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It is widely assumed that spillover of alien parasites to native host species severely impacts naïve populations, ultimately conferring a competitive advantage to invading hosts that introduced them. Despite such host-switching events occurring in biological invasions, studies demonstrating the impact of alien macroparasites on native animal hosts are surprisingly few. In Europe, native red squirrels (Sciurus vulgaris) are replaced by introduced North American grey squirrels (S. carolinensis) mainly through resource competition, and, only in the United Kingdom and Ireland, by competition mediated by a viral disease. In Italy such disease is absent, but spillover of an introduced North American nematode (Strongyloides robustus) from grey to red squirrels is known to occur. Here, we used long-term (9 years) capture-mark-recapture and parasitological data of red squirrels in areas co-inhabited by grey squirrels in Northern Italy to investigate the impact of this alien helminth on naïve native squirrels’ body mass, local survival, and reproduction of females. We found no negative effect of the alien parasite on body mass or reproductive success, but intensity of infection by S. robustus reduced survival of both male and female squirrels. Significantly, survival of squirrels co-infected by their native nematode, Trypanoxyuris sciuri, was less affected by S. robustus, suggesting a protective effect of the native helminth against the new infection. Hence, we demonstrate that alien S. robustus spillover adds to the detrimental effects of resource competition and stress induced by grey squirrels, further reducing the fitness of the native species in the presence of the invasive competitor.

Animal space use is affected by spatio-temporal variation in food availability and/or population density and varies among individuals. This inter-individual variation in spacing behaviour can be further influenced by sex, body condition, social dominance, and by the animal’s personality. We used capture-mark-recapture and radio-tracking to examine the relationship between space use and personality in Eurasian red squirrels (Sciurus vulgaris) in three conifer forests in the Italian Alps. We further explored to what extent this was influenced by changes in food abundance and/or population density. Measures of an individual’s trappability and trap diversity had high repeatability and were used in a Principal Component Analysis to obtain a single personality score representing a boldness-exploration tendency. Males increased home-range size with low food abundance and low female density, independent of their personality. However, bolder males used larger core-areas that overlapped less with other males than shy ones, suggesting different resource (food, partners) utilization strategies among personality types. For females, space use-personality relationships varied with food abundance, and bolder females used larger home ranges than shy ones at low female density, but the trend was opposite at high female density. Females’ intrasexual core-area overlap was negatively related to body mass, with no effect of personality. We conclude that relationships between personality traits and space use in free-ranging squirrels varied with sex, and were further influenced by spatio-temporal fluctuations in food availability. Moreover, different personality types (bold-explorative vs. shy) seemed to adopt different space-use strategies to increase access to food and/or partners.

Mounting evidence indicates the non‐consumptive effects of predators significantly impact prey physiology, ecology and behaviour. Passerine birds experience adverse effects on nesting and reproductive success when in proximity to predators. Fear of predators is context‐dependent and influenced by hunting habitats and foraging strategies. While some bat species prey on birds, the greater noctule (Nyctalus lasiopterus) stands out by specialising in avian prey, especially during peak bird migration. N. lasiopterus is thought to seize avian prey in flight, but direct evidence is lacking. If birds were taken from nests, they would likely avoid nesting near these bats. However, no observations support this view. This study documents the successful reproduction of Eurasian blue tits (Cyanistes caeruleus) nesting alongside a colony of approximately 25 greater noctules. This bird species is a prey species for greater noctules in Italy. Over about 1 month (April–May 2023), we observed parent birds provisioning food to chicks, with at least two chicks alive and fed outside the tree cavity by the end of the period. While acknowledging the limitations of a single observation, we propose that this previously unknown behaviour indirectly supports the idea that greater noctules only capture avian prey in flight, not within confined spaces. This observation challenges the perception that these bats pose a threat when sharing roosting spaces in trees, as evidenced in our observed case. We hope this novel observation inspires future research on variations in bird nesting behaviour and reproductive success in the presence of bird‐eating bats, as well as an assessment of the long‐term impact on population dynamics and reproductive success of nesting birds sharing such roosting spaces. Greater noctules feed on birds, including Eurasian blue tits, with the presumed strategy being in‐flight capture, yet no direct observations confirming this holds true. We recorded the successful nesting of blue tits in a tree cavity shared with around 25 greater noctules and recorded no predatory interactions over the whole nesting period. Our observation supports the hypothesis that roosting bats are not perceived as a threat, indirectly endorsing the ‘aerial hawking’ predation theory.

Urbanisation exerts profound effects on biodiversity, driving species extinctions while promoting behavioural adaptations in generalist taxa. The European badger (Meles meles) exemplifies such adaptability, exploiting anthropogenic resources and modifying activity rhythms. This study assessed badger activity within the Varese province in northern Italy, comparing an urban park and a sub-urban landscape. From August 2023 to August 2024, camera traps recorded badgers and sympatric mesocarnivores, including red foxes (Vulpes vulpes), domestic cats (Felis catus), and beech martens (Martes foina). Despite high activity overlap between sites (∆ = 0.87), the Mardia–Watson–Wheeler test revealed significant differences. Urban badgers displayed heightened nocturnality relative to sub-urban individuals, consistent with comparisons to nearby protected natural areas. This pattern indicates anthropogenic disturbance as a driver of temporal adjustment. Urban badgers are active from 18:00 to 07:00, whereas sub-urban badgers are active from 17:00 to 08:00. The later onset and earlier termination of urban activity suggest behavioural avoidance of human presence. Red foxes exhibited even greater nocturnality in urban settings, while domestic cats were primarily crepuscular and less frequently detected, particularly in sub-urban areas. Results underline the ecological plasticity of badgers, highlighting their capacity to accommodate urban pressures and providing city administrations with information to improve park management planning.

Although many studies highlighted the potential of COVID-19 to reshape existing models of wildlife management, empirical research on this topic has been scarce, particularly in Europe. We investigated the potential of COVID-19 pandemic to accelerate the ongoing decline in an aging population of recreational hunters in Italy. Namely, we modelled spatiotemporal trends between 2011 and 2021 in the number of recreational hunters in 50 Italian provinces with a varying incidence of COVID-19, and temporally delayed waves of infection. Compared to projections from 2011–2019 data, we detected a lower number of hunters who enrolled for the hunting season, both in 2020 (14 provinces) and in 2021 (15 provinces). The provinces with the highest incidence of COVID-19 in the Lombardy and Emilia-Romagna regions were also those experiencing the most marked decrease in hunting participation. Our findings revealed that a wildlife management system based on recreational hunting can be rapidly destabilized by epidemics and their associated public health measures, particularly when the average age of hunters is high, like in Italy. Considered the high incidence attained by COVID-19 in many European countries, where hunters are pivotal for the management of large ungulates and where they were already declining before the pandemic, our findings call for further large-scale research about the impact of COVID-19 on hunting participation.

Wetlands are widely recognised as the most critical stop-over locations along migration flyways. Wetland ecology is mostly influenced by water levels and water regimes. This research focuses on Bolle di Magadino (Switzerland), an important stop-over site on Lake Maggiore, artificially regulated by a dam. In this work we examined how the artificial flooding of a wetland affects the use of this stop-over site by migrating passerines during spring. Bird presence in the area was evaluated using both data collected at the ringing station located in the wetlands and the bird traffic rate (BTR) supplied by the BirdScan MR1, an avian verticallooking radar (VLR) capable of automatically detecting and classifying birds in flight. In an attempt to shed light on the effect of lake level on stop-over quality, we i) simulated with GIS the extent of the flooded area and of the different habitat categories as the lake level changes; ii) calculated the relationship between lake level and the ability of stop-overing birds to acquire trophic resources; iii) verified that the flux of passerines below 500 m above ground level measured by radar could be used as a proxy for the number of stop-overing birds; iv) calculated the relationship between the number of birds leaving the stop-over and the lake level. While the number of ringed passerines has proven to be representative of the migratory flow below 500 meters of altitude at the site of interest, a high lake level seems to have a negative impact on the use by some species of the Bolle di Magadino area as a stop-over site during spring. In particular, two of the target species -the blackcap and the reed bunting- have proven to be sensitive to higher water levels. While taking into account the limitations and the relative nature of the results, could be necessary for the competent authorities to take these results into consideration in order to safeguard the Bolle di Magadino’s role as an important stop-over area during spring.

Climate change poses a significant threat to biodiversity, with extreme weather events such as heatwaves exacerbating the risks to animal populations. Temperature extremes can cause high physiological stress in animals, particularly in species or life stages with limited thermoregulatory abilities. While available evidence pertains to flying foxes and bats using bat boxes or dwelling in urban environments, heatwave‐induced mortality in forest‐dwelling species in temperate forests has not been reported. We present the first evidence of heatwave‐related mortality in temperate forest bats, specifically in common noctules Nyctalus noctula, observed in northeast Italy during the summers of 2023 and 2024. Our fieldwork, conducted in a forest fragment in the Friuli‐Venezia Giulia Region (Northeastern Italy), identified 17 dead juvenile bats found at the base of roost trees during periods of extreme heat (Tmax ≥ 30°C). Laboratory necropsies revealed that the cause of death was consistent with heat‐related stress, as no viral infections were detected, and recent feeding evidence was present in a few individuals. Dead bats are difficult to find in forests, especially when mortality occurs in unsurveyed areas, scavengers remove carcasses, or deaths go unnoticed within roost cavities. Consequently, our observations likely represent only a limited fraction of actual mortality. The phenomenon may be quantitatively significant and widespread. The findings highlight the vulnerability of bat populations to heatwaves, particularly in fragmented forest habitats where roosting opportunities are limited. Our results allow us to hypothesise that forest fragmentation increases exposure to heat stress, particularly along forest edges. In the context of climate change, roosts deemed suitable may act as ecological traps, making this a hypothesis worth testing. This is the first recorded case of forest bat mortality in temperate regions caused by heatwaves. The study suggests that forest fragmentation exposes bats to lethal thermal peaks, highlighting a previously overlooked impact of climate change on these mammals and potential interactions with forest fragmentation.

Animal size, a trait sensitive to spatial and temporal variables, is a key element in ecological and evolutionary dynamics. In the context of climate change, there is evidence that some bat species are increasing their body size via phenotypic responses to higher temperatures at maternity roosts. To test the generality of this response, we conducted a >20‐year study examining body size changes in 15 bat species in Italy, analysing data from 4393 individual bats captured since 1995. In addition to examining the temporal effect, we considered the potential influence of sexual dimorphism and, where relevant, included latitude and altitude as potential drivers of body size change. Contrary to initial predictions of a widespread increase in size, our findings challenge this assumption, revealing a nuanced interplay of factors contributing to the complexity of bat body size dynamics. Specifically, only three species (Myotis daubentonii, Nyctalus leisleri, and Pipistrellus pygmaeus) out of the 15 exhibited a discernible increase in body size over the studied period, prompting a reassessment of bats as reliable indicators of climate change based on alterations in body size. Our investigation into influencing factors highlighted the significance of temperature‐related variables, with latitude and altitude emerging as crucial drivers. In some cases, this mirrored patterns consistent with Bergmann's rule, revealing larger bats recorded at progressively higher latitudes (Plecotus auritus, Myotis mystacinus, and Miniopterus schreibersii) or altitudes (Pipistrellus kuhlii). We also observed a clear sexual dimorphism effect in most species, with females consistently larger than males. The observed increase in size over time in three species suggests the occurrence of phenotypic plasticity, raising questions about potential long‐term selective pressures on larger individuals. The unresolved question of whether temperature‐related changes in body size reflect microevolutionary processes or phenotypic plastic responses adds further complexity to our understanding of body size patterns in bats over time and space. This study spanning over 20 years and involving 15 bat species in Italy challenges the expectation of a widespread increase in body size in response to climate change. Contrary to predictions, only three out of the 15 species exhibited a noticeable size increase, prompting a revaluation of bats as reliable indicators of climate change based on body size alterations. We identify temperature‐related variables, sexual dimorphism, latitude, and altitude as crucial factors influencing bat body size dynamics, revealing a nuanced interplay that adds complexity to our understanding of how bats respond to environmental changes over time and space.

Mast seeding, the variable and intermittent production of seeds, has cascading effects on ecosystem functioning. This study explores its influence on the brown bear populations in the Italian Alps, focusing on beechnuts (Fagus sylvatica L.), the primary food source for bears in the region. Using historical data and field sampling, we estimated and mapped the annual seed biomass from 2007 to 2021 for the province of Trento. The energy content of beechnuts was assessed through high heating values, providing the caloric resources available. Data on beechnuts production, records of damages and GPS data from 16 Eurasian brown bears were integrated to perform a temporal and spatial analysis at home range and at landscape level. Standardised damages to beehives and livestock decreased during mast years, suggesting that bears met their trophic needs through natural food sources. In fact, bears used more agricultural areas and less beech forest during years of beech crop failure. At landscape level, agriculture and pasture areas close to beech forests and distant from cities showed a higher risk of damage, providing a tool to anticipate management actions. This work provides insights on the ecological dynamics and conservation implications of brown bears in the study area by mapping the spatial and temporal aspects of mast seeding and bear‐related damages. Using a 20‐year period of observations from different sources, this article examines the spatial and temporal patterns of beech masting in relation to brown bear movement and damage to livestock and human property. Standardised damages to beehive and livestock decreased during mast years, suggesting that bears met their trophic needs through natural food sources.

Nowadays, molecular techniques are widespread tools for the identification of biological entities. However, until very few years ago, their application to taxonomy provoked intense debates between traditional and molecular taxonomists. To prevent every kind of disagreement, it is essential to standardize taxonomic definitions. Along these lines, we introduced the concept of Integrated Operational Taxonomic Unit (IOTU). IOTUs come from the concept of Operational Taxonomic Unit (OTU) and paralleled the Molecular Operational Taxonomic Unit (MOTU). The latter is largely used as a standard in many molecular-based works (even if not always explicitly formalized). However, while MOTUs are assigned solely on molecular variation criteria, IOTUs are identified from patterns of molecular variation that are supported by at least one more taxonomic characteristic. We tested the use of IOTUs on the widest DNA barcoding dataset of Italian echolocating bats species ever assembled (i.e. 31 species, 209 samples). We identified 31 molecular entities, 26 of which corresponded to the morphologically assigned species, two MOTUs and three IOTUs. Interestingly, we found three IOTUs in Myotis nattereri, one of which is a newly described lineage found only in central and southern Italy. In addition, we found a level of molecular variability within four vespertilionid species deserving further analyses. According to our scheme two of them (i.e. M.bechsteinii and Plecotus auritus) should be ranked as unconfirmed candidate species (UCS). From a systematic point of view, IOTUs are more informative than the general concept of OTUs and the more recent MOTUs. According to information content, IOTUs are closer to species, although it is important to underline that IOTUs are not species. Overall, the use of a more precise panel of taxonomic entities increases the clarity in the systematic field and has the potential to fill the gaps between modern and traditional taxonomy.