Making sense of intra-specific variation in movement behaviour of marine species

Background/Question/Methods

Animals rely on movement to find resources and escape predators, and their movement patterns can impact their resilience to environmental changes. Understanding the general migration patterns of animals has been the focus of research for decades, with a recent interest in intra-species variation. We are interested in identifying potential factors explaining intra-specific variation in movement at the population- and individual-level. We used movement and behavioural data collected through tracking devices for three marine species (Arctic tern, narwhal, and gentoo penguin) and link these data to environmental and physiological factors.

Results/Conclusions

For Arctic terns, we show that all studied populations share a few migration routes, but that there is substantial intra-specific variation in the timing, time spent in contact with the ocean, and directedness of the migration route. In particular, Arctic terns nesting in the Arctic arrived later at their colonies, and larger individuals had more direct migration. Using narwhals, we show that individuals from the same summering grounds use two different migration routes and that this choice affect the length of the migration and whether they use a direct migration or make extended stop overs on route. Finally, using gentoo penguin diving data, we show that blood oxygen capacity is correlated to dive efficiency, and that foraging behaviour is predictive of breeding status. We use these three case studies to highlight how intra-specific variation can be partitioned, and discuss potential mechanisms for these different sources of variation.