The location of pine marten records in northern Italy suggests that main rivers may play the role of natural corridors favouring this species’ colonisation of cultivated lowlands. We assessed the distribution and habitat use by the pine marten on a 35 km long stretch of the River Ticino. Surveys were carried out between October 2011 and June 2012 along linear transects in a 2 × 2 km grid. Using the variation in marking intensity as an indicator of habitat use, habitat selection was assessed at two landscape levels—at transect‐scale by the χ2 test with Bonferroni's confidence intervals for the proportion of use, and at grid‐scale by multiple linear regression. By a polymerase chain reaction–restriction fragment length polymorphism method, 91 faecal samples were assigned to the pine marten. Faeces were mainly located in wooded areas, while fields were avoided. At the grid‐scale of analysis, marking intensity was positively related to the mean area of wooded patches and negatively to their mean perimeter‐area ratio. This suggests that pine marten relative abundance may partially depend on the degree of fragmentation and structure of residual woods. The survey protocol allowed to assess the probability of detection. Occupancy models outlined that heterogeneity in detection probability may arise as a result of variation in marking intensity, i.e. the number of marking individuals. Our results suggest that the availability of both woodland corridors and wood patches are major factors shaping pine marten distribution in intensively cultivated plains and that non‐invasive genetic surveys are a cost‐effective method for future studies at a broader scale.

Invasive species are among the top five causes of biodiversity loss worldwide. Arundo donax has progressively colonized the riparian zones of Mediterranean rivers with detrimental effects on terrestrial and aquatic biodiversity, being catalogued as one of the 100 worst invasive species. In order to control this invasive species and restore native riparian vegetation, different methods have been traditionally used, depending on the environmental, economic and social context. Here, the effect of repeated above-ground removal of A. donax on aquatic and terrestrial communities was assessed by testing two different frequencies of mowing (monthly-intensive and quarterly-extensive), combined with the plantation of native species. Specifically, it was evaluated if riparian vegetation, birds and aquatic macroinvertebrates showed significant responses throughout time and between restoration treatments based on 4-year annual biomonitoring data (2015–2018). Changes in taxonomic diversity and ecological quality indices for the different biological communities were tested using mixed-effect models (LMEs). Similarly, comparisons between restored and reference sites were also performed. LMEs were also applied to assess how riparian variables were related to bird and aquatic macroinvertebrate indices. NMDS and MGLM-Mvabund analyses were performed to detect significant post-treatment differences in taxa composition compared to the initial state and reference sites. During this short-term assessment, increases in riparian and aquatic macroinvertebrate richness and quality indices were found, as well as significant decreases in A. donax height, density and cover, without significant differences between restoration treatments. However, differential effects between extensive (positive-neutral effect) and intensive treatments (neutral-negative effect) were detected for bird richness, density and abundance. After three years of restoration actions, restored sites are still far from reference values in terms of taxa composition, species richness and ecological quality, especially for riparian vegetation and birds. Given the high cost and the great efforts required for restoration, extensive repeated mowing, together with native species plantation, are only recommended on river reaches not fully invaded by A. donax and with a high ecological interest.

In the catchment of the River Segura (SE Spain), ongoing Eurasian otter (Lutra lutra) recovery and concurrent spread of human settlements are resulting in increasing otter records into urban areas. We analysed otter diet along a natural-to-urban gradient, with the main aim of assessing to which extent man-driven variation in food availability affects its feeding habits and how this secretive mustelid can thrive in apparently unsuitable habitats. From 2016 to 2019, we collected 521 spraints, monitoring 37 sampling stations (mean length ± SD = 0.5 ± 0.3 km). In natural areas, the percent cover of undisturbed banks was the highest, with the lowest number of water abstraction systems, whilst water pollution was the highest in urban areas. Introduced red swamp crayfish (Procambarus clarkii) and fish formed the bulk of otter diet. The two most preyed fish, Luciobarbus sclateri and Pseudochondrostoma polylepis, were among the most abundant species in the river, confirming the generalist feeding behaviour of the otter. The contribution of nonnative fish was on average low, while invasive crayfish exceeded the overall importance of fish in all habitats except urban areas. Overall, diet data did not allow attesting food as a limiting resource for otters in urban areas. In contrast, marking intensity varied consistently with the natural-to-urban gradient (from 0.31 to 0.65 spraints/100 m in urban-and natural areas, respectively), suggesting that human disturbance (i.e. habitat modification and water pollution) may play a major role in shaping otter distribution.

In semi-arid environments, the effects of irregularly distributed rainfall, flow regulation and water inter-basin transfer enhance the spread of non-native fish to the detriment of native communities. In the River Segura, since the 1980s the number of non-native fish species has progressively increased, also because of the building of water transfer facility connecting the rivers Segura and Tajo. With the aim of highlighting how man-driven changes in the diversity of fish communities affect the diet of top-predators, we compared Eurasian otter Lutra lutra diet in the span of 20 years, i.e. 1997–98 vs. 2016–19. As habitat quality affects the condition of Andalusian barbel Luciobarbus sclateri, the most widespread native fish, we also compared the size of preyed barbels to point out whether human activities may have lowered their profitability to otters. Fish and introduced red swamp crayfish Procambarus clarkii formed the bulk of otter diet in both study periods. In 2016–19 the contribution of non-native species to otter diet increased significantly, both for crayfish and fish, which included ten non-native species. Otter feeding habits faithfully mirrored the variation in the composition of the fish community and confirmed the importance of crayfish as alternative-to-fish prey in the Iberian Peninsula. The average length of preyed barbels was significantly lower in the second study period, consistently with a decline in barbel profitability for otters.

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