Home range, population density, and foraging behaviour of the Yellow-breasted Warbling-Antbird (Hypocnemis subflava) in forest fragments in southwestern Brazilian Amazonia

Hypocnemis subflava is endemic to southwestern Amazonia, where it prefers habitats dominated by bamboo. We estimated the home range size and population density of this species, and described its foraging behaviour and occurrence in bamboo. We collected data within 1 – ha plots located in three different 16-ha grids. The mean home range of the species was 0.65 ± 0.26 ha (mean ± SE). The population density was 0.44–0.75 individuals per hectare and 0.22–0.37 pairs per hectare within the different study plots. The birds foraged primarily in bamboo leaves (65%), using ‘reach’ and ‘sally’ movements, and foraging was most frequent at a height of 1.1–2 m. Logistic regression analysis indicated that the probability of occurrence of the species increases with the density of culms and percentage bamboo cover per ha. The home range of H. subflava is one of the smallest yet reported for a thamnophilid species, while the density of the bamboo-dwelling populations among the highest recorded for any Amazonian thamnophilid, including other bamboo forest specialists. The high degree of habitat specificity of H. subflava for bamboo-dominated environments makes the species vulnerable to the loss of its preferred habitat in the region.