Road ecology in a Neotropical biodiversity hotspot: monitoring effectiveness of wildlife crossings in the Atlantic Forest, Argentina

VARELA, DIEGO

Malmo

Congreso; IENE 2014 International Conference on Ecology and Transportation; 2014

IENE

In the last decades the increase of transport infrastructure in Latin America represents a serious threat to habitats and species in biodiversity hotspots. Nowadays, new roads break through protected areas and biological corridors, and old dirt roads are being paved, thus decreasing ecological connectivity and increasing wildlife road-kills. Road ecology is an emerging discipline in Latin America and there are only few known cases of mitigation measures designed to minimize the impact of roads on Neotropical wildlife. The subtropical forests of north-eastern Argentina (Misiones Province) are considered one of the major and best connected remnants of the whole Atlantic Forest eco-region, still maintaining viable populations of large mammals. However, paved roads are affecting threatened species as jaguars and tapirs. During the last years, the Road Administration of the Misiones Province showed an increasing commitment about wildlife issues undertaking the construction of the first wildlife passages (underpasses) of Argentina and the first wildlife overpass (ecoduct) of Latin America. The aim of this study was to evaluate how large- and medium-sized mammals use seven wildlife passages on two roads (RP-19 and RN-101) within and around Urugua-í Provincial Park (84,000 ha). The RP-19 cross through the park and have four small underpasses built 20 years ago, whereas RN-101 border the park and have two medium-sized underpasses and one wildlife overpass (40 m width) built in 2008.Wildlife passages were monitored by infrared camera traps (Reconyx RC60OH). One camera was placed inside each underpass while two camera traps were deployed in the overpass due to its larger surface. All cameras operated 24h per day. The overpass was monitored for three years (2011-2013) and underpasses for two years (2012-2013). The mean sampling effort dedicated to each passage was 168 days/year (range: 121-219 days/year). To ensure independence, consecutive photographs of the same species within one hour were excluded. Wildlife Crossing Use Index (WCUI) was defined as the ratio between independent crossing events and sampling effort (camera-days).Until now, 24 species of large- and medium-sized mammals were recorded in the seven wildlife crossings. This represents 83% of all species potentially present in the region. Tapirs, dwarf brockets, red brockets, collared peccaries, pacas, tayras, ocelots, and oncillas were recorded among others. The WCUI in the oldest underpasses of RP-19 were more than sevenfold greater that in RN-101. However, only the wildlife crossings of RN-101 showed an increase in WCUI and in the number of species recorded across years, revealing a process of progressive species adaptation to the structures after its construction. During 2013, some underpasses of RP-19 showed a decrease in WCUI possibly due to management problems, such as excessive water accumulation or anthropogenic disturbances (road maintenance works).These results indicate that wildlife crossings provide safe passage for Neotropical mammals on roads of Misiones. Nonetheless, species like jaguars, pumas, and white-lipped peccaries were not recorded using wildlife crossings yet. Long-term monitoring will allow a better understanding of species adaptation to these structures and will lead to better planning of mitigation measures for Latin American roads.