Edition:
Online-Ausg. [Frankfurt am Main Univ.-Bibliothek] [2007] Online-Ressource [Online-Ausg.]
Content:
The area of Swedish wet meadows has decreased drastically during the last century due to cultivation and abandonment. During the same time the meadow bird fauna have changed considerably. Here the population sizes and recent trends for 33 bird species commonly occurring on Swedish wet meadows are reviewed. 16 of the species have declining populations; 7 species have increasing populations, while 10 have more or less stable populations. However, several of the species also occur in other habitats, and population changes in meadow habitats have probably been more extensive than reflected by the overall data. Generally, management dependent species, such as waders, have declined strongly, while passerines connected to unmanaged habitats have had stable or increasing populations. Since the 1980s conservation of wet meadow birds have been prioritized in conservation and the area of managed wet meadows have increased. Available data suggests that some species (Lapwing, Yellow Wagtail, Curlew and Redshank) have increased at least in some restored areas. However, no general increase in bird numbers was found for all species after restoration. We present evidence for four not mutually exclusive hypotheses explaining this result: (1) An increase in population size due to restoration measures is more likely if the target species is still present in the area. (2) Restoration measures fail to increase bird numbers if landscape composition and site characteristics do not meet the habitat requirements of the target species. (3) Since there are large differences between mowing and grazing and furthermore grazing intensity on the structure and composition of grasslands, target species might not benefit from restoration measures in the presence of unfavourable grassland management. (4) The lack of effectiveness of restoration measures on target species might be caused by insufficient water levels resulting from former regulations of rivers and lakes. It is recommended that evaluations of effects of restoration measures and different management regimes should be encouraged since high quality data for such evaluations are still scarce.
Note:
Online-Ausg.:
In:
Osnabrücker naturwissenschaftliche Mitteilungen, Osnabrück : [Naturwissenschaftlicher Verein Osnabrück], [1972]-, Band 32 (2006), Seite 99-106
In:
volume:32
In:
year:2006
In:
pages:99-106
Language:
German
URN:
urn:nbn:de:hebis:30-1153998
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