Hidden Markov models reveal complexity in the diving behaviour of short-finned pilot whales

Quick, Nicola J.; Isojunno, Saana; Sadykova, Dinara; Bowers, Matthew T.; Nowacek, Douglas P.; Read, Andrew J.

doi:10.1038/srep45765

Cited by 49 publications

(63 citation statements)

References 57 publications

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“…The lack of a single foraging dive type is consistent with recent findings of Quick et al. () who described several dive types representing different levels of foraging effort in short‐finned pilot whales. Furthermore, social sounds and dive synchrony occurred in both foraging and non‐foraging contexts, indicating that social interactions occurred across the behavioral repertoire.…”

Section: Discussionsupporting

confidence: 91%

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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: Discussionsupporting

confidence: 91%

“…, Quick et al. ). Resting time often has both a physiologically enforced or “conserved” component (here, a recovery period required after a breath‐hold dive) and a “free” component that can be re‐allocated to other behaviors that, in turn, may be more conserved in the time budget (Dunbar et al.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2017

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“…To assess the influence of these features on pilot whale foraging behavior, we used the 200 m isobath, generated from GEBCO bathymetric grids (30 arc-second resolution; www.gebco.net/data_and_products/ gridded _ bathymetry_data/), as a proxy for the location of the shelf break. Short-finned pilot whales typically forage at depths of 200−1000 m in our study area (Quick et al 2017), so consequently we identified canyons by examining valleys in the continental shelf slope that were evident in both the 200 m and 1000 m isobaths. We defined canyons as deep, steep-sided valleys that extended into the continental shelf for > 5 km in the cross-shelf direction of the 200 m isobath (Fig.…”

Section: Environmental Datamentioning

confidence: 99%

“…are deep-diving odontocetes that occur in shelf break regions and forage at depths of > 800 m (Baird et al 2002, Heide-Jør-gensen et al 2002, Garrison 2007, Aguilar Soto et al 2008, Jensen et al 2011, Baird 2016, Quick et al 2017. Information on the spatial habitat use of pilot whales in the northwest Atlantic is limited and, until recently, most information on their habitat use in this region was derived from shipboard and aerial surveys (although see Mate et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Movement and foraging behavior of short-finned pilot whales in the Mid-Atlantic Bight: importance of bathymetric features and implications for management

Thorne¹,

Foley²,

Baird³

et al. 2017

Mar. Ecol. Prog. Ser.

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“…For these species, characterising flight modes may be more relevant than distinguishing between transit and resident movement, because of the implications on their energy budget. Such characterisation requires either the use of additional sensors, such as accelerometers, or the introduction of a third movement dimension (altitude), which is conceptually comparable to the use of depth when modelling diving behaviour of marine animals (Isojunno & Miller, ; Quick et al., ). Birds adopt different strategies to move through air, depending on their size, body structure, reasons for moving and environmental and weather conditions (Duerr et al., ; Hedenstrom, ; Lanzone et al., ).…”

Section: Introductionmentioning

confidence: 99%

State‐space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies

Pirotta

Katzner

Miller³

et al. 2018

Functional Ecology

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Characterising the spatiotemporal variation of animal behaviour can elucidate the way individuals interact with their environment and allocate energy. Increasing sophistication of tracking technologies paired with novel analytical approaches allows the characterisation of movement dynamics even when an individual is not directly observable. In this study, high‐resolution movement data collected via global positioning system (GPS) tracking in three dimensions were paired with topographical information and used in a Bayesian state‐space model to describe the flight modes of migrating golden eagles (Aquila chrysaetos) in eastern North America. Our model identified five functional behavioural states, two of which were previously undescribed variations on thermal soaring. The other states comprised gliding, perching and orographic soaring. States were discriminated by movement features in the horizontal (step length and turning angle) and vertical (change in altitude) planes and by the association with ridgelines promoting wind deflection. Tracked eagles spent 2%, 31%, 38%, 9% and 20% of their daytime in directed thermal soaring, gliding, convoluted thermal soaring, perching and orographic soaring, respectively. The analysis of the relative occurrence of these flight modes highlighted yearly, seasonal, age, individual and sex differences in flight strategy and performance. Particularly, less energy‐efficient orographic soaring was more frequent in autumn, when thermals were less available. Adult birds were also better at optimising energy efficiency than subadults. Our approach represents the first example of a state‐space model for bird flight mode using altitude data in conjunction with horizontal locations and is applicable to other flying organisms where similar data are available. The ability to describe animal movements in a three‐dimensional habitat is critical to advance our understanding of the functional processes driving animals’ decisions. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13180/suppinfo is available for this article.

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Hidden Markov models reveal complexity in the diving behaviour of short-finned pilot whales

Cited by 49 publications

References 57 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

Movement and foraging behavior of short-finned pilot whales in the Mid-Atlantic Bight: importance of bathymetric features and implications for management

State‐space modelling of the flight behaviour of a soaring bird provides new insights to migratory strategies

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