Dear MARMAM colleagues, We are pleased to announce the publication of the following paper online: Theoni Photopoulou, Karine Heerah, Jennifer Pohle and Lars Boehme. 2020. Sex-specific variation in the use of vertical habitat by a resident Antarctic top predator. Proceedings of the Royal Society B: Biological Sciences 287(1937): 20201447 Abstract: Patterns of habitat use are commonly studied in horizontal space, but this does not capture the four-dimensional nature of ocean habitats (space, depth, and time). Deep-diving marine animals encounter varying oceanographic conditions, particularly at the poles, where there is strong seasonal variation in vertical ocean structuring. This dimension of space use is hidden if we only consider horizontal movement. To identify different diving behaviours and usage patterns of vertically distributed habitat, we use hidden Markov models fitted to telemetry data from an air-breathing top predator, the Weddell seal, in the Weddell Sea, Antarctica. We present evidence of overlapping use of high-density, continental shelf water masses by both sexes, as well as important differences in their preferences for oceanographic conditions. Males spend more time in the unique high-salinity shelf water masses found at depth, while females also venture off the continental shelf and visit warmer, shallower water masses. Both sexes exhibit a diurnal pattern in diving behaviour (deep in the day, shallow at night) that persists from austral autumn into winter. The differences in habitat use in this resident, sexually monomorphic Antarctic top predator suggest a different set of needs and constraints operating at the intraspecific level, not driven by body size. The paper is freely available here: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.1447 Please feel free to get in touch with any questions about our work. All the best, Theoni -- Theoni Photopoulou, Research Fellow Centre for Research into Ecological and Environmental Modelling School of Mathematics and Statistics University of St Andrews