Avifauna de los hábitats de la desembocadura del Río Atrato (Turbo, Antioquia)

Avifauna of the habitats at the mouth of the Atrato River (Turbo, Antioquia)

Abstract

We studied the spatial distribution of birds along the Atrato river mouth in association to the distribution of habitats available in the study area: Mangrove, Riverine vegetation, and Coastal flooded plains. To quantify whether changes in bird composition were related to changes in habitat we estimated beta diversity metrics within and between habitats and in relation to those expected under a null model. In a qualitative manner, we performed a Principal Component Analysis (PCA) to visualize the relationships among sites based on their species composition. Finally, we evaluated if a list of birds observed during a point count could be correctly assigned to a particular habitat using linear discriminant analysis with cross validation (LDA). We found that bird diversity and composition varied among habitats. Mangroves contained the lowest observed and estimated richness, the lowest diversity and the greatest dominance. On the other hand, Riverine vegetation had a greater observed and estimated richness, the largest diversity and lower dominance. The greatest observed and estimated richness was found in Coastal flooded plains. Beta diversity was larger between habitats than within habitats. Nonetheless, most pairwise comparisons among point counts were included in the expectations of the null model. Results from the PCA were consistent with results obtained from beta diversity indices; using the first two principal components (31% of the total variance), habitats can be differentiated based on their bird composition. LDA results showed a low precision in assigning point counts to a particular habitat. In summary, we conclude that the distribution of habitats plays a major role in determining the distribution of bird communities. Nevertheless, it is only possible to detect these differences using groups of point counts.