The ontogeny of at-sea behaviour in male southern elephant seals (Mirounga leonina) at Marion Island

Lasch, Kiara G.; Tosh, Cheryl Ann; Bester, Marthán N; Bruyn, P J Nico de

doi:10.1016/j.jembe.2022.151833

Cited by 2 publications

(1 citation statement)

References 47 publications

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“…This is interesting because the overall mean survival probability of the two groups differs (Figure 3). This may be related to predation pressure or foraging behavior as dive depth and prey search methods differ according to the physiological ability of males of different developmental stages (Lasch et al, 2023).…”

Section: Discussionmentioning

confidence: 99%

Modeling climate influences on male survival in the highly polygynous southern elephant seal (Mirounga leonina)

Volzke,

Cleeland,

McMahon

et al. 2024

Ecosphere

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The Southern Ocean, its ecosystem, and inhabitants are vulnerable to climate‐mediated shifts in habitat conditions. These changes can affect marine predators in the long term through changes in the distribution, density, and quality of prey. To understand how these changes affect vital rates requires longitudinal studies integrating demography and environmental states. We analyzed 22 years of capture–mark–recapture data to quantify the influence of broad‐scale climate on the survival of male southern elephant seals from Macquarie Island, Tasmania, Australia. Weaning mass was incorporated as a quadratic predictor of survival to account for the known influence of maternal investment. First‐year survival was greatest for weaners weighing 160 kg. Subsequent developmental stages were grouped into juvenile, subordinate, and breeding adult states to reflect the known life history of individuals. We found increased juvenile and subordinate survival with positive values of the previous years' Southern Annular Mode. This is likely due to the northward shift of westerly winds increasing productivity and prey availability in the Sub‐Antarctic region. In contrast to females of this population, the Southern Oscillation Index did not affect male survival. In this highly polygynous mating system, sex‐dependent differences in foraging behavior may be causing the small number of successful breeding adult males to be less susceptible to external influences after reaching the minimum age and body size required to be socially competitive for mating. These extremely large bulls will breed with multiple females and thus make a disproportionate contribution to the gene pool of the next generation. Considering the susceptibility of males to climate influences is therefore highly relevant to assessing the future adaptive capability of the species.

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Section: Discussionmentioning

confidence: 99%

Modeling climate influences on male survival in the highly polygynous southern elephant seal (Mirounga leonina)

Volzke,

Cleeland,

McMahon

et al. 2024

Ecosphere

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Extreme dietary specialisation in adult male southern elephant seals: determining variation between individual trophic diets

Cormack,

Slavich,

Negrete

et al. 2023

Mar. Ecol. Prog. Ser.

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Although dietary studies have provided important insights into the causes and ramifications of diet variation for the southern elephant seal (SES) (Mirounga leonina), adult males are comparatively underrepresented within that literature. Individual males can vary morphologically as well as behaviourally, leading to differences in their life history trajectories and outcomes. Therefore, to improve our understanding of the male diet, we sought to determine the degree of dietary variation between as well as within individuals from the West Antarctic Peninsula. Secondly, we investigated whether individual morphological traits, seasonality, and year influenced their dietary variation. Whiskers were sampled from 31 adult male seals and used to measure the bulk stable isotope nitrogen (δ15N). We sequentially segmented each whisker to create a time series of datapoints for each individual, allowing us to compare δ15N variation within each seal as well as assess variation between the seals. We then investigated the relationships between male dietary variation and body length, girth, season, and year. We found that adult male SESs maintained an extremely specialised diet. Variation between individuals was strongly correlated with their body size, with larger seals feeding higher up the trophic web. Interestingly, seasonality and year both influenced variation within the seals’ diets, but only year was seen to influence the variability between seals. We discuss the possible causes and ramifications of dietary specialisation for the SES and highlight the need for combined tracking and stable isotope investigations to improve our understanding of the ontogeny of the seals’ dietary specialisation.

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The ontogeny of at-sea behaviour in male southern elephant seals (Mirounga leonina) at Marion Island

Cited by 2 publications

References 47 publications

Modeling climate influences on male survival in the highly polygynous southern elephant seal (Mirounga leonina)

Modeling climate influences on male survival in the highly polygynous southern elephant seal (Mirounga leonina)

Extreme dietary specialisation in adult male southern elephant seals: determining variation between individual trophic diets

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