In the Peruvian Amazon, Gregory tests strategies that can help protect wildlife impacted by pipelines and other major projects. Her research focuses on animals that live almost exclusively in treetops, such as monkeys, kinkajous and opossums. Few people get to experience the tropical forest canopy firsthand. “It’s so multidimensional. There’s life springing out of every tree hole and every leaf,” says Gregory.
Species that occupy this part of the forest rarely visit the ground. Instead, they rely on connecting branches to navigate from tree to tree. These treetop pathways can be knocked down when trees are cleared for roads and pipelines. When they disappear, animals that live in the canopy lose access to parts of their territories.
“Animals know the areas they live in really well,” Gregory explains, “It’s like how we know where the grocery store is, where the drug store is, where we go to work.” Some monkey species, for example, revisit the same fruiting trees year after year to feed. When an animal gets cut off from its usual food source, it has to search for another. That takes time and energy, and it can lead to conflict among groups that must resort to competing for resources in a smaller area. Animals can also lose access to rare resources, such as salt and clay licks where they get minerals, trees where they sleep, and even potential mates.
But what if some of the treetop pathways that cross over pipeline clearings could be left intact, forming what Gregory calls “natural bridges”? With an altered landscape and fewer branches, would animals still use the bridges? Determined to find out, Gregory got to work on a new strategy of observing species that rarely step foot on the ground.
Repurposing the Camera Trap
She first considered tracking individual monkeys using radio collars to see if they would use the bridges, but ultimately ruled that out. Using radio collars to track animals is a common practice, but catching and collaring monkeys would not be easy. Researchers would first need to locate the monkeys in the canopy and then dart them to safely attach the collars. If that was successful, the data would still only reveal the use of the bridges by those few monkeys. Gregory wanted a full picture of how many different animals would use them to cross a pipeline clearing.