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.

Pest management requires the development of robust monitoring tools. In Italy, coypu Myocastor coypus (nutria) have been controlled since the early 1990s, but the effectiveness of these measures has never been tested. With the aim of developing a reliable and volunteer‐based method for the long‐term monitoring of coypu abundance in agricultural landscapes, we calibrated an index based on surveys for coypu paths against density estimates obtained through a standardized mark–recapture technique. Two trapping sessions were performed in winter for each of 12 1‐km long stretches of irrigation canals and watercourses using 15 baited cage traps. Trapping sessions lasted 7 days each, with a 10‐day break between sessions. Population size was assessed using three methods: Peterson–Lincoln's formula, capwire estimators and accumulation curves. Active coypu paths and five habitat variables were recorded by walking on the edge of both banks. The variables were then related to population size (y) by means of multi‐regressive models, testing for the predictive power of the selected models by leave‐one‐out cross‐validation. Multi‐regressive models included only the number of coypu paths with the best performances achieved by the model based on Peterson–Lincoln formula, supporting path count as an effective method to assess the abundance of the coypu in agricultural landscapes. Concurrently, to assess the field suitability of the indirect method, surveys for coypu paths were carried out on 122 randomly chosen 3‐km long stretches of irrigation canals and watercourses in the central part of the River Po valley (c. 15 000 km2; N Italy). The highest (>8/100 m) mean number of paths was recorded in the central part of the study area. According to the regression models, the overall number of coypu is predicted to range between 350 000 and 1 100 000, raising doubts about the effectiveness of current control measures.