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Marsh Grassbird Locustella pryeri
BirdLife is updating this factsheet for the 2016 Red List
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This species has a moderately small population, which is divided into a number of isolated sub-populations, and is likely to be declining as a result of wetland destruction in its breeding and wintering grounds, however recent surveys suggest that the population at Poyang Lake, China, could exceed 5,000 pairs (giving a global population exceeding 10,000 individuals), and the species has consequently been downlisted to Near Threatened.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Taxonomic note
Formerly placed in the genus Megalurus. Use of the genus Locustella follows Drovetski et al. (2004).

Megalurus pryeri BirdLife International (2004), Megalurus pryeri Sibley and Monroe (1990, 1993), Megalurus pryeri Collar et al. (1994), Megalurus pryeri BirdLife International (2000), Megalurus pryeri Collar and Andrew (1988)

14 cm. Medium-sized warbler. Light brownish-buff upperparts with black streaking except on rump and forehead. Indistinct pale supercilium. Buffy-brown tail feathers with dark shafts. Pale buff underparts becoming darker on flanks. Bright buff undertail-coverts.

Distribution and population
Locustella pryeri is known to breed at six localities on Honshu, in the prefectures of Aomori, Akita, Ibaraki and Chiba, Japan; in Jiangxi, Jiangsu and probably in Heilongjiang and Liaoning, China, and at Lake Khanka, Russia. Surveys in 2007 at Poyang Lake, Jiangxi, China indicated the presence of a potentially large population, estimated to be up to 5,000 pairs, 1,500 of which are within Nanjishan National Nature Reserve (He Fen-qi in litt. 2007, X. Huang in litt. 2007), and it has recently been found breeding on the Yangtze estuary (Jiangsu province) (S. Chan in litt. 2009) and in the Shanghai area (H. F. Cheung in litt. 2008). In 2001 it was breeding in Japan at Lower Iwaki-gawa (c.37-142 breeding males), Hotokenuma (35-448 breeding males), lower reach of Tonegawa (69-375 breeding males), Byoubusan area (nine singing males) and Ukishima (68-30 individuals in 1998) (Ueda 2003, K. Kato in litt. 2006). Its population at Ogata-sogen (58-122 breeding males in the late 1970s) has declined and recently disappeared (K. Kato in litt. 2006). It winters in Honshu and the Shikoku Islands, Japan and the Yangtze basin, China. There are a few records from eastern Mongolia and South Korea and it almost certainly occurs in North Korea. The population in Japan is estimated to be c.2,500 birds (Ueda 2003, K. Kato in litt. 2006).

Population justification
Survey work in Nanjishan National Nature Reserve has estimated a population of c.1,500 pairs in the reserve and at least 5,000 pairs around the lake as a whole (X. Huang et al. in litt. 2007), giving a global population exceeding 10,000 individuals but likely below 15,000. This roughly equates to 6,700-10,000 mature individuals. National population estimates include: < c.10,000 breeding pairs in China; c.100-10,000 breeding pairs in Japan and < c.100,000 breeding pairs and < c.1,000 individuals on migration in Russia.

Trend justification
The population is suspected to be declining as a result of habitat degradation and conversion in both breeding and wintering areas.

Breeding birds prefer dense, mid-height reeds and grasses in shallow water for nesting, with some taller plants for singing posts. It is very sensitive to habitat structure and does not tolerate vegetation that is too short or too tall. Wintering birds favour reedbeds. It is generally very reluctant to fly.

The main threat is the loss and degradation of marshes in its breeding and wintering grounds. Potential breeding sites at Lake Khanka are being converted to agriculture. Wetlands along Nen Jiang river, China, are threatened by oilfield development, reed harvesting for pulp, and alteration of water-levels through irrigation. In the Yangtze basin, wetlands are being destroyed and degraded. In Japan, many breeding sites are in abandoned rice-fields which would be lost if they were brought back into agricultural production. The key breeding site in Japan, Hotoke-numa, is threatened with conversion to pasture. Pollution and hunting are potential threats in China.

Conservation Actions Underway
CMS Appendix II. It is legally protected in reserves in Japan, where breeding sites at Hachiro-gata and Ogata-sogen are protected, and Hotoke-numa was designated as a RAMSAR Site in 2005 (K. Kato in litt. 2006). It has been recorded from protected areas at Lake Khanka (Russia), and Zhalong, Shuangtai Hekou, Poyang Hu and Dong Dongting Hu (China). A large population occurs within the Nanjishan National Nature Reserve (Jiangxi province, China). Conservation Actions Proposed
Survey potential breeding grounds in Russia, China and North Korea. Survey potential wintering grounds to improve understanding of winter range and habitat requirements. Develop habitat management plans in order to maintain suitable breeding habitat at key sites. Maintain and suitably manage known breeding sites. Ensure legal protection of all important sites. Ensure the legal protection of this species in all range countries.

BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.

Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

Ueda, K. 2003. Recent status of the Japanese Marsh Warbler. Strix 21: 1-3.

Further web sources of information
Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Bird, J., Butchart, S., Crosby, M., Gilroy, J., Khwaja, N., Peet, N., Symes, A.

Chan, S., Cheung, H., He, F., Huang, X., Kato, K.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Locustella pryeri. Downloaded from on 27/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 27/10/2016.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Marsh grassbird (Locustella pryeri) 0

Key facts
Current IUCN Red List category Near Threatened
Family Sylviidae (Old World warblers)
Species name author Seebohm, 1884
Population size 6700-10000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 132,000 km2
Country endemic? No
Links to further information
- Additional Information on this species