Prey encounters and spatial memory influence use of foraging patches in a marine central place forager

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Iorio-Merlo, Virginia
Graham, Isla
Hewitt, Rebecca
Aarts, Geert
Pirotta, Enrico
Hastie, Gordon D.
Thompson, Paul
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The Royal Society
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Given the patchiness and long-term predictability of marine resources, memory of high-quality foraging grounds is expected to provide fitness advantages for central place foragers. However, it remains challenging to characterise how marine predators integrate memory with recent prey encounters to adjust fine-scale movement and use of foraging patches. Here, we used two months of movement data from harbour seals (Phoca vitulina) to quantify the repeatability in foraging patches as a proxy for memory. We then integrated these data into analyses of fine-scale movement and underwater behaviour to test how both spatial memory and prey encounter rates influenced the seals’ Area Restricted Search (ARS) behaviour. Specifically, we used one month’s GPS data from 29 individuals to build spatial memory maps of searched areas, and archived accelerometery data from a subset of five individuals to detect prey catch attempts, a proxy for prey encounters. Individuals were highly consistent in the areas they visited over two consecutive month. Hidden Markov Models showed that both spatial memory and prey encounters increased the probability of seals initiating ARS. These results provide evidence that predators use memory to adjust their fine scale movement and this ability should be accounted for in movement models.
ARS , Spatial memory , Hidden Markov model , Accelerometer , Harbor seals , Repeatability
Iorio-Merlo, V., Graham, I., Hewitt, R., Aarts, G., Pirotta, E., Hastie, G. D. and Thompson, P. (2022) 'Prey encounters and spatial memory influence use of foraging patches in a marine central place forager', Proceedings of the Royal Society B, 289, 20212261 (10pp). doi: 10.1098/rspb.2021.2261