DIJK VAN AJ, HAAN B DE, MESSEMAKER R & VERBIJ P (2012) Breeding birds of the peat marshland of De Wieden in 2004 - 2011. LIMOSA 85 (4): 145-160.

In de northwest of the province of Overijssel one of the larger Dutch peat bog marshlands is situated. De Wieden (9260 ha) is part of the National Park Weerribben and Wieden, and a designated Natura 2000 site. The landscape consists of shallow lakes and canals, marshland, wet meadows and wet alder-birch forest. Each year in large parts reed is cut for commercial use. Farmland and villages are mainly found along the edges of the study area (Fig. 1). In 2004-2011 all breeding birds were censused in most of the area using the Dutch variant of the territory mapping method. 138 breeding species and a total of 34,300 breeding pairs were found (table 1, appendix 1). The most abundant species were Willow Warbler Phylloscopus trochilus (2100-4500 pairs), Eurasian Reed Warbler Acrocephalus scirpaceus (1800-3800), Sedge Warbler A. schoenobaenus (2700-3500) and Common Reed Bunting Emberiza schoeniclus (1500-3000).
      Marshland birds represent 51% of the avifauna. The colonial Black Tern Chlidonias niger, Eurasian Spoonbill Platalea leucorodia, Great Cormorant Phalocrocorax carbo, Grey Heron Ardea cinerea, Purple Heron A. purpurea and Western Great Egret Casmerodius albus are striking representatives in this group, alongside Bluethroat Luscinia svecica, Common Grasshopper Warbler Locustella naevia, Common Reed Bunting, Eurasian Coot Fulica atra, Eurasian Reed Warbler, Great Crested Grebe Podiceps cristatus, Greylag Goose Anser anser, Mallard Anas platyrhynchos, Savi's Warbler Locustella luscinioides and Sedge Warbler. Large open fields of mown reeds are favored by Common Snipe Gallinago gallinago, Eurasian Curlew Numenius arquata and Northern Lapwing Vanellus vanellus. In the newly grown reeds many Eurasian Reed Warblers settle, while remaining stands of uncut reed are favoured by Bluethroat, Eurasian Reed, Savi's and Sedge Warblers.
      Woodland birds (14,301 pairs of 54 species) account for 42% of the avifauna, while only 13% of De Wieden consist of forest. The relatively young alder-birch forests are predominantly inhabited by Willow Warbler, Common Chiffchaff Phylloscopus collybita, Eurasian Wren Troglodytes troglodytes, Garden Warbler Sylvia borin and Tree Pipit Anthus trivialis. Species of old forest like Short-toed Treecreeper Certhia brachydactyla, Eurasian Nuthatch Sitta europaea and Hawfinch Coccothraustes coccothraustes are scarce. Farmland represents 4% of De Wieden. Meadow Pipit Anthus pratensis and Northern Lapwing are the most abundant meadow birds alongside Black-tailed Godwit Limosa limosa, Common Redshank Tringa totanus and Northern Shoveler Anas clypeata. The number of breeding birds in villages and buildings is modest with 3% of the total bird population. Barn Swallow Hirundo rustica, House Sparrow Passer domesticus and White Wagtail Motacilla alba are by far the most numerous representatives.
      The proportion of the national population that breeds in De Wieden is strikingly large (10-20%) for Black Tern, Common Snipe, Purple Heron, Savi's Warbler and Sedge Warbler, making this one of their main breeding areas in The Netherlands. The area is also nationally important for Common Grasshopper Warbler, Eurasian Bittern, Eurasian Curlew, Gadwall, Garganey, Great Cormorant, Spotted Crake, Water Rail Rallus aquaticus and Western Great Egret..

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