Linking agricultural policies to population trends of Swedish farmland birds in different agricultural regions

Abstract

Summary1. The widespread declines of farmland birds have generally been linked to agricultural intensification. We tested the hypotheses that (i) changes in agricultural policy, through its effects on agricultural intensification and (ii) regional differences in agricultural intensification affect temporal and spatial population trends of farmland birds in Sweden. 2. We analysed regional bird population trends (1976 -2003) for seven common farmland bird species: the migratory lapwing Vanellus vanellus , skylark Alauda arvensis , starling Sturnus vulgaris and linnet Carduelis cannabina and the resident tree sparrow Passer montanus , house sparrow P. domesticus and yellowhammer Emberiza citrinella . We identified three periods of agricultural policy in Sweden between 1976 and 2003: the intensification period (i.e. 1976-87; promoting increased production), the set-aside period (1987-95; promoting extensification of farming) and the Common Agricultural Policy (CAP) period (1995 -2003; promoting increased production). Population trends were compared between three types of Swedish farmlands: open plains (intensive farming with a marked intensification), mosaic farmlands (i.e. farmland-dominated forest mosaics, less intensive farming, but show moderate intensification) and forest regions (i.e. forest-dominated farmlands with low intensity farming and extensification/abandonment). 3. The four migrants displayed clear significant trend switches between the policy periods, with declines in the 'intensification period' and the 'CAP period' and less negative or even positive population trends in the 'set-aside period'. The population trends of the three resident species showed no clear pattern in relation to agricultural policy periods. 4. All species except tree sparrow displayed significantly different population trends between farmland regions. Four species (lapwing, skylark, linnet and house sparrow) declined most in the open plains and the forest regions, whereas two species (starling and yellowhammer) declined most in the mosaic farmlands. 5. Synthesis and applications. Large-scale changes in agriculture policy have a strong potential to change the present poor state of farmland biodiversity as shown by the generally positive population trends in the 'set-aside period'. It also suggests extensification to be beneficial to farmland birds. However, in regions of low profitability and an already ongoing extensification, a further extensification will lead to loss of both farmland habitat and bird diversity. In such regions mixed farming needs to be retained and hence should be supported.

The role of fallow in habitat use by the Lesser Kestrel during the post-fledging period: inferring potential conservation implications from the abolition of obligatory set-aside

“…Numerous studies on habitat use in migratory farmland birds have shown that fallow is an important habitat during the breeding and winter seasons (e.g., Delgado and Moreira 2000;Silva et al 2004;Wretenberg et al 2007). Whether fallow is also important during the post-fledging period is not known.…”

The demography of Yellow WagtailsMotacilla flavaon abandoned fields in northern European Russia

“…This has been caused mainly by a decrease in the diversification of the landscape linked to the elimination of uncultivated areas and agricultural intensification (Smart et al 2000, Orłowski 2005, Donald et al 2006, Wretenberg et al 2007. In contrast, in Eastern Europe, political and economic transformation has often caused the degradation of agriculture and the appearance of a large number of abandoned fields.…”

Wet Grasslands as a Green Infrastructure for Ecological Sustainability: Wader Conservation in Southern Sweden as a Case Study

“…In southern Sweden traditional farming practices based on animal husbandry and the associated large area of mowed and grazed wet grasslands, which provided habitats for many species, have been turned into intensive cropping systems [22,23]. Today, the remaining wet grasslands are dependent on environmental subsidies to maintain livestock grazing and mowing [24].…”