Unmanned Aerial Systems (UAS), sometimes called drones, offer enormous potential as research tools for conservation scientists. These small aircraft are rapidly increasing in technological sophistication and endurance, and can be used to collect data on wildlife and their habitats without disturbing either.
San Diego Zoo Global maintains its leadership role in conservation by applying the latest technological advances to solving the world’s most pressing conservation challenges, such as decreasing Arctic sea ice that is impacting polar bears’ survival. Recognizing the opportunities that UAS offers for enhancing our conservation efforts, scientists from the San Diego Zoo Institute for Conservation Research recently teamed up with engineers and programmers from Northrop Grumman Corporation to develop and deploy a UAS for our research.
The team from Northrop Grumman custom-built a UAS that was designed and rigorously tested to withstand the extreme conditions of our global field sites. This large, multirotor electric UAS is held aloft like a helicopter and kept stable—even in strong winds—by six propellers, and it can fly for up to 25 minutes at a time. The UAS has a unique sensor pod attached to its underside that contains an integrated suite of powerful sensors and cameras, including a 51-megapixel visual camera, a gimbal-mounted video camera, a multispectral sensor that can scan landscapes in different light wavelengths, a thermal infrared sensor that can generate heat maps of the landscape, and a 3-D radar sensor.
The data collected by the sensor pod is extremely accurate, because the UAS matches it to five onboard GPS receivers, as well as location data collected by an external Real Time Kinematic (RTK) base station GPS. The UAS is also highly intelligent—we simply preprogram the area we want to survey, and its software will automatically calculate the transects it needs to fly along to collect the imagery and data we seek. Consequently, we are able to collect detailed and accurate information across broad swaths of habitat in near real-time, and in a rapid and highly cost-effective manner.
Our initial field deployment of the UAS was to the frozen landscapes of the Canadian Arctic, to survey and map the sea ice that comprises critical habitat for polar bears. It is this sea ice that enables polar bears to hunt seals, which make up the bulk of their key food resources. If the sea ice does not form, polar bears struggle to meet their nutritional demands—and this can dramatically impact polar bear survivability and breeding success. Our combined San Diego Zoo Global and Northrop Grumman team assembled at a remote field cabin near Churchill, Manitoba, to deploy the UAS and survey the sea ice forming across the shores of Hudson Bay, a major hotspot of polar bear activity.
Our team was delighted with the performance of the UAS, and the quality and quantity of the remote sensing data it collected. We successfully flew the UAS in multiple missions across the sea ice in temperatures as low as -30°C (-20°F) and it flew steadily in wind speeds of up to 32 kilometers per hour (20 miles per hour). The sensors in the UAS pod collected an amazing 2 gigabytes worth of data for every minute of flight time as it surveyed the landscape. From an altitude of 70 meters up (230 feet), it was able to acquire imagery at an incredible resolution of 6.5mm (0.26 inch), which was spatially corrected to just 4 cm (1.6 inches) geographic accuracy.
We used specialized software to stitch the individual sensor images into 3-D composite mosaics that provide accurate and informative visual representations of the landscape. For example, one of the tests of the UAS was to determine its ability to detect sites where polar bears have successfully hunted seals out on the ice, so we can build a spatial picture of hunting frequency. We set up simulated seal hunt sites, using red food coloring to represent seal blood across the areas that we surveyed. The high resolution of the imagery collected by the UAS made for easy detection of seal hunt sites against the background of the snow and ice.
We are excited to deploy the UAS in follow-up expeditions to the Arctic, to map changes in the sea ice and use the resulting data to inform and enhance strategies for polar bear conservation management. In the future, we hope to deploy the UAS in a range of different habitats, such as tropical rain forest, coastal, and savanna ecosystems. These future missions will bring exciting new scientific and engineering challenges and opportunities.
James Sheppard, Ph.D., is a scientist in Recovery Ecology at the San Diego Zoo Institute for Conservation Research. Read his previous post, An Eye in the Sky for Polar Bear Conservation.