980-2013 was stable (EBCC 2015).
During the breeding season this species is found in a variety of low dense vegetation, often near water or in moist depressions, including shore vegetation around freshwater pools, along rivers and canals, and lowland swamps and marshes with reed and bush thickets. It can also breed in dry situations offering suitable cover, such as neglected orchards, hedgerows, nettlebeds, dense scrub, crop fields. In western Europe egg-laying occurs mainly from the end of April, from early May in central Europe and from mid-May in Finland. Clutches are from four to seven eggs and are laid in a rather deep cup with a loosely woven outer structure of grass, plant stems and leaves, moss and sedges, often with spider webs and a thick inner layer of finer leaves and stems, lined with reed flowers, hair and plant down. It is generally placed low over marshy ground (rarely above water) among grasses and tall weeds or in low bush. The diet is mainly insects and their larvae but it also takes spiders (Araneae), harvestmen (Opiliones), small slugs and snails. The species is migratory, wintering in sub-Saharan Africa (Dyrcz 2006).
Declines in this species in Europe have been attributed to severe droughts in the west African wintering quarters (Hagemeijer and Blair 1997, Dyrcz 2006).
Conservation Actions Underway
CMS Appendix II. Bern Convention Appendix II. There are currently no known conservation measures for this species within Europe
Butchart, S., Ekstrom, J., Symes, A., Ashpole, J
BirdLife International (2023) Species factsheet: Acrocephalus schoenobaenus. Downloaded from http://datazone.birdlife.org/species/factsheet/sedge-warbler-acrocephalus-schoenobaenus on 29/09/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 29/09/2023.