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.
A richly illustrated book written by seven experts in biology and agriculture and compiled by the Dutch Centre for Agriculture and the Environment (CLM) reviewing birdlife on farmland on a global scale has been released on 1 April 2010. The book identifies the threats facing farmland birds and explores the available opportunities for their protection. A bird list is enclosed.
A study identified two factors that may limit breeding productivity of the Reed Bunting Emberiza schoeniclus, which is in significant decline in England since the 1990s: ground vegetation providing concealment from nest predators and availability of invertebrate prey for chicks. The increased use of pesticides may have reduced invertebrate densities on most farmland.
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.
There has been a large population decline of the song thrush Turdus philomelos in Britain during the last three decades, which has reduced breeding densities on farmland by nearly 70% between 1968 and 1999. Survival of birds in their first year of life after fledging was shown to have a great impact on population changes. Changes in survival in the first winter are sufficient to have caused the song thrush population decline. Earthworms and other soil-dwelling invertebrates form a large component of the diet of song thrushes, particularly between December and May. Earthworms move deeper into the soil and/or become inactive during periods of cold weather and hence become less available as prey for song thrushes. Reduced availability of invertebrate food could explain reduced survival in the winter.
Farmland bird decline and pesticides
Author : Dr. Sue Armstrong Brown
Pesticides et déclin des oiseaux des milieux agricoles
60% des espèces d’oiseaux d’Europe vivent en milieu agricole. Les pesticides détruisent les invertébrés : insectes, scarabées, araignées (plus globalement : les arthropodes dont les insectes et les annélides NdT) une ressource alimentaire importante pour les poussins. Les herbicides font disparaître les graines des plantes sauvages – une ressource alimentaire particulièrement importante durant les mois d’hiver. Les herbicides réduisent aussi les populations d’invertébrés par élimination des plantes hôtes. Une corrélation temporelle frappante entre le début du déclin et l’usage des pesticides existe pour les moineaux friquets, les tourterelles des bois, le bouvreuil, la grive musicienne, le moineau domestique, le vanneau, le bruant des roseaux, l’alouette des champs, la linotte mélodieuse, les hirondelles, le merle et l’étourneau.
The Reed Bunting (Emberiza schoeniclus), the Skylark (Alauda arvensis), the Song Trush (Turdus philomelos), the Tree Sparrow (Passer montanus) and the Turtle Dove (Streptopelia turtur) have suffered a dramatic decline in numbers across Essex over recent years. The increased use of insecticide on Essex farmland would be expected to have a detrimental effect on the population of the Song Thrush, which is an invertebrate feeder, but a reduction in the number of insects, such as beetles, after insecticide spraying could also be an important factor in the decline of the Reed Bunting and the Skylark, which feeds its young exclusively on insects during the first weeks of life.
Het is vrijwel zeker dat de ortolaan (Emberiza hortulana) door het gebruik van pesticiden in de intensieve akkerbouw inmiddels uit Nederland en Vlaanderen is verdwenen. De precaire stand van de ortolaan in Zwitserland was aanleiding om in 2007 een onderzoek te starten naar de habitat- en voedselkeus van broedvogels met jongen, maar snel werd duidelijk dat de werkelijkheid het onderzoek had ingehaald. Er werd niet meer gebroed. Er werd een poging gedaan het foerageergedrag van de laatste Zwitserse ortolanen vast te leggen. Bespoten mais werd het vaakst gebruikt as foerageergebied, gevolgd door rogge en grasland, en vervolgens onbespoten mais. Binnen de bezochte habitats hadden foeragerende vogels een voorkeur voor kale grond wat de keuze voor met herbiciden bespoten maïs verklaart (hoewel de graslanden een groter aanbod van ongewervelde dieren hadden). De keuze voor bespoten maïs was waarschijnlijk de minst ongunstige optie binnen een sterk verarmd leefgebied.
The Ortolan Bunting Emberiza hortulana has suffered a general decline across much of Western Europe in recent decades. In Switzerland, only one population remains in sub-Mediterranean shrub-steppe on the south-facing slopes of the Rhone Valley (Valais). We aimed to collect data on foraging ecology of the last Swiss Ortolan Buntings during reproduction. All males showed a disproportionate use of conventional maize fields that had been treated with herbicides, while also exhibiting an avoidance of meadows and riparian vegatation. The observed patterns of habitat use may be driven by unavailability of optimal foraging habitat, with birds being forced to use the best of a poor set of options. Structurally, it was shown that birds foraged in areas with a high proportion of bare ground, as well as moderately dense overhead vegatation. These areas did not support higher arthropod abundance, suggesting that food accessibility rather than food abundance dictated habitat selection.
Breeding and wintering abundance of corn buntings Miliaria calandra in an agricultural landscape of Alentejo (southern Portugal) was assessed in relation to agricultural intensification and other environmental variables during 1994-1997. Bird abundance was lowest in intensively managed farmland in both seasons.