Nest site selection by a grassland-dependent Neotropical passerine, the Tawny-bellied Seedeater Sporophila hypoxantha

Abstract Increasing habitat loss and fragmentation along with other factors have led to the dramatic declines of multiple Sporophila seedeater species populations. However, the implementation of effective conservation measures is often hampered by the lack of knowledge about species’ ecological requirements in their breeding grounds. Here we evaluate vegetation structure and composition of Tawny-bellied Seedeater (Sporophila hypoxantha) breeding sites in the upland grasslands of southern Brazil. We compared vegetation variables of sites selected by nesting Tawny-bellied Seedeaters to those that were unoccupied (n = 130 plots in each group, encompassing 26 nests) using multivariate analyses and generalized linear models. Nesting sites had gentle slope, higher shrub cover, shrub height, and lower percent of bare ground in comparison to randomly sampled (unoccupied by nests) sites in the region. Also, selected nesting sites had a higher frequency of Andropogon lateralis, Saccharum angustifolium and Baccharis caprariifolia while unoccupied sites a higher frequency of Disynaphia multicrenulata, Escallonia megapotamica (small tree) and Eryngium horridum. Because Tawny-bellied Seedeaters breed mainly on dry grasslands rich in shrubs, with high density of grasses, management measures that favor this habitat structure as low-intensity grazing and moderate burning may benefit the reproduction of this species.