Between 2016 and 2019 the impacts caused by Federal Highway 2, section Ímuris – Sonora-Chihuahua State Limits,on the Sonoran wildlife were monitored. This highway is one of the main barriers for ecological connectivity in the Sky Islands, a region considered of high biological diversity because of the convergence of the Sonoran Desert, the Chihuahuan Desert, the Western Sierra Madre and the Rocky Mountains. This road specifically affects diverse species and fragments the habitat of threatened or endangered mammals (NOM-059 SEMARNAT 2019) that have a wide range of distribution such as black bear (Ursus americanus), ocelot (Leopardus pardalis) and jaguar (Panthera onca).
In 2016, 2018 and January 2019, we carried out sampling efforts every two weeks to document wildlife roadkill, registering a total of 330 individuals of 43 species, seven of them listed in some category of protection. The most frequently registered species were coyote (Canis latrans), Mephitis skunks, gray fox (Urocyon cinereoargenteus), Sylvilagus rabbits, Lepus hares and coachwhip snake (Masticophis flagellum). In addition to the regular monitoring, we registered a female black bear roadkill in September 2018, 25 km northeast of Ímuris, Sonora.
We subsequently analyzed the data and identified 27 critical sites along the Ímuris – Sonora-Chihuahua State Limits section (Sky Islands stretch), of which 14 are located in the Sierra Azul-El Pinito wildlife corridor and the Cocóspera River valley, six in the grasslands between the cities of Cananea and Agua Prieta and the remaining seven in the Sierra Peloncillo wildlife corridor.
In 2017, we registered 707 highway drainages and bridges which we classified by type, size and potential use by wildlife. In 2018, we placed a total of 24 camera traps in a selection of these drainages in two wildlife corridors: Sierra Azul-El Pinito, located approximately 20 kms northeast of Ímuris near the Area Designated Voluntarily for Conservation (ADVC) Rancho El Aribabi, and Sierra Peloncillo, located60 km east of Agua Prieta, dividing the ADVC Los Ojos. To date, our cameras have registered 18 species using drainages to cross the road including cougars (Puma concolor) and several small and medium mammals.
To reduce wildlife roadkill and restore habitat connectivity, we recommend the construction of wildlife crossings, inductive fencing, construction of escape ramps and clearing of drainages. Our studies allow us to determine the most suitable areas to establish these mitigation measures in order to reduce the impact of this road on the regional wildlife.