Context drives movement patterns in a mobile marine predator

Nicolas Lubitz; Ryan Daly; John D Filmalter; Marcus Sheaves; Paul D Cowley; Tor F Naesje; Adam Barnett

doi:10.1186/s40462-023-00390-5

Context drives movement patterns in a mobile marine predator

Mov Ecol. 2023 May 24;11(1):28. doi: 10.1186/s40462-023-00390-5.

Authors

Nicolas Lubitz^{1

2}, Ryan Daly^{3

4}, John D Filmalter⁴, Marcus Sheaves⁵, Paul D Cowley⁴, Tor F Naesje⁶, Adam Barnett^{5

7}

Affiliations

¹ Marine Data Technology Hub, College of Science and Engineering, James Cook University, Townsville City, QLD, Australia. nicolas.lubitz@my.jcu.edu.au.
² Biopixel Oceans Foundation, Cairns, QLD, Australia. nicolas.lubitz@my.jcu.edu.au.
³ Oceanographic Research Institute, Marine Parade, PO Box 10712, 4056, Durban, South Africa.
⁴ South African Institute for Aquatic Biodiversity (SAIAB), Private Bag, 1015, 6140, Makhanda, South Africa.
⁵ Marine Data Technology Hub, College of Science and Engineering, James Cook University, Townsville City, QLD, Australia.
⁶ Norwegian Institute for Nature Research, P.O. Box 5685, NO- 7485, Torgarden, Trondheim, Norway.
⁷ Biopixel Oceans Foundation, Cairns, QLD, Australia.

Abstract

Intra-specific variability in movement behaviour occurs in all major taxonomic groups. Despite its common occurrence and ecological consequences, individual variability is often overlooked. As a result, there is a persistent gap in knowledge about drivers of intra-specific variability in movement and its role in fulfilling life history requirements. We apply a context-focused approach to bull sharks (Carcharhinus leucas), a highly mobile marine predator, incorporating intra-specific variability to understand how variable movement patterns arise and how they might be altered under future change scenarios. Spatial analysis of sharks, acoustically tagged both at their distributional limit and the centre of distribution in southern Africa, was combined with spatial analysis of acoustically tagged teleost prey and remote-sensing of environmental variables. The objective was to test the hypothesis that varying resource availability and magnitude of seasonal environmental change in different locations interact to produce variable yet predictable movement behaviours across a species' distribution. Sharks from both locations showed high seasonal overlap with predictable prey aggregations. Patterns were variable in the centre of distribution, where residency, small- and large-scale movements were all recorded. In contrast, all animals from the distributional limit performed 'leap-frog migrations', making long-distance migrations bypassing conspecifics in the centre of distribution. By combining multiple variables related to life history requirements for animals in different environments we identified combinations of key drivers that explain the occurrence of differing movement behaviours across different contexts and delineated the effects of environmental factors and prey dynamics on predator movement. Comparisons with other taxa show striking similarities in patterns of intra-specific variability across terrestrial and marine species, suggesting common drivers.

Keywords: Animal movement; Birds; Bull sharks; Context; Environmental change; Intra-specific variability; Marine predators; Resource availability.