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Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	The birds of the lake district of Eggstatt - a balance after 40 years
Auteurs :	Bernd-Ulrich Rudolph, Auteur ; Guenther Nitsche, Auteur
Type de document :	Article
Dans :	Ornithologischer Anzeiger (47(2-3) DEC 2008)
Article en page(s) :	148-185
Résumé :	This study takes stock of changes to the birds in the lake district of Eggstatt (Upper Bavaria, 50 km(2)) between the periods 1959-1968 and 1997-2008. Causes of the changes are discussed against the background of a changing landscape and protection efforts. The study area contains more than 20 natural lakes, some fens and peat bogs and a large (1008 ha) nature reserve. Its central parts are designated as a Special Protection Area (nr. DE8040-471). Between 1959 and 1968, 93 species regularly bred and 12 species irregularly; between 1997 and 2008, there were 92 regular and 13 irregular breeding species. Between the two periods, eleven species were lost and 18 declined, whereas 12 species moved in or became established as regular breeders and 13 others increased. Waterfowl, meadow and farmland species, and birds of settlements and forests variously show both decreases and increases. However, mainly specialised species disappeared or declined (e. g. Little Bittern, Black Grouse, Redshank, Snipe, Spotted Crake, Hoopoe, Great Grey Shrike) indicating that vast and intact habitats disappeared, e. g. following changes to the water balance of fens and peat bogs. The increase or immigration of some species of wet meadows, reeds and marshland (Marsh, Sedge and Grasshopper Warbler), which benefit from vegetational succession following the abandonment of formerly used fen habitats, may be regarded as a positive side to these negative developments. The arrival of some marshland species as Stonechat and Bluethroat occurred in a wider context of expansion. This is also the case for some other species, which have been spreading more widely in Southern Germany (e. g. Greylag and Canada Goose, Red-crested Pochard, Tufted Duck). Conversely, such typical farmland birds as Partridge and Skylark have decreased or disappeared from many other parts of Central Europe. Positive developments in forest bird communities (e. g. jackdaw, Nuthatch, Tree Pipit) are attributed to increased age of trees and to changes in forest structure because of increasing harvest of spruce stands destroyed by beetles in the last ten years. Some very recent increases in meadow breeding birds and fen species result from habitat management. However, these protection efforts can only partly compensate the large losses of moor and fen species.Regarding guests and migrants, Cormorant, Great Egret und Mediterranean Gull are new species and numbers of Grey Heron strongly increased. However, the importance of the lakes as resting or moulting places for waterfowl is relatively low. The nutrient rich and relatively shallow lakes in the northern part of the study area are much more important breeding places for most species (0,6-2,5 BP/100 m bank line) than the deeper and oligo-mesotrophic lakes in the nature reserve (0,2-0,8 BP/100 m bank line).

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