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1. Global warming is causing species to shift their ranges towards higher latitudes and elevations, leading to a reassembly of plant communities and associated community thermophilization (i.e. an increasing number or cover of thermophilic species, sometimes at the expense of mesic or cold-adapted species). Given the large variation typically observed in the magnitude and direction of range shifts, quantifying community thermophilization might provide a more sensitive method to detect climate change impacts within short time periods and across limited spatial extents, as it integrates range shifts across multiple species while also accounting for changes in abundance.

2. Here, we combined an assessment of (i) species-level range shifts and (ii) changes in community-inferred temperatures (thermophilization) along three mountain roads in Switzerland to ask whether plant communities have responded to a warming climate over a 10-year period, and whether community thermophilization is a sensitive metric for early detection of these changes.

3. We found a community thermophilization signal of +0.13°C over the 10-year study period based on presence-absence data only. Despite significant upwards shifts of species' upper range limits in the lower part of the studied elevational gradient and a decrease in species richness at high elevations, significant thermophilization was not detectable if community-inferred temperatures were weighted by species' covers. The low cover values of species that were gained or lost from local communities over the study period, together with their similar species-specific temperatures to resident species, explained the discrepancy between the thermophilization detected in cover-weighted versus unweighted models.

4. Synthesis. Our work shows that plant species are rapidly shifting to higher elevations along roadsides in the western Swiss Alps and that this translates into a detectable warming signal in plant communities within 10 years. However, the species-level range shifts and the community-level warming effect are mostly based on gained/lost species with low cover values, preventing the detection of community thermophilization signals when incorporating cover changes. We therefore recommend including unweighted approaches as an additional option for early detection of community-level responses to changing climate, ideally in combination with assessments of species-level range shifts.

Iseli, E., Diaz Zeugin, N., Brioschi, C., Alexander, J., & Lenoir, J. (2025). Early detection of plant community responses to climate warming along mountain roads. Journal of Ecology, 113, 2575–2589. https://doi.org/10.1111/1365-2745.70114

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

The conservation community sorely lacks a global indicator of change in insect populations. Given widespread insect declines, addressing this gap is key for conservation and policy targets. We suggest that butterfly monitoring programs can serve as the foundation for an effective global network of insect monitoring. To assess this potential, we bring together an international consortium and calculate a “Global Butterfly Index”using the Living Planet Index approach. Based on 10,386 population trends of 213 univoltine species, we found that overall declines in butterfly populations are predictable based on species traits. Our effort should pave the way for the development of a global network of butterfly population monitoring schemes. Since butterflies are the best monitored insects and have strong emotional value for the public, a global infrastructure for butterfly monitoring can be a flagship for insect conservation, informing policymaking and spurring societal transitions towards sustainable futures.

Riva, F., R.Schmucki, R.Cooke, et al. 2026. “Addressing Gaps in Butterfly Population Monitoring to Catalyze Global Insect Conservation.” Conservation Letters19, no. 2: e70037. https://doi.org/10.1111/con4.70037