Birds as ecological indicators of successional stages in a secondary forest, Antioquia, Colombia
The areas that recover from the disturbance after agriculture and livestock activities, generate an increase in secondary forests causing changes in the quantity and quality of the habitat available for birds. The Index of Biotic Integrity (IBI) compares the structure, composition and function of the assembly of birds in a secondary regeneration of the forest, from early to mature ages, to evaluate the ecological condition. The ecological integrity using the IBI, in four stages of secondary forest succession were studied. The IBI was developed using bird assemblages found in these four stages of forest succession, and its performance was compared with the general richness and Shannon’s diversity index. Five field samplings were carried out between June 2016 and February 2017, in which birds were recorded using fixed-radius point counts. Bird species were identified and their habitat of occurrence, foraging guild and potential indicators groups, were established. The species richness and Punctual Abundance Index (PAI) of all categories, obtained from each point count were used as candidate metrics. In total 9516 individuals, from 187 bird species, belonging to 42 families and 15 orders were registered and 34 different bird candidate metrics were defined to be tested against the four stages of forest succession. Thirteen of them were considered valid: richness of Insectivorous of forest interior species; abundance of exclusively forest species; abundance of open areas species; abundance of forest interior and edge species; abundance of open areas and edge species; abundance of Frugivorous guild; abundance of Granivorous guild; abundance of Omnivorous guild; abundance of Insectivorous guild; abundance of Scavengers guild; abundance of endemics species; abundance of threatened species, and abundance of migratories species. Each metric provided information about every one stages of secondary forest succession ecological integrity. The resulting IBI showed a positive significant linear relationship with the gradient of secondary regeneration of the forest, from early to mature ages, while Shannon´s diversity index and total species richness showed a negative significant linear relationship. The IBI proved better for assessing and interpreting ecological and environmental condition of stages of secondary forest succession.