Collaborative Research: Hunting in Darkness: Behavioral and Energetic Strategies of Weddell Seals in Winter

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AbstractIntellectual Merit: Weddell seals (Leptonychotes weddellii) locate and capture sparsely distributed and mobile prey under shore-fast ice throughout the year, including the austral winter when ambient light levels are very low and access to breathing holes is highly limited. This is one of the most challenging environments occupied by an aquatic mammalian predator, and it presents unique opportunities to test hypotheses concerning: 1) behavioral strategies and energetic costs for foraging and 2) sensory modalities used for prey capture under sea ice. To accomplish these objectives, we will attach digital video and data recorders to the backs of free-ranging Weddell seals during the autumn, winter and early spring. These instruments simultaneously record video of prey pursuit and capture and three-dimensional movements, swimming performance, ambient light level and other environmental variables. Energetic costs for entire dives and portions of dives will be estimated from stroking effort and our published relationship between swimming performance and energetics for Weddell seals. The energetic cost of different dive types will be evaluated for strategies that maximize foraging efficiency, range (distance traveled), and duration of submergence. The proposed study will provide a more thorough understanding of the role of vision and changing light conditions in foraging behavior, sensory ecology, energetics and habitat use of Weddell seals and the distribution of encountered prey. It also will provide new insights into survival strategies that allow Weddell seals to inhabit the Antarctic coastal marine ecosystem throughout the year. Broader Impacts: The proposed study will train two graduate students and a Post-doctoral Fellow. Outreach activities will include interviews, written material and photographs provided to print and electronic media, project web sites, high school email exchanges from McMurdo Station, hosting visiting artists at our field camp, and public lectures. We will provide a weekly summary of our research findings to teachers and students in elementary school programs through our websites, one of which received an educational award. Our previous projects have attracted an extraordinary amount of press coverage that effectively brings scientific research to the public. This coverage and the video images generated by our work excite the imagination and help instill an interest in science and wildlife conservation in children and adults.