Individual, ecological, and anthropogenic influences on activity budgets of long‐finned pilot whales
Benthic habitat
Hidden Markov model
0106 biological sciences
570
QH301 Biology
/dk/atira/pure/sustainabledevelopmentgoals/life_below_water; name=SDG 14 - Life Below Water
590
Deep diving mammal
DAS
DTAG
01 natural sciences
Activity synchrony
Ethogram
/dk/atira/pure/sustainabledevelopmentgoals/life_below_water
QH301
Anthropogenic noise
Naval sonar
Globicephala melas
13. Climate action
name=SDG 14 - Life Below Water
SDG 14 - Life Below Water
14. Life underwater
BDC
R2C
DOI:
10.1002/ecs2.2044
Publication Date:
2017-12-27T18:48:53Z
AUTHORS (8)
ABSTRACT
AbstractTime allocation to different activities and habitats enables individuals to modulate their perceived 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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