Conspicuous roadside avifauna's seasonal variation in ecotone and wetland environments within the pantanal's Aquidauana Region

Abstract

Transport by road is the main mechanism for integrating Brazil, but roads are drivers of land cover conversion, fragmentation, and direct mortality by wildlife-vehicle collisions. In Aquidauana, BR419 and MS170 are important unpaved roads into the rural Pantanal region, and improvement and paving has been planned for BR419, which may increase risks to local avifauna. The aim of this study was to assess the species composition and richness of conspicuous avifauna (defined as being easily quantifiable using roadside surveys), and their spatial and seasonal variation among two important roadways. One of the surveyed roadways accessing rural areas of the Aquidauana region of the Pantanal was scheduled for improvement and paving. Transects of 73 km long were sampled along both highways, six samples along each transect between February and May 2012, for a full sample effort of 103:06 hours. A total of 6888 individuals from 33 families and 93 species were observed in the transects combined, and 83 species were identified in each transect. Jaccard Similarity Index was 0.79, and we found a statistically significant difference (P < 0.05) among the bird communities between the highways. Species associated with freshwater environments were more abundant along and indicator species of MS170. That avifauna along MS170 varied temporally and species richness was strongly correlated with river discharge, while the same was not true with BR419. Species particularly vulnerable to wildlife-vehicle collisions, e.g., vultures (Coragyps atratus, C. aura) and Southern Caracara (Caracara plancus), were abundant along BR419. While mitigation measures for mammals, reptiles, and amphibians are common and effective, the vertical movement of most birds into the roadway presents a different challenge for which a technical solution may not currently exist. To protect species observed along the currently unpaved roadways of Pantanal's Aquidauana region, following road improvement, speed limits should be calibrated to facilitate safe transportation for drivers and the continued existence of wild species.