Factors afecting abundance of forest birds in cerrado biome

Local abundance patterns are recognized to exist within a species’ range (geographic distribution area). In order, to understand species abundance patterns is important to assess the relationship with climatic and habitat factors. Here we used GLMs with Poisson distribution to assess hypotheses related to bird species abundance across the geographic distribution – centroid-periphery and habitat suitability, and to forest cover (NDVI – Normalized Difference Vegetation Index) in a 1 km buffer around survey points. We expected to find a negative relationship between species abundance and the distance to the distribution centroid and a positive relationship with forest amount and forest cover. We estimate a suitability bioclimatic index in program MAXENT. We conducted point-counts (3-5) in 53 independent forest sites across the Cerrado central region and estimated abundance of 31 forest bird species. The mean relative abundance found to birds was 0.38 ± 0.01 EP. We found that abundance of 25 bird species had significant relationships with variables considered. Our results showed a significant positive relationship between habitat suitability and abundance of 21 species, as was expected. We found a significant relationship between NDVI and abundance just for 11 species. Contrary to our expectations this relationship was negative for 10 of the species. For distance to centroid variable we found a significant relationship only for six species. Contrary to our expectation the relationship was positive for three of them. Habitat suitability, more then distance to centroid of distribution, showed to be an important variable to predict forest bird abundance in our study area in Cerrado region.