Effects of fire regime on the bird community in an Amazonian savanna

Abstract

Savannas are ecosystems maintained by fires, characterized by a fire-adapted biota, and savanna patches occur in Amazonia in patches surrounded by tropical forest. Different fire regimes can generate structurally diverse vegetation, and savanna birds are known to be closely related to vegetation structure. However, long-term approaches and interaction of fire with other environmental factors need to be explored for the better understanding of the effects of habitat fire on birds. In an Amazonian landscape composed by savanna and forest, we investigate the effects of different fire regimes in a 12-ha area in three periods through 23 years. We also examined the effects of frequency and extent of fires, tree cover, and distance to forest on bird composition in twelve 3.7ha savannas plots. Birds were surveyed with mist-nets and species were classified as to their habitat use by comparison of registers in forest and savanna plots through visual/acoustical surveys. After 13 years of fire suppression, many forest species colonized the area and some savanna species were lost. Fire frequency and tree coverage affect avifauna communities. The avifauna was sensitive to the occurrence of fires, independent of fire extent. After one fire event in a plot that had been protected from fire for 12 years, some savanna species returned. These results highlight the effects of the fire regime on birds species composition and indicate that many savanna bird species depend on the occurrence of regular fires.