The importance of old secondary forests for understory birds in the tropical Andes

Deforestation is perhaps the greatest threat to tropical biodiversity. Anyway, extensive areas in the tropics have naturally regenerated and become secondary forests, which might mitigate biodiversity loss. However, evidence about the value of secondary forests for biodiversity conservation is still controversial. To establish the conservation value of secondary forests in the tropical Andes, we compared bird species richness, abundance, and composition between old and mature secondary forests using camera traps for two consecutive years. Our results suggest that old and mature secondary forests are similar in species richness and abundance to mature secondary forests, but these habitats significantly differ in species composition. Old secondary forests harbored some species highly specialized to mature forests (e.g., ant-following insectivorous birds: Myrmeciza longipes, Gymnopithys bicolor, Formicarius analis, and Dendrocincla fuliginosa) that are highly sensitive to habitat disturbance. Additionally, old secondary forests constitute suitable habitat for several species with decreasing populations, which could become of conservation importance in the long run. We consider that old secondary forests surrounded by mature forests can contribute to conserving understory birds, one of the most susceptible groups, negatively affected by tropical forest loss and degradation. Therefore, strategies for habitat biodiversity protection in this region should also include old secondary forests.