Scientists in Antarctica recently tested a novel technique to measure the body size and mass of wildlife — aerial photography. The method, used on leopard seals (Hydrurga leptonyx), allows scientists to take necessary measurements of individual animals from aerial photos without spending the substantial time, labor and resources needed to physically capture them. It also avoids the stress that capture could cause the animals. Leopard seals hauled out in the Antarctic. Scientists took aerial photos of seals when they were on land. Photo credit: NOAA AERD The study, “An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system,” took place in Cape Shirref, Livingstone Island, Antarctica. Leopard seals are seasonally resident and already marked in this area. Historically, scientists have measured seals by darting the animal with a sedative, and maintaining sedation intravenously, Krause said. Once scientists sedated the animal, they would sample it, take all necessary measurements, reverse the sedative and release it, and then monitor it to ensure it recovered fully. The team tested the feasibility of aerial photography analysis to replace manual techniques. They went through several steps to ensure the best results, including taking photos of each animal immediately after capture from an unmanned aerial system (UAS), from four different altitudes for comparison. The UAS included a camera mounted on a small drone. Identifying information was removed from the test photos to avoid bias. Three independent observers also measured the animal’s length and width at standard…
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South Africa Today – Environment
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