Losses and gains of fallows drive farmland bird populations over three funding periods of the EU Common Agricultural Policy

Fallow land provides habitat for threatened and declining farmland biodiversity. Policy change under the EU's Common Agricultural Policy (CAP) has been driving the area of fallows over the past decades and influenced trends in farmland biodiversity. We analyzed the impact of changes in fallow area across Germany on species richness and abundance of farmland birds over three CAP funding periods. We examined whether responses to fallow land area were modulated by species habitat preferences and landscape complexity. We combined spatial data on fallow land area from three agricultural censuses in Germany (2007, 2010 and 2016) with country-wide, annual monitoring data on farmland birds. Farmland bird species richness and the abundance of edge- and field-breeders responded positively to increases in fallows. The effect of fallows on bird richness was strongest at intermediate levels of landscape complexity. There was support for an increasing effect strength of fallow land area on field-breeders' abundance with increasing landscape complexity. We conclude that the loss of fallows in the period 2007 to 2016 resulted in strong declines of farmland birds. We predict that a future increase of the proportion of fallow land to 4%, as envisaged in the post-2020 CAP for Germany, will result in an average increase of 7% in farmland bird species richness and of 11% in average farmland bird abundance compared to 2016, but will depend on species-specific habitat preferences. Increasing the proportion of fallow land will be a key lever to stabilize and revert negative farmland bird population trends. An increase of fallow area in all but the least complex landscapes will boost farmland bird richness and abundance of field breeders. Increasing the proportion of fallow land to 4% is projected to, on average, bring farmland bird richness and abundance back to the levels observed in 2007 acknowledging that farmland bird populations were already severely depleted in 2007. A more ambitious expansion of fallow land towards 10%, such as in the context of the EU Biodiversity Strategy for 2030, should be targeted towards areas that experienced the strongest loss of fallows and towards landscapes with intermediate structural complexity.

Landscape-Scale Effects of Irrigation on a Dry Cereal Farmland Bird Community

Landscape modification and habitat fragmentation are one of the major current threats to biodiversity. The main source of habitat fragmentation is the loss of focal habitat area, but changes in the composition of the surrounding landscape also have a direct effect on biodiversity. These changes may lead to the loss of some species but also may favor species replacement. Farmland birds in Europe are affected by landscape changes due to farmland intensification, such as the spread of irrigation, which may occur at different spatial scales. As irrigation is expected to increase in the coming years, which may affect protected areas, it is necessary to evaluate its potential consequences over focal biodiversity. In this study we assess the relationship between the increase of irrigated land at different spatial scales and changes in a dry cereal farmland bird community, bird abundance and species richness, using generalized linear models. We used a dry cereal farmland affinity index to describe the level of community specificity for dry cereal farmland. The increase in irrigated tree orchards produced an increase in species richness up to 500 m away from the irrigated area, which had a negative effect on the dry cereal farmland bird community, by triggering a replacement of specialist by generalist species. Our results show the importance of landscape-scale effects of irrigation occurring outside protected areas on the farmland bird community inside Natura 2000 sites, as well as how these effects are detected even at long distances from the disturbance source.

Modelling the Impacts of Habitat Changes on the Population Density of Eurasian Skylark (Alauda arvensis) Based on Its Landscape Preferences

The dramatic decline of the abundance of farmland bird species can be related to the level of land-use intensity or the land-cover heterogeneity of rural landscapes. Our study area in central Europe (Hungary) included 3049 skylark observation points and their 600 m buffer zones. We used a very detailed map (20 × 20 m minimum mapping unit), the Hungarian Ecosystem Basemap, as a land-cover dataset for the calculation of three landscape indices: mean patch size (MPS), mean fractal dimension (MFRACT), and Shannon diversity index (SDI) to describe the landscape structure of the study areas. Generalized linear models were used to analyze the effect of land-cover types and landscape patterns on the abundance of the Eurasian skylark (Alauda arvensis). According to our findings, the proportions of arable land, open sand steppes, closed grassland patches, and shape complexity and size characteristics of these land cover patches have a positive effect on skylark abundance, while the SDI was negatively associated with the skylark population. On the basis of the used statistical model, the abundance density (individuals/km*) of skylarks could be estimated with 37.77% absolute percentage error and 2.12 mean absolute error. We predicted the skylark population density inside the Natura 2000 Special Protected Area of Hungary which is 0–6 individuals/km* and 23746 ± 8968 skylarks. The results can be implemented for the landscape management of rural landscapes, and the method used are adaptable for the density estimation of other farmland bird species in rural landscapes. According to our findings, inside the protected areas should increase the proportion, the average size and shape complexity of arable land, salt steppes and meadows, and closed grassland land cover patches.

Avian richness of the Basanta Protected Forest, far-western lowland Nepal: Implication for conservation

Birds are important components of biodiversity and acts as an indicator of habitat quality, productivity and stability. This study aimed to document species richness and assess the temporal distribution pattern of globally threatened bird species in the Basanta Protected Forest (BPF), one of the largest corridor forests which connects Dudhwa National Park (India) with protected areas of western lowland Nepal. During study period of ten years from 2010 to 2019, a total of 381 bird species from 78 families of 19 orders were recorded. Order Passeriformes had the highest species richness (n=180) followed by order Accipitriformes and Charadriiformes. Among the families, the family Muscicapidae had the highest species richness (n=31), followed by Accipitridae and Anatidae. Majority of bird recorded were forest bird followed by wetland and farmland bird species. Fifteen globally threatened species like red-headed vulture (Sarcogyps calvus), white-rumped vulture (Gyps bengalensis), slender-billed vulture (Gyps tenuirostris), steppe eagle (Aquila nipalensis) and Egyptian vulture (Neophron percnopterus) were recorded in the BPF. Extensive avian survey in the BPF is important for further exploration of avian community along with its driving factors, which might play a crucial role in developing baseline information and implementing conservation implications.