Body contact and synchronous diving in long-finned pilot whales

Aoki, Kosuke; Sakai, Mai; Miller, Patrick J. O.; Visser, Fleur; Sato, Katsufumi

doi:10.1016/j.beproc.2013.06.002

Cited by 30 publications

(28 citation statements)

References 33 publications

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“…, or deeper than 5 m in Aoki et al. ). To inform these thresholds by behavior, we used mixture models to classify IBI data variables that we expected to reflect the animals' need to take repeated breaths.…”

Section: Methodsmentioning

confidence: 91%

“…) and one whale (gm10_144a) was tagged with a logger that recorded three‐axis acceleration, depth, and speed but neither magnetic field nor acoustics (PD3GT Little Leonardo, Aoki et al. ). Magnetometer data were also missing for one tag record in 2008 (gm08_154d) due to sensor failure.…”

Section: Methodsmentioning

confidence: 99%

“…); long‐finned pilot whales have also been shown to perform closely synchronized surface and underwater movements (Senigaglia and Whitehead , Aoki et al. ). Similar to other toothed whales, their echolocation clicks, with terminal series of rapid clicks known as buzzes indicating prey capture attempts (Miller et al.…”

Section: Introductionmentioning

confidence: 99%

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Individual, ecological, and anthropogenic influences on activity budgets of long‐finned pilot whales

et al. 2017

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Abstract. Time allocation to different activities and habitats enables individuals to modulate their per-ceived risks and access to resources and can reveal important trade-offs between fitness-enhancing activities (e.g., feeding vs. social behavior). Species with long reproductive cycles and high parental investment, such as marine mammals, rely on such behavioral plasticity to cope with rapid environmental change, including anthropogenic stressors. We quantified activity budgets of free-ranging long-finned pilot whales in order to assess individual time trade-offs between foraging and other behaviors in different individual and ecological contexts, and during experimental sound exposures. The experiments included 1-2 and 6-7 kHz naval sonar exposures (a potential anthropogenic stressor), playback of killer whale (a potential predator/competitor) vocalizations, and negative controls. We combined multiple time series data from digital acoustic recording tags (DTAG) as well as group-level social behavior data from visual observations of tagged whales at the surface. The data were classified into near-surface behaviors and dive types (using a hidden Markov model for dive transitions) and aggregated into time budgets. On average, individuals (N = 19) spent most of their time (69%) resting and transiting near surface, 21% in shallow dives (depth <40 m), and only 10% of their time in deep foraging dives, of which 65% reached a depth 10 m from the sea bottom. Individuals in the largest of three body size classes or accompanied by calves tended to spend more time foraging than others. Simultaneous tagging of pairs of individuals showed that up to 50% of the activity budget was synchronized between conspecifics with decreased synchrony during foraging periods. Individuals spent less time foraging when forming larger non-vocal aggregations of individuals in late afternoons, and more time foraging when in the mid-range of water depths (300-400 m) available in the study area (50-700 m). Individuals reduced foraging time by 83% (29-96%) during their first exposure to sonar, but not during killer whale sound playbacks. A relative increase in foraging during repeat sonar exposures indicated habituation or change in response tactic. We discuss the possible adaptive value of these trade-offs in time allocation to reduce individual conflict while maintaining benefits of group living.

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Section: Methodsmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

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Individual, ecological, and anthropogenic influences on activity budgets of long‐finned pilot whales

et al. 2017

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“…This indicates that the whales that stayed close to each other at the surface also swam in close proximity underwater. We cannot ascertain the meaning of this behavior based on a few observations; however, similar behavior has been observed in other deep-diving Odontoceti, and it has been suggested to have a social function (Aoki et al 2013). Alternatively, other sperm whales might have been attracted to the flashing LED of the cameras because they were likely to see the lights being produced by the suction-cupattached tag if they stayed close to the tagged whale.…”

Section: Five Classes Of Still Images Obtained From Animalborne Camermentioning

confidence: 81%

Visual and behavioral evidence indicates active hunting by sperm whales

Aoki¹,

Amano²,

Kubodera³

et al. 2015

Mar. Ecol. Prog. Ser.

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It is hypothesized that sperm whales employ active pursuit strategies for hunting prey, mainly deep-sea squid at great depths, but no visual evidence has been obtained to confirm this. We recorded the hunting behavior of sperm whales using animal-borne cameras and accelerometers simultaneously deployed on 17 whales, and obtained 42.8 h of diving data, including 17 715 images. A statistical comparison indicated no clear effect of light (with or without flashing white lights from cameras) on diving behavior of tagged whales. Although 98.5% of the still images were of empty water and uninformative, 5 classes of images with visible material were identified: (1) suspended material, possibly squid ink (n = 17), (2) unidentified particles (n = 4), (3) possible animal body parts (n = 2), (4) other sperm whales (n = 221), and (5) the seafloor (n = 8). All image classes were recorded at deeper depths (mean ± SD = 785 ± 140 m), except Class 4 images, which were recorded only at depths < 339 m, suggesting that tagged whales swam alone while foraging at great depths. Simultaneous use of speed and image sensors revealed that Class 1 images were associated with bursts of speed up to approximately twice (3.3 ± 1.0 m s

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“…Previously these have been used in conjunction with multiple time-depth recorder deployments to examine synchrony in diving behaviour [19,20]. Only one study of penguins has examined sociality during at-sea foraging using animalattached cameras on single focal animals [21].…”

Section: Introductionmentioning

confidence: 99%

Images as proximity sensors: the incidence of conspecific foraging in Antarctic fur seals

et al. 2015

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Background:Although there have been recent advances in the development of animal-attached 'proximity' tags to remotely record the interactions of multiple individuals, the efficacy of these devices depends on the instrumentation of sufficient animals that subsequently have spatial interactions. Among densely colonial mammals such as fur seals, this remains logistically difficult, and interactions between animals during foraging have not previously been recorded. Results:We collected data on conspecific interactions during diving at sea using still image and video cameras deployed on 23 Antarctic fur seals. Animals carried cameras for a total of 152 days, collecting a total of 38,098 images and 369 movies (total time 7.35 h). Other fur seals were detected in 74 % of deployments, with a maximum of five seals detected in a single image (n = 122 images, 28 videos). No predators other than conspecifics were detected. Detection was primarily limited by light conditions, since conspecifics were usually further from each other than the 1-m range illuminated by camera flash under low light levels. Other seals were recorded at a range of depths (average 27 ± 14.3 m, max 66 m). Linear mixed models suggested a relationship between conspecific observations per dive and the number of krill images recorded per dive. In terms of bouts of dives, other seals were recorded in five single dives (of 330) and 28 bouts of dives <2 min apart (of 187). Using light conditions as a proxy for detectability, other seals were more likely to be observed at the bottom of dives than during descent or ascent. Seals were also more likely to be closer to each other and oriented either perpendicular or opposing each other at the bottom of dives, and in the same or opposite direction to each other during ascent. Conclusions:These results are contrary to animal-attached camera observations of penguin foraging, suggesting differing group-foraging tactics for these marine predators. Group foraging could have consequences for models linking predator behaviour to prey field densities since this relationship may be affected by the presence of multiple predators at the same patch.

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Body contact and synchronous diving in long-finned pilot whales

Cited by 30 publications

References 33 publications

Individual, ecological, and anthropogenic influences on activity budgets of long‐finned pilot whales

Individual, ecological, and anthropogenic influences on activity budgets of long‐finned pilot whales

Visual and behavioral evidence indicates active hunting by sperm whales

Images as proximity sensors: the incidence of conspecific foraging in Antarctic fur seals

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