Leopard seals in focus: new perspective on the foraging ecology of an apex predator

 

Douglas Krause, Ph.D. NOAA/AERD

 

Describing the foraging dynamics and tracking the body condition of apex predators is crucial to understanding ecosystem function and to effective conservation and management. Leopard seals are conspicuous apex predators in Antarctic coastal ecosystems; however, their foraging ecology is poorly understood. We implemented an integrated sampling design including ground and aerial morphometrics, biological samples, and bio-logger deployments in January and February between 2008 and 2014. While they are typically described as generalist apex predators, video, dive, and movement data suggest that individual seals employ specialized foraging patterns. They affect coastal ecosystems through pathways beyond direct predation, including intraspecific kleptoparasitism, predator-induced stress effects, facultative scavenging and food caching. Finally, photogrammetric measurements from a single, vertical image obtained using an unmanned aerial system (UAS) were as accurate as ground measures, and provide a noninvasive approach for estimating the mass and body condition of leopard seals that may be applicable to other pinnipeds.