Installation and monitoring of a canopy bridge connecting Atlantic Forest fragments containing endangered species in Northeastern Brazil

Abstract

In 2019, a canopy bridge was built connecting two fragments of the Atlantic Forest separated by the Pacatuba unpaved road within the Pacatuba-Gargaú Corridor. This bridge was built as part of the Brazilian National Action Plan for the Conservation of Northeastern Primates (Plano de Ação Nacional para Conservação dos Primatas do Nordeste – PAN PRINE). The forest fragments contain a variety of mammal species, including the endangered primate species Alouatta belzebul and Sapajus flavius. Between September 2019 and March 2020, we monitored the canopy bridge continuously with a Bushnell camera trap; for a total of 204 days of sampling, resulting in evidence of 113 independent passage events. During the monitoring period, four mammal species used the canopy bridge, the Endangered Sapajus flavius (blond capuchin monkey), Callithrix jacchus (common marmoset), Marmosa demerarae (woolly mouse opossum), and Marmosa murina (murine mouse opossum). The common marmoset (Callithrix jacchus) used the bridge most frequently, representing 50.44% of the passage events (57), while the blond capuchin monkey (S. flavius) crossed the bridge in 30 events (26.5% of total crossings). All other mammals used the bridge less frequently than the primates (23% of crossings were of opossums). There was no record of crossings by the red-handed howler monkey (Alouatta belzebul) during the monitoring period. The construction of the canopy bridge within the Pacatuba-Gargaú forest corridor promoted structural and functional connectivity of the forest habitats, affecting the movement of the Endangered blond capuchin monkey and the common marmoset and benefiting other arboreal mammal species. The results indicate that monitoring the use of this canopy bridge provided important insights into the behaviour and ecology of the species studied (e.g., activity patterns, social interactions, group sizes, and reproduction, among many others). In addition, the use of the bridge decreases the risks of animal-vehicle collisions and electrocutions. Considering our results, we strongly recommend constructing and implementing canopy bridges as a strategy for the conservation of arboreal species living in fragmented forest areas.