Marsh Warbler Acrocephalus palustris


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.

Population justification
In Europe, the breeding population is estimated to number 4,170,000-7,560,000 pairs, which equates to 8,330,000-15,200,000 mature individuals (BirdLife International 2015). Europe forms c. 95% of the global range, so a very preliminary estimate of the global population size is 8,750,000-16,000,000 mature individuals, although further validation of this estimate is needed.

Trend justification
In Europe the overall trend from 1980-2013 was stable (EBCC 2015).


This species favours rank, tufty and fairly tall herbage, especially nettles (Urtica), meadowsweet (Filipendula), brambles (Rubus fruticosus) and others, often in the vicinity of taller bushes or trees. It also occurs in corn fields and other agricultural land surrounded with a belt of low bushes or hedgerows as well as in wasteland with tall grass, herbs and small bushes, in tall herbaceous vegetation along ditches, in marsh vegetation at edges of swamps, in reeds on dry ground and even in gardens. In western and central Europe, breeding occurs from the second half of May to July. It lays three to six eggs in a nest which is a deep, cylindrical cup of leaves and stems of nettles, grass and other plants, lined with finer plant fibres, plant down and hair. The structure is supported on two to five plant stems, usually 30–70 cm high (Dyrcz 2006). It feeds mainly on insects and arachnids, with some snails and occasionally berries in late summer and autumn (Snow and Perrins 1998). The species is migratory, wintering in south-east Africa (Dyrcz 2006).


In the U.K., declines during the 1950s and 1960s may have been due to climate change and habitat loss as a result of activities such as bank tidying (Batten et al. 1989). The species is likely affected by climate change (Both et al. 2010).

Conservation actions

Conservation Actions Underway
CMS Appendix II. Bern Convention Appendix II. There are currently no known conservation measures for this species.

Conservation Actions Proposed
Sites should be protected and managed and in Britain the control of birdwatchers to reduce disturbance may be necessary (Batten et al. 1989).


Text account compilers
Ashpole, J, Ekstrom, J., Butchart, S., Symes, A.

Recommended citation
BirdLife International (2023) Species factsheet: Acrocephalus palustris. Downloaded from on 06/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from on 06/06/2023.