Foraging behavior of northern fur seals closely matches the hierarchical patch scales of prey

Benoit‐Bird, Kelly J.; Battaile, Brian C.; Nordstrom, Chad A.; Trites, Andrew W.

doi:10.3354/meps10209

Cited by 52 publications

(45 citation statements)

References 76 publications

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“…This provided a mechanistic way of categorizing dive types, using interpretable movement signatures as diagnosed from the parameter values of our AR(2) vertical movement model. This contrasts with other classification schemes that distinguished dive types based on depth (e.g., , Goebel 2002, or used the torturous paths associated with prey patchiness (Benoit-Bird et al 2013a). Parameters corresponding to periodic solutions of the AR(2) process were termed active diving.…”

Section: Discussioncontrasting

confidence: 42%

Linking northern fur seal dive behavior to environmental variables in the eastern Bering Sea

et al. 2015

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Abstract. Northern fur seals (Callorhinus ursinus) breeding on the Pribilof Islands, Alaska have declined dramatically over the past 40 years. Effective conservation of northern fur seals depends on understanding the foraging behavior of adult females whose foraging success is linked to pup survival. We determined the foraging behavior for 11 tagged lactating female northern fur seals from the Pribilof Islands using a statespace modeling approach with an autoregressive movement model. To interpret at-sea behavior in the context of oceanic habitat, we spatially and temporally matched high-resolution reconstructed tracks to a set of environmental covariates that included: commercial groundfish catch, sea surface temperature, primary productivity, wind speed, depth and time of day. We used a Bayesian hierarchical framework to implement a multinomial regression model to link behavior to environmental covariates and account for the mismatch of scale between fur seal behavior and the environmental variables by incorporating an errorin-covariates approach into the hierarchical model. The Bayesian framework allowed us to build a single model to synthesize the information from all the northern fur seal foraging tracks and the available information about the underlying environmental conditions. Application of the approach indicated that the behavioral states for the northern fur seal were significantly related to the Alaska commercial groundfish catch, particularly walleye pollock (Gadus chalogramma).

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Section: Discussioncontrasting

confidence: 42%

Linking northern fur seal dive behavior to environmental variables in the eastern Bering Sea

et al. 2015

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“…Juvenile walleye pollock (Theragra chalcogramma) and gonatid squid are of particular importance during the summer and autumn in the eastern Bering Sea (Sinclair et al, 1994). Northern fur seals tend to feed at dusk and dawn, and dive to the deep scattering layer to feed on these small mesopelagic fishes (Gentry and Johnson, 1981;Gentry et al, 1986), including juvenile walleye pollock and Atka mackerel (Gentry and Johnson, 1981;Gentry et al, 1986;Benoit-Bird et al, 2013). It is unclear whether feeding in a pelagic habitat in pursuit of small elusive fish and squid is more successful using a ram-biting strategy and inertial transport rather than a suction feeding mode.…”

Section: Discussionmentioning

confidence: 99%

Feeding kinematics and performance of basal otariid pinnipeds, Steller sea lions (Eumetopias jubatus), and northern fur seals (Callorhinus ursinus): implications for the evolution of mammalian feeding

Marshall

Rosen

Trites

2015

Journal of Experimental Biology

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Feeding performance studies can address questions relevant to feeding ecology and evolution. Our current understanding of feeding mechanisms for aquatic mammals is poor. Therefore, we characterized the feeding kinematics and performance of five Steller sea lions (Eumetopias jubatus) and six northern fur seals (Callorhinus ursinus). We tested the hypotheses that both species use suction as their primary feeding mode, and that rapid jaw opening was related to suction generation. Steller sea lions used suction as their primary feeding mode, but also used a biting feeding mode. In contrast, northern fur seals only used a biting feeding mode. Kinematic profiles of Steller sea lions were all indicative of suction feeding (i.e. a small gape, small gape angle, large depression of the hyolingual apparatus and lip pursing). However, jaw opening as measured by gape angle opening velocity (GAOV) was relatively slow in Steller sea lions. In contrast to Steller sea lions, the GAOV of northern fur seals was extremely fast, but their kinematic profiles indicated a biting feeding mode (i.e. northern fur seals exhibited a greater gape, a greater gape angle and minimal depression of the hyolingual apparatus compared with Steller sea lions). Steller sea lions produced both subambient and suprambient pressures at 45 kPa. In contrast, northern fur seals produced no detectable pressure measurements. Steller sea lions have a broader feeding repertoire than northern fur seals, which likely enables them to feed on a greater variety of prey, in more diverse habitats. Based on the basal phylogenetic position of northern fur seals, craniodental morphological data of the Callorhinus lineage, and the performance data provided in this study, we suggest that northern fur seals may be exhibiting their ancestral feeding mode.

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“…Predators can respond to their environment, including prey availability, at multiple spatial scales (for example, [74,75]). Northern fur seals have been shown to respond to environmental factors from the scale of meters up to the entire foraging range [50,76]. Here, we found that, even at this coarse spatial scale, significant relationships exist between fur seal behavior and prey abundance.…”

Section: Study Limitations and Future Directionsmentioning

confidence: 59%

Linking northern fur seal behavior with prey distributions: the impact of temporal mismatch between predator studies and prey surveys

2015

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Background: An essential part of foraging ecology research is identifying how the distribution and abundance of prey influence predator behavior. However, in marine systems, temporal or spatial mismatches often exist between prey surveys and predator tracking periods, especially for species with large foraging ranges. Using northern fur seals (Callorhinus ursinus) as a model, we investigated how conclusions about predator-prey relationships change with increasing temporal disparity between predator tracking periods and prey surveys. To measure foraging behavior, northern fur seals (n = 20) from St. Paul Island (Alaska, USA) were equipped with satellite tracking transmitters and time-depth recorders from July to October 2006. Fur seal dive and movement metrics were examined in relation to the relative abundance of the fur seals' primary prey, walleye pollock (Gadus chalcogrammus), reported from the annual eastern Bering Sea groundfish survey. Relationships between foraging behavior metrics and prey abundance were examined within the Bering shelf survey grid cells at three timescales: within 2 weeks of the prey survey, within 1 month, and over the northern fur seal reproductive season (>4 months). Results:We found significant relationships between northern fur seal behavior and prey abundance, even with the limited sample size at the shortest temporal resolution (2 weeks). Changes in dive behavior that were associated with areas of abundant pollock (for example, increased vertical distance traveled and longer periods of diving) were consistent with previously reported metrics of pinniped foraging success. When behavioral metrics, such as vertical distance traveled and time spent diving, remained significantly related to prey abundance at multiple temporal scales, the relationship strength was reduced as temporal mismatch increased. Conclusion:Our results suggest that relationships between behavioral metrics and prey abundance vary as temporal mismatch increases between prey surveys and predator tracking periods. For northern fur seals, pollock surveys conducted early in the reproductive season may still provide information useful to examine predator-prey relationships as the reproductive season progresses, albeit with diminished predictive power. Understanding predator-prey relationships, including the impact of varying temporal scales, is particularly valuable for guiding research and conservation strategies for northern fur seals as the population continues to decline.

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Foraging behavior of northern fur seals closely matches the hierarchical patch scales of prey

Cited by 52 publications

References 76 publications

Linking northern fur seal dive behavior to environmental variables in the eastern Bering Sea

Linking northern fur seal dive behavior to environmental variables in the eastern Bering Sea

Feeding kinematics and performance of basal otariid pinnipeds, Steller sea lions (Eumetopias jubatus), and northern fur seals (Callorhinus ursinus): implications for the evolution of mammalian feeding

Linking northern fur seal behavior with prey distributions: the impact of temporal mismatch between predator studies and prey surveys

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