River Warbler Locustella fluviatilis


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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to 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 2,330,000-5,360,000 pairs, which equates to 4,650,000-10,700,000 mature individuals (BirdLife International 2015). Europe forms c.80% of the global range, so a very preliminary estimate of the global population size is 5,800,000-13,400,000 mature individuals, although further validation of this estimate is needed.

Trend justification
In Europe the overall trend from 1982-2013 was decreasing (EBCC 2015).


During the breeding season this species is found in dense low vegetation, grass thickets, nettles (Urtica) and tangled herbage in meadows, moist woodland, damp forest clearings and sedge marshes. It also uses riverbanks and abandoned cultivation. In the African non-breeding quarters the species uses dense green bush and scrub, rank herbage, tall grass and woodland undergrowth. Egg laying begins from end of May and continues to mid-July in east Europe. The nest is a loose cup of grass stems and leaves, lined with finer grasses and hair. It is built in thick vegetation or at the base of a bush, on or very close to the ground and commonly has an approach “run” or corridor. Clutches are typically four to six eggs. It feeds mainly on insects but also takes spiders (Araneae), small ticks (Acarina), millipedes (Diplopoda) and small molluscs. The species is a long-distance migrant, wintering in eastern and southern Africa (Pearson 2006).


There are not thought to be any current significant threats to this species.

Conservation actions

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

Conservation Actions Proposed

Research to identify causes of population declines and appropriate conservation measures.


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

Recommended citation
BirdLife International (2023) Species factsheet: Locustella fluviatilis. Downloaded from on 10/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from on 10/06/2023.