Diversidade, sazonalidade e a influência da paisagem no atropelamento de répteis na maior unidade de conservação do Bioma Pampa, Rio Grande do Sul, Brasil

Abstract

Highways are one of the major concerns of today as the conservation and biodiversity loss, generating ecological effects that disrupt ecosystem processes and the movement of wild animals. The Brazil presents 2,071 conservation units and few efforts have been made so far to assess the effects of roads on local wildlife. Road kill can be influenced by seasonal variations, and the magnitude of this variation depends on the taxon. The climate regime and the hit rates of reptiles are commonly higher in warmer seasons. The surrounding landscape on the highways is the most important factor in determining the direct impacts on wildlife and, in many ways, grassland ecosystems are still little known in various regions of the world. The present study aimed to determine the wealth, the frequency and the constancy of occurrence of Roadkill on the largest conservation unit (UC) of the Pampa biome in Brazil, the environmental protection area (APA) of Ibirapuitã. We test hypothesized that the road kill of reptiles are not evenly distributed throughout the year, as well as determine the influence of the landscape around highway (wet and dry field) on the patterns of richness and abundance of roadkill. The study was conducted in 26 km from BR-293 which crosses the southern part of the APA, located in the municipality of Santana do Livramento, Rio Grande do Sul. The monitoring was conducted twice a month, from October 2015 to October 2016. Totaling 1,352 km (roundtrip) cycling and walking, for an observer, in average speed of 15 km/h and 6 km/h, respectively. 426 reptiles were recorded hit, represented by 27 species in 9 families of two orders. The most abundant species were the snakes Philodryas patagoniensis, Erythrolamprus poecilogyrus and the lizard Salvator merianae. Of the species recorded, 59.25% accessory 22.22% were considered as occasional and 18.5% as constants. The rates removal of carcasses were found to be high, which seems to be related with the good condition of this unit, comprising high abundance of reptiles and scavenger animals. Both richness and abundance of roadkill presented significantly seasonal pattern, concentrated in the spring and summer period. The surrounding landscape in the monitored strech did not affect the species richness, but affected the pattern of abundance registered. Thus, stretch the influence of wet field snippets were segregated from excerpts under the influence of dry field, as well as presented a higher number of species considered native fields dependent. Mitigation strategies of the hit on the APA Ibirapuitã should be planned for the warm period of year (spring and summer) and must prioritize sections intersecting areas of wet grassland.