Grassland birds

Een rijk geïllustreerd boek, geschreven door zeven deskundigen op het gebied van landbouw en vogels en samengesteld door het Centrum voor Landbouw en Milieu (CLM), dat het vogelleven op landbouwgrond wereldomvattend in beeld brengt, is per 1 april 2010 verschenen. Het boek besteedt aandacht aan de vele bedreigingen waaraan vogels blootstaan. In de bijlage de lijst van vogels die in het boek staan.

Adult Lapwing Vanellus vanellus and chicks and adult Redshank Tringa totanus fed on a wide range of soil, surface-active and aquatic invertebrates on coastal grazing marsh throughout the breeding season. Adult Redshank also fed on estuarine invertebrates. The proportion of aquatic invertebrates in the diet of both species increased as the breeding season progressed, while that of soil invertebrates decreased.

There has been a massive 95% decline in the UK Tree Sparrow Passer montanus population between 1974 and 1999. The nestling diet of Tree Sparrows is largely composed of invertebrates. It is possible that due to agricultural intensification in the late 20th century and increased use and effectiveness of insecticides there has been a decline in invertebrate prey, rendering large areas of farmland as suboptimal breeding habitat for Tree Sparrows.

Starling Sturnus vulgaris populations have declined throughout Europe over the last two decades. The Starling is commonest in urban and farmland habitats, though density in the latter is much lower. Soil and ground-dwelling invertebrates, particularly leatherjackets (tipulid larvae) and earthworms, are the main prey of Starlings. The use of insecticides on grassland is targeted partly at tipulids, which may have reduced foraging opportunities for Starlings.

We compared bird communities of paired extensively and intensively grazed cattle pastures in three different regions of the Hungarian Great Plain. The extensive field and intensive field in a pair had the same soil type and groundwater level and were situated in similarly structured landscapes. Cattle density was about 0.5 cows/ha on extensive and greater than 1 cow/ha on intensive fields. None of the fields were fertilised, cut or re-seeded. We found significant effects of grazing intensity on the abundance of grassland birds, which were more abundant on the extensive sites, whereas no effects were found on non-grassland birds. The three commonest grassland species (Skylark Alauda arvensis, Yellow Wagtail Motacilla flava and Corn Bunting Miliaria calandra) were more abundant on the extensive fields in all regions.

In recent decades, the West European population of Black-tailed Godwits Limosa limosa (located mainly in the Netherlands) has declined at a quite alarming rate (5% per annum primarily due to declining productivity from 0.7 fledged young/pair in the 1980s to 0.2 fledged young/pair now) while the Icelandic population has undergone a rapid increase in population size (with a productivity likely to be 0.5-0.8 chicks/pair). The breeding habitats in the Netherlands, Germany, Belgium and Denmark are intensively farmed grasslands with high ground water levels in open landscapes, while in Iceland the breeding habitats are lowland marshes and dwarf-birch bogs. Godwits preferentially choose areas with high groundwater levels as breeding sites.

In einem interdisziplinären Forschungsvorhaben der Universität Kiel wurde untersucht, wie sich die Umstellung eines Landwirtschaftbetriebes auf ökologischen Anbau auf die Entwicklung der Brutvögelbestände auswirkt. Die auf Hof Ritzerau in Schleswig-Holstein ermittelten Ergebnisse deuten darauf hin, dass diese Umstellung vor allem die Siedlungsdichte der Feldlerche Alauda arvensis fördert.

Die Bestände von Neun­töter Lanius collurio und Feld­lerche Alauda arvensis nehmen deutsch­land­weit ab. Dies ist auch im Sauer­land fest­zu­stellen, wie die Orni­tho­lo­gi­sche Arbeits­ge­mein­schaft des "Ver­eins für Natur-und Vogel­schutz im HSK" (VNV) mitteilt. Die ehren­amt­li­chen Vogel­kundler nehmen alljähr­lich mehr als 50 Vogel­arten HSK-weit unter die Lupe, und stellten ihr Ergebnis beim Jahres­treffen im Kloster Bredelar vor. Knapp 25 Orni­tho­logen disku­tierten dort die Ergeb­nisse ihrer Bestands­auf­nahmen der Brut­saison 2008. Zu den Vögeln, die in der Agrarlandschaft leben, gab es schlechte Nachrichten. War die Feldlerche vor wenigen Jahrzehnten überall in der Feldflur zu hören, gingen die Bestände seitdem drastisch zurück. Auf vielen Acker- und Wiesenflächen des mittleren Sauerlandes, beispielsweise im Stadtgebiet Meschede, ist sie bereits ausgestorben.