Evaluation of the use of highway bridges as wildlife crossings in the department of Rocha, Uruguay

Uruguay has a large number of watercourses, drains and bridges on national routes, which can represent a less expensive and more effective opportunity for wildlife crossings to reduce the trampling of wildlife. In this work, it was proposed to generate basic information and to know if medium and large wild mammals use the lower part of bridges to move. Using GIS and a subsequent diagnosis in the field, five bridges were selected in regions of high mortality due to run over, located on two national routes (routes 9 and 15). 1 or 2 camera-traps programmed to take three photographs and one video were placed. From May 2020 to date, nine species of mammals have been recorded. When compared with the database of accidents generated since 2015 in the area, the results show that the mammalian species that use the lower part of the bridges may not have a record of accidents in the area or its surroundings, such as the capybara. Hydrochoerus hydrochaeris and the margay Leopardus wiedii (an internationally threatened species and a priority for conservation at the national level), may have a very low rate of hit-and-run records, such as the guazubirá Mazama gouazoubira, or have a high run-over rate such as the bare hand Procyon cancrivorus, mountain fox Cerdocyon thousand, gray fox Lycalopex gymnocercus and skunk Conepatus chinga. This could be associated with the relative abundance of these species or it could be indicating that bridges alone are not the only measure necessary to reduce collisions. The information derived from this project will allow progress in mitigation and adaptation measures for bridges to reduce abuses in conjunction with the Ministry of Transportation. Subsidized by: 32885-B The Rufford Foundation