Birds as ecological indicators of successional stages in a secondary forest, Antioquia, Colombia

Recovering areas from disturbance, after agriculture and livestock activities, increases secondary forests extension, which might change the quantity and quality of available habitat for birds. The Index of Biotic Integrity (IBI) compare the structure, composition and function of bird assemblages in secondary regeneration forest, from early succession to mature forest, to evaluate the ecological condition. Thus, the ecological condition along four stages of secondary forest in Antioquia, Colombia were studied using the IBI. This index was compared with richness and Shannon's diversity Index of the same bird assemblages. Five field surveys were conducted between June 2016 and February 2017, using fixed-radius point counts. In total 9 516 individuals, from 187 bird species, belonging to 42 families and 15 orders were recorded. Habitat of occurrence, foraging guild and potential indicators groups were established for every species. Species richness and Punctual Abundance Index (PAI) of all categories were defined as candidate metrics, and after evaluating a total of 34 metrics, 13 were selected for further analysis. Metrics that were positively correlated with successional forest gradient, from highest to lowest disturbance, were: species richness of forest interior insectivorous, abundance of exclusively forest species, abundance of forest interior and edge species, abundance of endemic species and abundance of threatened species. Metrics that were negatively correlated with successional forest gradient, from highest to lowest disturbance, were: abundance of species from open areas, abundance of open areas and edge species, abundance of frugivorous, abundance of granivorous, abundance of omnivorous, abundance of insectivorous, abundance of scavengers and abundance of migratory species. IBI showed a positive significant linear correlation with the gradient of secondary forest regeneration, from early to mature forest, while Shannon's diversity Index and species richness showed a negative significant linear correlation. So that, in this particular case, IBI proved to be better indicator that the classical measures for assessing and interpreting ecological and environmental condition along the secondary forest succession evaluated.