An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system

• DOI: 10.1371/journal.pone.0187465
• Publication Date: 2017-11-29T18:23:32Z
• Authors: Douglas J. Krause; Jefferson T. Hinke; Wayne L. Perryman; Michael E. Goebel; Donald J. LeRoi
• Keywords: Footprint; Allometry; Tree Allometry; Aerial Survey

Measurements of body size and mass are fundamental to pinniped population management research. Manual measurements tend be accurate but invasive logistically challenging obtain. Ground-based photogrammetric techniques less invasive, inherent limitations make them impractical for many field applications. The recent proliferation unmanned aerial systems (UAS) in wildlife monitoring has provided a promising new platform the photogrammetry free-ranging pinnipeds. Leopard seals (Hydrurga leptonyx) an apex predator coastal Antarctica whose condition could valuable indicator ecosystem health. We aerially surveyed leopard known test precision accuracy from small UAS. Flights were conducted January February 2013 2014 50 samples obtained 15 unrestrained seals. UAS-derived standard length within 2.01 ± 1.06%, paired comparisons with ground statistically indistinguishable. An allometric linear mixed effects model predicted seal 19.40 kg (4.4% error 440 seal). Photogrammetric single, vertical image using UAS provide noninvasive approach estimating pinnipeds that may widely applicable.