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 increasing, 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 2,020,000-3,190,000 pairs, which equates to 4,050,000-6,380,000 mature individuals (BirdLife International 2015). Europe forms c.35% of the global range, so a very preliminary estimate of the global population size is 11,570,000-18,230,000 mature individuals, although further validation of this estimate is needed.
The population is suspected to be increasing due to a northward range expansion in the west of its range. In Europe, trends between 1989 and 2013 show that populations have undergone a moderate increase (EBCC 2015).
This species favours swampy lowland areas with thick cover of reeds and sparse bushes (rarely in uniform reedbeds standing in water), willows (Salix), and brambles (Rubus) or blackthorn (Prunus spinosa). It is also found in overgrown ditches and streams with thick tangles of cover, areas of damp meadows, tall grass stands, hedgerows and overgrown orchards. In non-breeding areas, occurs in variably wet or dry scrub of plains, foothills, valley bottoms, bramble patches, overgrown orchards, and dense cover near water, marshes, swamps and reeds (Clement 2006). Breeding occurs mainly from mid-April to July/August. It lays two to four eggs. The nest is a large untidy cup of leaves, dry grass, plant fibres, feathers, animal hair and reed mace (Typha). It can be sited up to two metres from the ground in a thick tangle of vegetation, among the twigs or thin branches of a bush or stems of reeds or nettles (Urtica) (Clement 2006). It feeds mainly on insects but also takes other invertebrates. The species varies from sedentary to migratory in different parts of its range (Snow and Perrins 1998).
Particularly in the north-west of its range, it is susceptible to severe cold winters (Hagemeijer and Blair 1997, Robinson et al. 2007).
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
No conservation measures are currently needed for this species within Europe.
Text account compilers
Butchart, S., Ashpole, J, Ekstrom, J.
BirdLife International (2023) Species factsheet: Cettia cetti. Downloaded from http://datazone.birdlife.org/species/factsheet/cettis-warbler-cettia-cetti on 03/10/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 03/10/2023.