© Roman Graf
Landscape changes and avian population trends in the Engadin
Over the last years, agricultural intensification has also occurred in the lower Engadin, an alpine valley long known for its traditional and low-intensity land use. The Swiss Ornithological Institute is now investigating to what extent the landscape has really changed and what the consequences for bird populations are.
- Quantifying recent changes in land use and bird populations in one of the most important regions of Switzerland for agricultural bird species
- Presenting scenarios of future trends of the landscape and biodiversity within the general framework of different agricultural policies
- Documenting the consequences of various instruments relevant to landscape development (agri-environment schemes, ameliorations, irrigation)
- Setting up strategies to improve low-quality areas and to maintain as yet little disturbed areas
- Establishing arguments for redirecting the system of direct subsidies into a bird-friendly manner
- Discussing the results with local and regional politicians and publishing articles in scientific and popular journals (including tourists media)
- Data screening, evaluation of methods, lobbying (2009)
- Standardizing field methods
- Acquiring third-party funds
- Repeating censuses of breeding birds on selected study plots
- Censuses of vegetation, landscape and habitat structures on the same plots
- Data analysis
- Communicating results to the public, politicians and stakeholders (agriculture, tourism), publishing articles
The agricultural landscape of the Engadin, an inner-alpine valley in south-eastern Switzerland, is characterized by a great variety of habitats and therefore hosts an immense biodiversity. The open and semi-open habitats of inner-alpine valleys are still home to a group of bird species, which by now occurs in the rest of Switzerland, if at all, at only very low densities. This avian community depends on a sustainable, low-intensity agricultural land use, as it has been traditionally applied in the Engadin until quite recently. In recent decades, however, this land use practice has come under pressure. In areas particularly favourable for agriculture, intensity of land use is increasing. The consequences of this intensification for the landscape and the bird community has not been studied in the Engadin yet. Nevertheless, it is undisputed that recent changes in occupancy patterns and density of whinchats are related to the land use intensification. It is not known if other species of agricultural landscapes have suffered from similar changes. Repeating censuses on 38 plots between Martina and Maloja already studied in 1987/88 in terms of vegetation, land use intensity and breeding birds offers the unique opportunity to document landscape change and associated consequences for agricultural birds over two decades.
Distinct changes were found in agricultural land use, vegetation and birds. As an example, vegetation types of nutrient-poor locations have declined in favour of intensively used meadows and pastures. The ratio of meadows to pastures has shifted towards grazed areas. Even though the neglected land area has increased by 21 %, its share relative to the total land area is still relatively low (8.4 %). Extensively used areas have decreased by 15 %, which again was primarily beneficial for intensively used areas. This development takes places primarily in farmland close to settlements in the Lower Engadine and in the valley bottoms of the Upper Engadine. In 71 % of the assessed areas, a shift towards a seasonally earlier mowing was recorded. Our observations indicate that structural diversity, in particular of hedges and bushes, has considerably increased in the montane zone.
Meadow breeding bird species have dramatically declined (skylark -58 %, tree pipit -47 %, whinchat -46 %). Populations of meadow breeding birds have changed the most in places, where also vegetation and agricultural land use have been most strongly altered. Relatively good populations are left in the high montane meadow zone. Within the framework of regional habitat connectivity programmes, late mowing regimes could be agreed upon on relative large areas.
The red-backed shrike has also strongly declined. In contrast, a strong increase has been noted in the Eurasian blackcap. Small population increases were observed for green woodpecker, garden warbler, Western Bonelli’s warbler, European goldfinch and yellowhammer. Species of conservation concern have mostly declined, indicators of the environmental objectives in the agricultural sector (EOAS) as an example by approx. one third.
Les installations d'irrigation, causes de l'intensification de l'exploitation en Engadine.
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