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The Swiss Common Breeding Bird Monitoring (“Monitoring Häufige Brutvögel” MHB) is a long-term study organized by the Swiss Ornithological Institute. Its main goal is to collect data for estimating breeding population trends of relatively abundant and widespread species. Since 1999, 267 one-km squares laid out in a mostly systematic grid across all of Switzerland have been surveyed annually by skilled, mostly volunteer ornithologists. The sampling sites thus cover a wide range of typical Western European habitats, and an altitudinal range from 250 up to 2750 m above sea level. Bird populations are recorded using a simplified territory mapping protocol with two visits per square above the timberline and three elsewhere. Surveys are conducted during the breeding season (mid-April to early July) along a square-specific transect route that does not change over the years. A typical transect route is between 4 and 6 km long, and each visit usually lasts 3 to 4 h. The location of all visually or acoustically detected birds is recorded on topographical maps or using a smartphone app. Records that meet predefined criteria in terms of species-specific breeding period and observed behavior are retained for the subsequent step of territory delimitation. This is done automatically for most species by the program Autoterri since 2022 and was done manually before, with subsequent checks by an expert. This process finally results in an estimate of the total number of detected territories per species, square and year. The design also explicitly generates detection histories, consisting of two to three numbers that represent the number of territories found to be occupied during each respective visit, enabling the analysis with binomial N-mixture and site-occupancy models. The dataset currently covers the breeding seasons from 1999 to 2024 and includes 6852 site-by-year combinations with estimates of detected territory numbers. It covers 162 of the 166 bird species recorded at least once as potential breeders, excluding four species to prevent potential disturbance at nesting sites. Besides informing about population trends, data from the Swiss Common Breeding Bird Monitoring were used to illustrate several methodological developments in N-mixture, occupancy and related models and to answer scientific and applied questions. With its clearly defined survey method, the largely systematic distribution of its survey sites, and the long timespan covered, it is likely that this dataset will continue to make important contributions in biological and biostatistical research. Herewith, we make the annually updated data set available with a CC BY 4.0 license, allowing researchers and conservationists to use and analyze the data for their own research and conservation efforts.

Strebel, N., Wechsler S., Bühler B., Häfliger G., Keller V., Kéry M., Rogenmoser C., et al. 2025. Data of the Swiss Common Breeding Bird Monitoring Program. Ecology 106 (12): e70268. https://doi.org/10.1002/ecy.70268

Deposition of atmospheric N (nitrogen) is assumed to be a major cause of biodiversity decline in Europe. To date, few studies on the direct or indirect effects of N on bird species have been conducted. Using Swiss bird count data and habitat data, we analyzed the corre- lation of N deposition with numbers of territories of 112 breeding bird species. Fifty-five species had a negative correlation with N, and 21 had a positive correlation. Thirty-six species showed no clear linear relationship. Insectivorous and herbivorous species were more negatively associated with N deposition (insectivores: 23 species with well-supported negative correlation vs. 9 species with well-supported positive correlation; herbivores: 6 vs. 1) than omnivorous birds or birds feeding on vertebrates (2 with negative correlation vs. 2 with positive correlation and 1 with negative correlation vs. 1 with positive correlation, respectively). Species associated with forest (23 negative vs. 3 positive), human settlement and wetland (each 3 negative vs. 0 positive), and birds that could not be attributed to a single guild (3 negative vs. 1 positive) showed mainly a negative relationship with N depo- sition, whereas more positive than negative correlations were found for alpine (0 negative vs. 2 positive) and common farmland species (0 negative vs. 7 positive). Ground-nesting species were more negatively associated with N deposition (8 negative vs. 2 positive) than species that nest high aboveground (24 negative vs. 11 positive). The negative correlation of N deposition with territory numbers was slightly more pronounced in long-distance migrant species (9 negative vs. 3 positive) than in resident or short-distance migrants (23 negative vs. 10 positive). Rare species were excluded, likely biasing farmland bird results positively. We assumed that differences in the vegetation due to higher N inputs were the main cause for our results. Reduced plant diversity, altered vegetation structure, and more frequent mowing affect breeding habitat and availability of food (invertebrates and seeds) for birds. In Switzerland, airborne N deposition exceeds by far the critical loads for most ecosystems. Our results highlight the urgent need to reduce N deposition to protect a wide range of Swiss bird species.

Meichtry-Stier, K., Korner, P., Birrer, S., & Knaus, P. (2025). Effects of nitrogen deposition on territory numbers of breeding birds. Conservation Biology, 39, e70114. https://doi.org/10.1111/cobi.70114

We need landscape-scale approaches to design and manage agro-ecosystems that can sustain both agricultural production and biodiversity conservation. In this study, yield figures provided by 299 farmers served to quantify the energy-equivalents of food production across different crops in 49 1-km² landscapes. Our results show that the relationship between bird diversity and food energy production depends on the proportion of farmland within the landscape, with a negative correlation observed in agriculture dominated landscapes (≥ 64–74% farmland). In contrast, neither typical farmland birds nor butterflies showed any significant relationship with total food energy production. We conclude that in European temperate regions consisting of small-scale, mixed farming systems (arable and livestock production), productivity and biodiversity conservation may not be purely antagonistic, particularly when (semi-)natural habitats make up a large fraction of the landscape (≥ 20%).

Zingg, S., Grenz, J. & Humbert, J.-Y. (2024). Food production and biodiversity are not incompatible in temperate heterogeneous agricultural landscapes. Front. Sustain. Food Syst. 8:1377369. doi: 10.3389/fsufs.2024.1377369

Als Folge des Klimawandels etablieren sich immer mehr wärmeliebende Arten in Schweizer Gewässern. Da wirbellose Kleinlebewesen als Bioindikatoren für die Qualität von Fliessgewässern dienen, könnte diese Entwicklung die biologische Gewässerbeurteilung verfälschen. Simulationen zeigen, dass die Vielfalt der Wirbellosen tatsächlich zunehmen wird, jedoch auf Kosten kälteliebender Arten. Soweit sich das beurteilen lässt, sind die verwendeten Indizes aber robust genug, um ihre Aussagekraft zur Gewässerqualität für die nächsten Jahrzehnte zu behalten.

Vorburger, C., Khaliq, I., Ramampiandra, E. C., Narwani, A., & Schuwirth, N. (2024). Biologische Gewässerbeurteilung im Klimawandel. Aqua & Gas, 104(10), 60-65.