Sex, body size, and boldness shape the seasonal foraging habitat selection in southern elephant seals

Abstract

Selecting foraging habitat is a fundamental behavior in the life of organisms as it directly links resource acquisition to fitness. Differences in habitat selection among individuals may arise from several intrinsic and extrinsic factors, and yet, their interaction has been given little attention in the study of wild populations. We combine sex, body size, and boldness to explain individual differences in the seasonal foraging habitat selection of southern elephant seals (Mirounga leonina) from the Kerguelen Archipelago. We hypothesize that habitat selection is linked to the trade‐off between resource acquisition and risk, and that individuals differ in their position along this trade‐off because of differences in reproductive strategies, life stages, and metabolic requirements. Before the post‐molt foraging trip, we used a novel object approach test to quantify the boldness of 28 subadult and adult females and 42 subadult males and equipped them with data loggers to track their movements at sea. Subadult males selected neritic and oceanic habitats, whereas females mostly selected less productive oceanic habitats. Both sexes showed a seasonal shift from Antarctic habitats in the south in the summer to the free of ice subantarctic and subtropical habitats in the north in the winter. Males avoided oceanic habitats and selected more productive neritic and Antarctic habitats with body size mostly in the winter. Bolder males selected northern warmer waters in winter, while shyer ones selected the Kerguelen plateau and southern colder oceanic waters. Bolder females selected the Kerguelen plateau in the summer when prey profitability is assumed to be the highest. This study not only provides new insights into the spatiotemporal foraging ecology of elephant seals in relation to personality but also emphasizes the relevance of combining several intrinsic and extrinsic factors in understanding among‐individual variation in space use essential in wildlife management and conservation.

Track and dive-based movement metrics do not predict the number of prey encountered by a marine predator

“…When leaving the Kerguelen Islands, SES seals spread in all directions in the Indian section of the Southern Ocean and consequently forage in areas with varying conditions [Fig. 1 , 67 , 68 , 78 ]. This likely results in targeting different types of prey with varying characteristics such as size, energetical and nutritional content, accessibility, and digestibility [ 80 , 85 ].…”

“…In addition to among-individual variation in the plastic response to varying experienced environmental conditions, variation among individuals can emerge from intrinsic factors [ 151 , 152 ]. For example, SES select distinct foraging habitats, varying in their productivity, level of competition and predation, and ice cover dynamics, with sex [ 66 , 68 ], age [ 153 ], and temperament [ 78 ]. The diet of SES is mainly composed by fish and squid species [ 82 , 84 , 154 , 155 ] and their relative proportions vary between individuals with sex [ 82 ] and age [ 86 , 87 ].…”

“…They predominantly forage pelagically in the interfrontal oceanic zone [ 66 – 68 ], where they target oceanic features of higher prey density [ 69 – 71 ] such as (sub)mesoscale eddies and fronts [ 72 – 75 ], the eastward Kerguelen plume [ 76 , 77 ], and areas with shallower Circumpolar Deep Water [ 15 ]. SES exhibit a high segregation among individuals in their core foraging areas characterized by distinct topographic and oceanic features [ 66 , 68 , 78 ] to which they are highly faithful at adult age [ 79 – 81 ]. The diet of SES is predominantly composed of squid and fish [ 82 – 85 ] for which the relative proportion could vary with sex [ 82 ], age [ 86 , 87 ], habitat type [ 80 , 85 ], season [ 84 ], and year [ 88 ].…”

Resource manipulation reveals interactive phenotype‐dependent foraging in free‐ranging lizards

“…Differential foraging among BTs can ultimately link behavioural variation with niche specialisation (sensu Bolnick et al, 2003), in which individuals utilise different resources or habitats that fit better with their foraging tactics, resulting in spatial and/or temporal heterogeneity in resource-consumer dynamics (Allegue et al, 2022;Toscano et al, 2016).…”