Birds of prey, owls and falcons are widely used as sentinel species in raptor biomonitoring programmes. A major current challenge is to facilitate large-scale biomonitoring by coordinating contaminant monitoring activities and by building capacity across countries. This requires sharing, dissemination and adoption of best practices addressed by the Networking Programme Research and Monitoring for and with Raptors in Europe (EURAPMON) and now being advanced by the ongoing international COST Action European Raptor Biomonitoring Facility. The present perspective introduces a schematic sampling protocol for contaminant monitoring in raptors. We provide guidance on sample collection with a view to increasing sampling capacity across countries, ensuring appropriate quality of samples and facilitating harmonization of procedures to maximize the reliability, comparability and interoperability of data. The here presented protocol can be used by professionals and volunteers as a standard guide to ensure harmonised sampling methods for contaminant monitoring in raptors.

Aim: The tinder fungusFomes fomentariusis a pivotal wood decomposer in European beechFagus sylvaticaforests. The fungus, however, has regionally declined due to centuries of logging. To unravel biogeographical drivers of arthropod communities associated with this fungus, we investigated how space, climate and habitat amount structure alpha and beta diversity of arthropod communities in fruitbodies ofF. fomentarius.Location: Temperate zone of Europe.Taxon: Arthropods.Methods: We reared arthropods from fruitbodies sampled from 61 sites throughout the range of European beech and identified 13 orders taxonomically or by metabarcoding. We estimated the total number of species occurring in fruitbodies ofF. fomentariusin European beech forests using the Chao2 estimator and determined the relative importance of space, climate and habitat amount by hierarchical partitioning for alpha diversity and generalized dissimilarity models for beta diversity. A subset of fungi samples was sequenced for identification of the fungus’ genetic structure.Results: The total number of arthropod species occurring in fruitbodies ofF. fomentariusacross European beech forests was estimated to be 600. Alpha diversity increased with increasing fruitbody biomass; it decreased with increasing longitude, temperature and latitude. Beta diversity was mainly composed by turnover. Patterns of beta diversity were only weakly linked to space and the overall explanatory power was low. We could distinguish two genotypes ofF. fomentarius,which showed no spatial structuring.Main conclusion: Fomes fomentariushosts a large number of arthropods in European beech forests. The low biogeographical and climatic structure of the communities suggests that fruitbodies represent a habitat that offers similar conditions across large gradients of climate and space, but are characterized by high local variability in community composition and colonized by species with high dispersal ability. For European beech forests, retention of trees withF. fomentariusand promoting its recolonization where it had declined seems a promising conservation strategy.

Aphanomyces astaci infection is the cause of crayfish plague in European crayfish. Here the virulence of an A. astaci As strain isolated from apparently healthy stone crayfish (Austropotamobius torrentium) from Slovenia was compared to that of the Psl-Puujärvi A. astaci isolate in 3 crayfish species: noble crayfish (Astacus astacus), signal crayfish (Pacifastacus leniusculus) from Finland and stone crayfish from Slovenia. All 3 crayfish species were challenged with PsI-Puujärvi A. astaci and succumbed to crayfish plague, with both noble crayfish and stone crayfish showing 100% mortality, while 25% of the signal crayfish died during the challenge. In comparison, the As-Slovenia A. astaci isolate was pathogenic for noble crayfish but not for signal crayfish or stone crayfish. This finding suggests that A. astaci virulence could be species specific and a strain from latent A. astaci infection in one native European crayfish species could be detrimental to other native European crayfish species.

Capsule: Territory monitoring using playback of calls is a reliable approach for assessing population trends of Tawny Owls Strix aluco, particularly when human resources are limited or survey areas are difficult to access. Aims: To explore whether response calls of Tawny Owls towards broadcast conspecific and heterospecific male owl playback calls would provide similar estimates of population size and trends over time as nest-box monitoring. Methods: Between 1998 and 2017, Tawny Owls were monitored in a predominantly forested area of central Slovenia. Throughout the year, territories were monitored using a playback protocol comprising silent listening during five minutes before and after ten minutes of broadcasting male Tawny Owl. Seasonal variation in response rate was examined and results from the playback method were compared to data on occupancy rate of nest-boxes. Results: Territory monitoring using playback calls showed a similar direction of population trends as nest-box monitoring but a different population dynamics pattern. The overall response rate in occupied territories to conspecific playback calls at first visits was 70%. This was significantly higher than for heterospecific playback calls and the frequency of spontaneous vocalizations. The response rate to conspecific playback calls when including two visits rose to nearly 90%. There was no difference in response rate between seasons. The average time to respond to conspecific playback calls was five minutes. Conclusions: Compared to nest-box monitoring of breeding pairs, territory monitoring of breeding and non-breeding Tawny Owls using playback provides a robust and cost-effective method for monitoring. We recommend conducting territory monitoring between January and May during the breeding season, with two visits to each site using conspecific playback of territorial male hoot calls using the 5 + 10 + 5 minutes protocol.

To address the decline in biodiversity, international cooperation in monitoring of threatened species is needed. Citizen science can play a crucial role in achieving this challenging goal, but most citizen science projects have been established at national or regional scales. Here we report on the establishment and initial findings of the European Stag Beetle Monitoring Network (ESBMN), an international network of stag beetle (Lucanus cervus) monitoring schemes using the same protocol. The network, started in 2016, currently includes 14 countries (see results) but with a strong variation in output regarding the number of transects (148 successful transects in total) and transect walks (1735). We found differences across European regions in the number of stag beetles recorded, related to phenology and temperature, but not for time of transect start. Furthermore, the initial experiences of the ESBMN regarding international cooperation, citizen science approach, and drop-out of volunteers is discussed. An international standardised protocol that allows some local variation is essential for international collaboration and data management, and analysis is best performed at the international level, whereas recruiting, training, and maintaining volunteers is best organised locally. In conclusion, we appeal for more joint international citizen science-based monitoring initiatives assisting international red-listing and conservation actions.