Fire effects on the composition of a bird community in an amazonian Savanna (Brazil)

Abstract

The effects of fire on the composition of a bird community were investigated in an Amazonian savanna near Alter-do-Chão, Pará (Brazil). Mist-net captures and visual counts were used to assess species richness and bird abundance pre-and post-fire in an approximately 20 ha area. Visual counts along transects were used to survey birds in an approximately 2000 ha area in a nearby area. Results using the same method of ordination analysis (multidimensional scaling) showed significant effects of fire in the 20 ha and 2000 ha areas and strongly suggest direct effects on bird community composition. However, the effects were different at different spatial scales and/or in different years, indicating that the effects of fire vary spatially and/or temporally. Bird community composition pre-fire was significantly different from that found post-fire. Using multiple regression analysis it was found that the numbers of burned and unburned trees were not significantly related to either bird species richness or bird abundance. Two months after the fire, neither bird species richness nor bird abundance was significantly related to the number of flowering trees (Lafoensia pacari) or fruiting trees (Byrsonima crassifolia). Since fire is an annual event in Alter-doChão and is becoming frequent in the entire Amazon, bird community composition in affected areas could be constantly changing in time and space.Keywords: fire, savanna, Amazonia, birds, community. RESUMO Efeitos do fogo na composição da comunidade de aves em uma Savana amazônica brasileiraOs efeitos do fogo na composição da comunidade de aves foram estudados em uma savanna perto de Alterdo-Chão, Pará, Brasil. Capturas usando redes ornitológicas e contagens visuais foram usadas para amostrar a riqueza de espécies e abundância de aves antes e depois do fogo em uma área de aproximadamente 20 ha. Contagens visuais ao longo de transectos foram usadas para amostrar aves numa área vizinha de aproximadamente 2000 ha. Resultados usando os mesmos métodos de análise de ordenação (escalonamento multidimensional) mostraram efeitos significativos do fogo nas áreas de 20 ha e 2000 ha, e sugerem fortemente que houve efeitos diretos do fogo na composição da comunidade de aves. Entretanto, os efeitos foram diferentes nas diferentes escalas espacias e ou anos, indicando que os efeitos do fogo variam espacialmente e ou temporalmente. A composição da comunidade de aves antes do fogo foi significativamente diferente daquela depois do fogo. Análise de regressão múltipla indica que o número de árvores queimadas e não queimadas não foi significativamente relacionado à riqueza de espécies ou à abundância de aves. Dois meses depois do fogo, nem a riqueza de espécies nem a abundância de aves foram significativamente relacionadas ao número de árvores florindo (Lafoensia pacari) e árvores frutificando (Byrsonima crassifolia). Como o fogo é um evento anual em Alter-do-Chão, e está se tornando frequente na Amazônia, as comunidades de aves em áreas afetadas pelo fogo podem estar mudando constantem...

Spatial Variation in Bird Community Composition in Relation to Topographic Gradient and Forest Heterogeneity in a Central Amazonian Rainforest

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“…Although the mechanisms that determine habitat use in tropical forests remain poorly understood [3,4], it is clear that different species use their surrounding environment differently. This use can change over space and time due to individual movements, but also as a result of differences in habitat structure [5][6][7][8][9]. Several studies have focused on the factors affecting avian species richness and abundance in tropical forests, investigating the relationship between vegetation structure and bird communities [2,[8][9][10]], but few have investigated how natural variations in the structure of the forest may affect entire species assemblages (but see [4,7,11]).…”

Fire and Host Abundance as Determinants of the Distribution of Three Congener and Sympatric Mistletoes in an Amazonian Savanna

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The impacts of fire on birds in Australia's tropical savannas

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