Stable isotope analysis of slow-growing, metabolically inert tissues is a common method for investigating foraging ecology in migratory animals, as direct observations of feeding are often not possible. Using tissue growth dynamics to interpret foraging timelines can maximize the utility of foraging data; however, applying inappropriate growth models is problematic, and high-resolution growth measurements are seldom made. We used photogrammetry to repeatedly measure the length of whiskers in 93 follicles over 670 d in a trained, captive northern elephant seal Mirounga angustirostris. We developed and optimized a follicle-specific growth model to describe the 18 000 whisker length measurements. Whiskers from the captive seal exhibited asymptotic growth that was described by the von Bertalanffy growth function. Applying the growth model to serially sampled whiskers from 4 free-ranging adult female northern elephant seals resulted in alignment of peaks in δ 15 N along the length of whiskers with the breeding haulout period, when seals are not feeding. Our study provides a high-resolution whisker growth model and is the first to use whisker growth dynamics to improve temporal interpretation of isotopic ratios.

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Date Presented 4/20/2018 The study showed that it is important for occupational therapy practitioners to address sensory needs in developing sleep education and consultation for community-dwelling older adults. Primary Author and Speaker: Megan Chang Additional Authors and Speakers: Megan Sadou, Stephanie Loh, Sarah Mcdonald, Barbara Moran, Diana Nguy