Evaluating the effectiveness of footprint platforms to detect invasive mammals: coypu (Myocastor coypus) as a case study

Abstract

Effective and easy-to-apply monitoring techniques are necessary to detect alien species at their first stage of invasion, allowing rapid removal or delimitation of the invaded range for eradication or control actions. Monitoring tools should be effective in detecting the target species, reduce false absences and allow an early detection. The coypu (Myocastor coypus) is a large semi-aquatic rodent native to subtropical and temperate South America, introduced all over the world for its valuable fur. We tested tracking plates in the framework of a coypu occupancy study to take into account false absences and define a standardized monitoring protocol for the species with a limited engagement of staff. We set 60 linear transects, each with 3 tracking plates, along artificial water bodies within the rice district in northwestern Italy and checked them for six consecutive days. For the analyses, we fitted single-season occupancy models to our detection history data. We detected coypu presence at least once in 29 out of the 60 investigated transects (48%). When modeling occupancy and detection probability constant in time and space, the estimate Ψ was 0.48 and detection probability p was 0.60. A minimum of four consecutive visits to the transects provided reliable detection. Coypu’s probability of presence was significantly driven by the amount of surface covered by rice plantations around the investigated water courses. The proposed method may function as a tool for the rapid detection of coypu on large-scale monitoring projects and in case of new colonization, and as a basis for subsequent prompt control actions.