Birds around the road: Effects of a road on a savannah bird community in southern Brazil

Abstract

Birds are highly susceptible to habitat fragmentation, traffic noise, roadkills, and other disturbances generated by the presence of roads. These impacts are manifested in the structure of bird communities and are mainly noticed near road edges. The main goal of this study was to evaluate the effects of a road on a savannah bird community in southern Brazil. The study was carried out within the Espinilho State Park (ESP), Rio Grande do Sul state. The ESP is divided by a road and we quantified bird abundance and richness along three transects, parallel to the road at different distances from it (T1: 10 m, T2: 250 m, T3: 500 m). To estimate bird richness and abundance we sampled five point counts along each transect. Sampling took place throughout the month of January 2015, during the summer. Bird species were categorized according to their feeding habits and habitat use. Richness and abundance increased with greater distance from the road. Transects closer to the roads were less similar than those more distant from the road. Insectivore species and species that use grassland and Espinilho habitat were less common in transects nearest the road. Our data indicate that road edges alter the species composition and structure of the bird community in the ESP, although our limited temporal sampling means that our results should be treated as preliminary. This effect is due to some species being attracted by the road whereas others avoid it or decline. Based on our findings, we reinforce the recommendation that roads should be avoided near or within areas destined for conservation. If roads must be built within or around protected areas, studies on the impact of these roads and possible mitigation measures are essential and urgent.