How many samples do you hope to collect on your next field assignment? 50, 100 or 1000? How about billions. It may seem overly optimistic, but that’s the reality when using Light Detection and Ranging, or LiDAR.
LiDAR works on the principle of firing hundreds of thousands of laser pulses a second that measure the distance to an intercepting surface. This harmless barrage of light creates a highly accurate 3D image of the target – whether it’s an elephant, a Cambodian temple or pedestrians walking down the street. LiDAR has made the news over recent years for its ability to unearth ancient temples through thick jungle, but for those of us with an ecological motive it is the otherwise impenetrable cloak of vegetation which is of more interest.
We wanted to test whether arboreal mammals were using natural canopy bridges – connections between tree branches over a clearing – to travel over a natural gas pipeline in the Peruvian Amazon. The challenge was figuring out how to monitor branches 100 feet up in the tree tops. In this case, the clearing was a 30-foot-wide pipeline path, and we expected arboreal mammals – like monkeys, squirrels and porcupines – to prefer crossing on the branches rather than on the ground. The ground is an unfamiliar and often dangerous place for an animal that’s spent its life way up in the canopy.
The yellow arrow shows the path captured by the camera trap.
In fact, we wondered if without branches, would arboreal mammals cross at all? How could we find out if animals were using the branches? There were 13 canopy bridges and finding a person to sit and wait all day (and night) under each of them for animals to cross wasn’t an option. With our goal of a year’s worth of monitoring, we had a conundrum. We needed a more efficient way to gather the data and concluded that camera traps – motion sensitive cameras – could be an excellent way to monitor the bridges continuously and remotely.
But, we discovered that no one had ever really used camera traps in the high canopy before. How were we going to get them all the way up there? If we were able to get up to the canopy, how could we make sure they were taking photos of the correct points where animals would potentially cross? Continue reading →