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

Abstract

Savanna ecosystems are maintained by fires with a fire-adapted biota, and savannas occur in Amazonia in patches surrounded by tropical forest. Different fire regimes can generate structurally diverse vegetation, and the composition of savanna bird assemblages is 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 fire on birds. In an Amazonian landscape composed by savanna and forest, we investigated 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 3.7- ha savanna 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 without fire, many forest species colonized the area and some savanna species were lost. Fire regime affected avifauna assemblages. The avifauna was sensitive to the occurrence of fires. After one fire event in a plot that had not burned for 12 years, some savanna species returned. These results highlight the effects of the fire regime on birds and indicate that many savanna bird species depend on the occurrence of regular fires.