Movement responses to environment: fast inference of variation among southern elephant seals with a mixed effects model

• Published in: Ecology
• Main Authors: Jonsen, ID, McMahon, CR, Patterson, TA, Auger-Methe, M, Harcourt, R, Hindell, MA, Bestley, S
• Format: Article in Journal/Newspaper
• Language: English
• Published: Ecological Soc Amer 2019
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; Southern Ocean; The Antarctic; Antarc*; Elephant Seal; Elephant Seals; Mirounga leonina; Sea ice; Southern Elephant Seal; Southern Elephant Seals
• Online Access: https://doi.org/10.1002/ecy.2566; http://www.ncbi.nlm.nih.gov/pubmed/30467837; http://ecite.utas.edu.au/130085

Like many species, movement patterns of southern elephant seals ( Mirounga leonina ) are being influenced by long‐term environmental change. These seals migrate up to 4,000km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among individuals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast‐estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among‐individual variability in southern elephant seal environmentmovement relationships. We found that seals making foraging trips to the sea ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea‐ice coverage but had variable responses to chlorophyll a concentration, whereas seals foraging in the open ocean reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, open‐ocean foragers may encounter more productive habitat but sea‐ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat usage.