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The extent of increasing anthropogenic impacts on large marine vertebrates partly depends on the animals' movement patterns. Effective conservation requires identification of the key drivers of movement including intrinsic properties and extrinsic constraints associated with the dynamic nature of the environments the animals inhabit. However, the relative importance of intrinsic versus extrinsic factors remains elusive. We analyze a global dataset of ∼2.8 million locations from <2, 600 tracked individuals across 50 marine vertebrates evolutionarily separated by millions of years and using different locomotion modes (fly, swim, walk/paddle). Strikingly, movement patterns show a remarkable convergence, being strongly conserved across species and independent of body length and mass, despite these traits ranging over 10 orders of magnitude among the species studied. This represents a fundamental difference between marine and terrestrial vertebrates not previously identified, likely linked to the reduced costs of locomotion in water. Movement patterns were primarily explained by the interaction between species-specific traits and the habitat(s) they move through, resulting in complex movement patternswhenmoving close to coasts compared with more predictable patterns when moving in open oceans. This distinct difference may be associated with greater complexity within coastal microhabitats, highlighting a critical role of preferred habitat in shaping marine vertebrate global movements. Efforts to develop understanding of the characteristics of vertebrate movement should consider the habitat(s) through which they move to identify how movement patterns will alter with forecasted severe ocean changes, such as reduced Arctic sea ice cover, sea level rise, and declining oxygen content.

Addressing the potential changes in species distribution in response to global change requires evaluating current species-wide patterns of habitat utilization and how these are determined by the local environment. These efforts, however, can be limited by a lack of data on distribution of the species, which are particularly difficult to collect in the case of air-breathing marine predators in high latitude systems. We present here a retrospective analysis on the distributional patterns of both Weddell (Leptonychotes weddellii) and crabeater seals (Lobodon carcinophaga) throughout their circumpolar ranges, using satellite telemetry data obtained over a time span of three decades (1990 to 2010s). Raw Argos tracks (nWeddell = 132; ncrabeater = 115), were filtered using a Switching State Space Model, and the tracking-derived behaviors (transit, foraging) were used to construct localized habitat models based on sea ice and bathymetry derived variables using binary Generalized Additive Mixed Models. We found differences in the effects and significance that environmental covariates had on the distribution at the local scale. The development of local habitat models for the entire range of these species will allow us to understand the ability of each species to cope with the anticipated environmental changes in their habitat.

The Expert Group on Birds and Marine Mammals (EG-BAMM) has initiated the "Retrospective Analysis of Antarctic Tracking Data" (RAATD) program. This project aims to create a predator community-wide assessment of habitat use in the entire the Southern Ocean. Identifying the basic habitat requirements of Antarctic predators is fundamental to understanding how they will respond to the human-induced challenges of commercial fisheries and climate change. This understanding can only be achieved if the underlying linkages to physical processes are related to animal movements. As part of this effort we are collating and synthesizing the available data on the foraging and movement patterns of Weddell and crabeater seals. While Weddell seals are one of the best studied top predators of the Southern Ocean, significantly less is known about crabeater seals, which are one of the most numerous mammals on the planet. We have synthesized the available tracks on these two seal species for comparison. We compare tracks from a 113 Weddell seals from the Weddell sea, the Antarctic Peninsula, East Antarctica and the Ross Sea and 53 crabeater seals from the Antarctic Peninsula and the Weddell Sea. The foraging behaviour of Weddell seals is surprising similar across the different regions, with dive durations ranging from 8.6 to 12.6 minutes with average ranging between 43 to 69 meters. Weddell seals tended to remain on the continental shelf and had similar movement patterns covering 7 to 13 km/day. In contrast crabeater seals moved greater absolute distances and greater distances per day ranging between 19.2 and 33.6 km/day. Further, their use of the continental shelf habitat varied with 85% of the crabeater seals on the wAP remaining on the shelf while only 24% remained on the shelf in the Weddell Sea.