Influence of environment, morphology, and instrument size on lactating northern fur seal Callorhinus ursinus foraging behavior on the Lovushki Islands, Russia

Skinner, J.; Burkanov, Vladimir N.; Andrews, Russel D.

doi:10.3354/meps10038

Cited by 11 publications

(5 citation statements)

References 37 publications

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“…Thus, once animals reach a large enough size that they are able to efficiently exploit these depths, the benefits of additional aerobic stores may be minimal. A similar response has been found in adult female northern fur seals Callorhinus ursinus, whose body size does not appear to be a driving factor in the duration of dives (Skinner et al 2012).…”

Section: Effects Of Individual Differences On Foraging Behavioursupporting

confidence: 74%

Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals

Hoskins¹,

Costa²,

Wheatley³

et al. 2015

Mar. Ecol. Prog. Ser.

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Phenotypic variation and individual experience can create behavioural and/or dietary variation within a population. This may reduce intra-specific competition, creating a buffer to environmental change. This study examined how intrinsic variation affects foraging behaviour of Australian fur seals. Foraging movements of 29 female Australian fur seals were recorded using FastLoc GPS and dive behaviour recorders. For each individual, body mass, flipper length and axis length were recorded, a tooth was sampled to determine age, and milk was collected for diet analysis. Clustering of fatty acid dietary analysis revealed 5 distinct groups in the population. Behaviour was described using 19 indices, which were then reduced to 7 principal components (> 80% of the behavioural variation). Bayesian mixed effect models were developed to describe the relationship between these components and intrinsic variation. No association was found between diet and age or body shape; however, age had a negative relationship with component 1 (27% of variation). Older females spent less time at-sea and foraged nearer to the colony. Age had an effect on component 5 (7% of variation), which represented haul-outs and dive depth; older females made fewer visits to haul-out sites and dived deeper to the benthos. This suggests that as animals age they are able to utilise prior knowledge to exploit nearby foraging sites that younger animals are either unaware of, or have yet to gain the experience required to efficiently utilise. Mass had a negative effect on components representing the directedness of a foraging trip, suggesting heavier individuals were more likely to travel directly to a foraging site.

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Section: Effects Of Individual Differences On Foraging Behavioursupporting

confidence: 74%

Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals

Hoskins¹,

Costa²,

Wheatley³

et al. 2015

Mar. Ecol. Prog. Ser.

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“…2), we included the frontal surface area (FSA) of the tag(s) as a covariate. While FSA may not be the best representation of the drag an animal experiences (Kay et al , 2019; Kyte et al , 2019), it has been used previously for this species (Skinner et al , 2012) and was the best metric we could reliably calculate given the dataset and the free-ranging nature of seals in our study. We calculated the total FSA (sum across all tags) and the effective FSA (the FSA of the anterior tag and any excess area by the second tag) to account for the fact that TDRs were placed directly behind the often larger satellite tag.…”

Section: Methodsmentioning

confidence: 99%

Factors affecting energy expenditure in a declining fur seal population

McHuron

Sterling

Costa

et al. 2019

Conservation Physiology

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Quantifying metabolic rates and the factors that influence them is key to wildlife conservation efforts because anthropogenic activities and habitat alteration can disrupt energy balance, which is critical for reproduction and survival. We investigated the effect of diving behaviour, diet and season on field metabolic rates (FMR) and foraging success of lactating northern fur seals (Callorhinus ursinus) from the Pribilof Islands during a period of population decline. Variation in at-sea FMR was in part explained by season and trip duration, with values that ranged from 5.18 to 9.68 W kg−1 (n = 48). Fur seals experienced a 7.2% increase in at-sea FMR from summer to fall and a 1.9% decrease in at-sea FMR for each additional day spent at sea. There was no effect of foraging effort, dive depth or diet on at-sea FMR. Mass gains increased with trip duration and were greater in the fall compared with summer, but were unrelated to at-sea FMR, diving behaviour and diet. Seasonal increases in at-sea FMR may have been due to costs associated with the annual molt but did not appear to adversely impact the ability of females to gain mass on foraging trips. The overall high metabolic rates in conjunction with the lack of any diet-related effects on at-sea FMR suggests that northern fur seals may have reached a metabolic ceiling early in the population decline. This provides indirect evidence that food limitation may be contributing to the low pup growth rates observed in the Pribilof Islands, as a high metabolic overhead likely results in less available energy for lactation. The limited ability of female fur seals to cope with changes in prey availability through physiological mechanisms is particularly concerning given the recent and unprecedented environmental changes in the Bering Sea that are predicted to have ecosystem-level impacts.

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“… Georges et al , (2000b) ; 5. average of pelagic divers: Kuhn (2011) ; 6. Skinner et al. , (2012) ; 7.…”

Section: Methodsmentioning

confidence: 99%

Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

Ladds

Rosen

Gerlinsky

et al. 2020

Conservation Physiology

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Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

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Influence of environment, morphology, and instrument size on lactating northern fur seal Callorhinus ursinus foraging behavior on the Lovushki Islands, Russia

Cited by 11 publications

References 37 publications

Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals

Influence of intrinsic variation on foraging behaviour of adult female Australian fur seals

Factors affecting energy expenditure in a declining fur seal population

Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

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