Pipeline Canopy Bridges for Golden Lion Tamarins — Projeto Connect, São João River Basin (Brazil)

Gas and oil pipelines operated by Petrobras/Transpetro cross the Environmental Protection Area of the Sao Joao River Basin/Golden Lion Tamarin (APA-BRSJ) in Rio de Janeiro state, a stronghold for the endangered golden lion tamarin (Leontopithecus rosalia). Because forest cannot be allowed to grow directly over pipelines for safety reasons, the resulting 25-30 m cleared right-of-way strips act as barriers for tamarins, marmosets and other canopy-dependent species, fragmenting their habitat.

Under Projeto Connect -- run by the Universidade Estadual do Norte Fluminense (UENF) with Associacao Mico-Leao-Dourado and Petrobras funding -- researchers installed simple canopy bridges spanning the cleared strip and monitored them with camera traps from September 2019 to April 2020, later adding forest-based control bridges for comparison (July-November 2020).

Of 1,917 total crossing events recorded, researchers analysed 356 in detail, finding 455 pipeline-bridge crossings by common marmosets and 257 by golden lion tamarins. Both species crossed pipeline bridges significantly faster and with more vigilance behaviour than on matched forest-canopy control bridges, evidence that the bridges function but that animals still perceive the open right-of-way as a higher-predation-risk environment.

The evidence is genuinely mixed: this specific canopy-bridge design achieved real, quantified crossings by the target species, but the Associacao Mico-Leao-Dourado's own project reporting notes that other passage types installed under the same broader programme have so far been used mainly by foxes, seriemas and anteaters, with tamarins and radio-collared sloths not yet recorded using those particular structures -- a reminder that passage design details matter and that not every crossing type succeeds equally.