Anders P. Tøttrup

School‐based citizen science holds great potential for expanding biodiversity knowledge while engaging young people in authentic scientific practices. This is particularly important for revealing ‘dark biodiversity’, defined as the vast yet often overlooked biodiversity that remains hidden due to its small size or cryptic nature, including microorganisms. Here, we showcase findings from a nationwide citizen science project called ‘The Mass Experiment’, where 27,710 school students helped reveal Denmark's dark biodiversity, including bryophytes, lichens, and tardigrades hiding in plain sight. We provided teachers with professional support to facilitate inquiry‐based learning. Students in turn conducted standardized fieldwork in local ecosystems, collected samples and completed laboratory exercises using provided instructional materials and following their teachers' guidance. Identity of the student‐collected specimens was then verified by taxonomic experts at the Natural History Museum Denmark. The project generated 4258 biodiversity digital records uploaded to the Danish biodiversity portal, including 69 bryophyte species, 29 lichen taxa (or 28 lichen species), and 55 tardigrade species, 41 of which were new to Denmark and at least nine to science. Students successfully identified most target bryophyte and lichen species using the project's guides. Survey responses from more than 1000 students and 400 teachers revealed high levels of engagement, increased interest in natural sciences, and strong appreciation for contributing to real research, although some teachers found aspects of the protocol overly complex. The project also achieved substantial public visibility, with 87 media features and numerous outreach activities. Overall, this study demonstrates that large‐scale, school‐based citizen science can simultaneously produce high‐quality biodiversity data and foster meaningful educational outcomes, revealing hidden biodiversity while promoting environmental literacy, enriching museum collections and raising public awareness. In this way, the project also supports the Sustainable Development Goals proposed by the United Nations by bridging education, science and society. Read the free Plain Language Summary for this article on the Journal blog.

BACKGROUND: The preferred treatment for patients with medically refractory ulcerative colitis is a restorative proctocolectomy with IPAA. The transanal approach has been adopted in many centers; however, the plane of dissection, number of surgical stages, and type of anastomosis differ, resulting in substantial heterogeneity in published studies. OBJECTIVE: We aimed to compare short-term surgical outcomes of modified transanal total mesorectal excision and transanal close rectal dissection in the formation of transanal IPAA. DESIGN: Retrospective cohort study. SETTINGS: Two referral centers responsible for transanal IPAA in Denmark. PATIENTS: Patients older than 18 years with ulcerative colitis undergoing transanal IPAA from 2015 to 2023. MAIN OUTCOME MEASURES: Surgical complications in the first 30 postoperative days as registered in the surgical records. RESULTS: A total of 176 patients underwent transanal IPAA at the 2 centers: 78 patients with close rectal dissection and 98 patients with modified transanal total mesorectal excision. There was no significant difference in complications, including anastomotic leak (3 [4%] and 4 [4%] patients) and intra-abdominal abscesses (2 [3%] and 2 [2%] patients). LIMITATIONS: The data were collected retrospectively and relied on uniformly reported complications. We did not calculate a study power but included all consecutive patients. CONCLUSIONS: There were comparable complications, including anastomotic leaks and intra-abdominal abscesses in the 2 groups, indicating they are equally safe procedures. See Video Abstract . RESULTADOS QUIRÚRGICOS A CORTO PLAZO TRAS PROCTOCOLECTOMÍA RESTAURADORA TRANSANAL CON ANASTOMOSIS ILEOANAL CON RESERVORIO: COMPARACIÓN ENTRE DISECCIÓN RECTAL CERRADA Y ESCISIÓN MESORRECTAL TOTAL MODIFICADA: ANTECEDENTES: El tratamiento de elección para pacientes con colitis ulcerosa refractaria al tratamiento médico es la proctocolectomía restauradora con anastomosis ileoanal con reservorio. El abordaje transanal se ha adoptado en muchos centros; sin embargo, el plano de disección, el número de etapas quirúrgicas y el tipo de anastomosis varían. Esto genera heterogeneidad en los estudios existentes. OBJETIVO: Comparar los resultados quirúrgicos a corto plazo de la escisión mesorrectal total transanal modificada y la disección rectal transanal cerrada en la formación de la anastomosis ileoanal con reservorio transanal. DISEÑO: Estudio de cohorte retrospectivo. ÁMBITO: Dos centros de referencia responsables de la anastomosis ileoanal con reservorio transanal en Dinamarca. PACIENTES: Pacientes mayores de 18 años con colitis ulcerosa sometidos a anastomosis ileoanal con reservorio transanal entre 2015 y 2023. PRINCIPALES MEDIDAS DE RESULTADO: Complicaciones quirúrgicas durante los primeros 30 días postoperatorios, según consta en los registros quirúrgicos. RESULTADOS: Un total de 176 pacientes se sometieron a anastomosis ileoanal transanal con reservorio ileal en los dos centros: 78 pacientes con disección rectal cerrada y 98 pacientes con escisión mesorrectal total transanal modificada. No se observaron diferencias significativas en las complicaciones, como la fuga anastomótica (3 pacientes [4%] y 4 [4%]) o los abscesos intraabdominales (2 pacientes [3%] y 2 pacientes [2%], respectivamente). LIMITACIONES: Los datos se recopilaron retrospectivamente y se basaron en las complicaciones notificadas de forma uniforme. No se calculó la potencia estadística del estudio, pero se incluyeron todos los pacientes consecutivos. CONCLUSIONES: Las complicaciones fueron comparables en cuanto a fugas anastomóticas y abscesos intraabdominales en ambos grupos, lo que indica que ambos procedimientos son igualmente seguros. (AI-generated translation )

Migratory songbirds have an internal circannual genetic programme that controls the timing and extent of migratory flight activity, as demonstrated by experiments with birds held in cages. We used multisensor data loggers to record the timing and duration of all migratory flights during the annual cycle of 15 free-living individuals of red-backed shrikes Lanius collurio . Annual actograms unexpectedly revealed that the nocturnal migratory flights of the shrikes were organized in a highly structured way, with flights aggregated into segments that could be readily identified for all individuals, showing low variability and thus high consistency between individuals. These results suggest that the execution of migratory flights is under a high degree of control according to a rather detailed internal travelling plan for the annual migration cycle. Potentially, the control of migratory flight under natural conditions depends on a complex feedback process where external cues associated with the geographic, temporal and nutritional situation of the bird are required for the internal programme to properly regulate the successive segmental flight steps of the migratory journey. This would mean that the internal/genetic programme for control of bird migration is much more dynamic and complex than hereto assumed.

Climatic changes are causing general ecosystem changes and species-specific range shifts. To increase our understanding of climate change effects on avian trends and range shifts, this study investigates long-term breeding bird population trends in the pristine Høstemark Forest, Denmark, from 1991 to 2024, in the context of climate change and biodiversity loss. Using territory mapping data from unmanaged pristine forest and national point count data, we examined whether climate-group classifications (leading-edge, neutral, trailing-edge) predict population trends and how a high-quality habitat buffers against climate-driven shifts. Results show significant declines in total bird territories since 1991, while forest-specific bird species abundance remained stable in the Høstemark Forest. Trailing-edge species declined both locally and nationally, while leading-edge species increased locally but not significantly at the national level. Climate-neutral species exhibited local declines despite stable national trends. Species turnover rate appeared to occur more rapidly in the Høstemark Forest compared to the national scale, with both losses of trailing-edge species and gains in leading-edge species. However, despite its ecological quality and stability, the Høstemark Forest experienced a decline in overall bird abundance, suggesting that even pristine habitats can be vulnerable to biodiversity loss, potentially driven by climate change, isolation, and edge effects.

Partnerships between the public and researchers in participatory research projects are shifting towards co-creational models. Within archaeology, traditional projects involve the public through artefact treatment and data handling and entry. In the project discussed herein, we aimed to fully engage participants (high school students and teachers) in the research process using advanced scientific methods. We introduce a novel co-creational framework, which actively involved high school students in archaeological research. In the initial phase, we collaborated with local museums and high school teachers to integrate archaeological expertise with educational objectives in our participatory project setup. High school teachers facilitated curriculum connections, while museums contributed valuable materials and local archaeological insights. In the final study programme, students participated in hands-on laboratory work, using both a morphological approach and Zooarchaeology by Mass Spectrometry (ZooMS) to analyse archaeological leather samples. Standardised protocols were adapted to match student capabilities while maintaining scientific validity. A total of 3,319 high school students handled 917 different archaeological objects and analysed 3,900 samples. Based on the highest quality result with 3–5 replicates for each object, we achieved taxonomic identifications for 95% of the objects. Evaluation of participating students’ outcomes showed strong engagement in the scientific process, demonstrating the value of co-creational partnerships in enhancing both research and educational outcomes. Our model fosters interdisciplinary thinking and scientific skills among students while establishing one of the largest archaeological datasets globally. The project’s cross-disciplinary approach and robust validation methods ensure high-quality data for future archaeological research, highlighting the powerful potential of public involvement in scientific endeavours. Moving forward, expanding the range of materials analysed could broaden participation and further enrich both research and educational experiences.

The early life movement patterns of long-lived, large raptors, such as the white-tailed eagle (Haliaeetus albicilla), remain largely unexplored. In this study, we have tracked 22 individuals of white-tailed eagles hatched in Denmark to investigate key parameters, including survival rates, causes of death, nest site fidelity, geographical distribution, and dispersal behaviors. Our analyses are based on approximately 340,000 GPS/GSM telemetry positions from the 22 individuals. We found that survival rates were lower in the first year of life, especially among females, but increased in subsequent years. The primary causes of death were wind turbine collisions and avian influenza. Movement analyses revealed that juvenile eagles frequented nest sites in August and September, with females showing earlier exploratory flights and dispersal. Both males and females spent most of their first calendar year near their nest sites. In the second calendar year, a significant proportion of their time was spent at well-known white-tailed eagle resting areas in Denmark, as well as visiting neighboring countries. Notably, one individual set a new distance record for a Danish GPS-tagged white-tailed eagle, venturing at least 1750 km away from its nest site to visit Sweden, Finland, Russia, and Norway. Our results, indicating that juvenile white-tailed eagles continue to utilize nest sites into September, suggest an extension of the recommended time period for nest protection zones provided by BirdLife Denmark (DOF).

Most migratory birds return every year to the same breeding sites and some species show a similarly high fidelity to wintering grounds as well. Fidelity to stopover sites during migration has been much less studied and is usually found to be lower. Here, we investigate site fidelity and distance to previously visited sites throughout the annual cycle in the common cuckoo, a nocturnal trans‐Saharan migrant, based on satellite‐tracking data from repeated annual migrations of thirteen adult males. All birds (100%) returned to the same breeding grounds, with a median shortest distance of only 1 km from the locations in previous year. This was in strong contrast to a much lower and much less precise site fidelity at non‐breeding sites during the annual cycle: In only 18% of the possible cases in all non‐breeding regions combined, did the cuckoos return to within 50 km of a previously visited non‐breeding site, with no significant differences among the main staging regions (Europe in autumn, Sahel in autumn, wintering in Central Africa, West Africa in spring, Europe in spring). The shortest distance to a previously visited non‐breeding site differed among the staging regions with median shortest distances for the longest stopovers of 131 km [2;1223] (median [min;max]) in Europe, 207 km [1;2222] in Sahel in autumn and 110 km [0;628] in Central Africa. The distance to a previously visited staging site decreased with the time spent at the stopover in a previous year. Understanding the drivers of recurrence and site selection in migratory birds are important for guiding conservation efforts in this group but further studies are needed to establish whether the patterns observed in cuckoos are general among terrestrial migrants with continuous distribution of habitat.

Anthropogenic land cover change is a major driver of biodiversity loss, with urbanisation and farmland practices responsible for some of the most drastic modifications of natural habitats. The relative importance of different land covers for shaping insect communities, however, is unclear. This study examines the effect of urban and farmland covers, along with land cover heterogeneity, at a landscape scale on species richness, evenness and biomass of flying insects using citizen science carnet sampling across Denmark. Increasing urban cover had a negative effect on insect richness but an even stronger negative effect on biomass. Increased land cover heterogeneity did not mitigate the negative effect of urban cover. Insect assemblages also became more even with increased urban cover. Farmland cover had no significant effect on insect richness, evenness or biomass. Based on our findings, the urban cover has a strong negative impact on insect communities, indicating that urbanisation could contribute to insect declines. Moreover, our findings indicate that insect loss occurs more through loss of biomass than loss of species, which may affect the ecosystem‐level consequences of urbanisation.

Climate change affects important biological processes, bird migration phenology being a particular well-documented one. While spring migration have been found to advance by numerous studies, autumn migration is less studied and show more variable change in timing. Few studies of autumn migration are based on data from after 2000, leaving the last two decades to be relatively less studied. Here, we investigate recent change in autumn migration phenology of European passerines. The most recent available bird ringing data from Denmark is used to analyse phenological change of median and late migration of 14 passerine migrants between 2003–2021. We find an overall delay of autumn migration, mainly driven by short-distance migrants. All short-distance migrants, one out of five medium-distance and three out of five long-distance migrants delay autumn migration. None of the included species advance autumn migration significantly. As climate change has continuously resulted in milder conditions in north-western Europe, we expect this to cause further effects on migration phenology also in recent decades. Our results provide novel insight into recent migration phenology trends, and the observed delay in long-distance migrants may illustrate a changed response to climate change.