Increase in breeding bird abundance and diversity with semi-natural habitat in vineyard landscapes

Abstract

Agricultural expansion and intensification are major threats to biodiversity, and even some once common farmland bird species are now endangered. Wine-growing landscapes are intensively managed but can still be an attractive habitat for a wide range of species. However, only few bird species breed within vineyards and thus, semi-natural habitat types like hedges, woodland patches and grasslands are crucial for bird populations. We investigated how birds breeding in wine-growing areas are influenced by the surrounding landscape at three spatial scales: territories, sampling transects and landscapes. In the German wine growing region Palatinate, sixteen landscapes with a radius of 500 m were chosen spanning a gradient in the cover of semi-natural habitat. Bird territories were mapped along three transects of 500 m length in each landscape. We found 300 territories of 33 bird species. Positive effects of semi-natural habitat cover on birds were strongest at the transect scale, with almost proportional increase of species and territory numbers with the cover of semi-natural habitat. Most bird species selected territories that contained more semi-natural habitat than the landscape-wide average of 13.5%, but e.g. woodlark and linnet showed an opposite preference. In addition, the birds' community composition was influenced by the composition of the surrounding landscape. Most species were associated with semi-natural habitat types or built-up areas while vineyards had hardly any species associated with them. Our results suggest that in wine-growing landscapes, the decline in farmland birds can be reversed by the re-establishment of hedges, trees, woodland patches, traditional orchards and grassland areas. However, as preferences at the territory scale were species-specific, there is no uniform best solution for bird conservation in viticultural landscapes. Thus, landscape development should always be accompanied by experts that take the demands of existing and potential breeding birds into account.

Fig 1. Map of the study area in the vineyards west of the city of Landau in the federal state of Rhineland Palatinate.

The analyses were conducted on three different scales: on the scale of the entire landscapes (500 m radius), the transect scale (three transects per landscape with a buffer of 100 m radius) and the territory scale (100 m radius around territory centres).

Fig 2. Response of bird species richness and number of breeding bird territories to an increasing proportion of SNH on the landscape scale (a+b, n = 16) and the transect scale (c+d, n = 48).

Fig 3. Cover of SNH in the territories of the five most common unthreatened breeding birds (left, blackbird to chaffinch) and the five most common red-listed breeding birds (right, starling to woodlark).

The dashed line represents the overall cover of SNH averaged over the 16 landscapes (13.5%). *** P < 0.001, ** P < 0.01, * P < 0.05.

Fig 4. RDA plot showing differences in bird communities depending on the composition of the area around transects.

Red-listed species are shown in bold characters.