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Acute and chronic behavioral effects of kelp gull micropredation on southern right whale mother-calf pairs off Peninsula Valdes, Argentina

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  • Taylor R. Azizeh, Aarhus University
  • ,
  • Kate R. Sprogis, Murdoch University
  • ,
  • Raquel Soley, Instituto de Conservación de Ballenas
  • ,
  • Mia L. K. Nielsen, University of Exeter
  • ,
  • Marcela M. Uhart, Southern Right Whale Health Monitoring Program, University of California at Davis
  • ,
  • Mariano Sironi, Instituto de Conservación de Ballenas, Southern Right Whale Health Monitoring Program, Universidad Nacional de Cordoba
  • ,
  • Carina F. Maron, Instituto de Conservación de Ballenas, Universidad Nacional de Cordoba
  • ,
  • Lars Bejder, Murdoch University, University of Hawaii at Manoa
  • ,
  • Peter T. Madsen
  • Fredrik Christiansen

Kelp gulls Larus dominicanus (KG) feed on the skin and blubber of living southern right whales Eubalaena australis (SRWs) off Peninsula Valdes (PV), Argentina. The whales respond strongly to KG micropredation by changing their immediate (acute) behavior during attacks and their overall (chronic) surfacing pattern and body posture to minimize gull exposure. The energetic and large-scale behavioral consequences of these attacks are unknown. To address this knowledge gap, we quantified the effect size of both acute (during attacks) and chronic (not during attacks) responses by comparing the respiration rates, swim speed, and nursing behavior of PV SRWs to undisturbed (control) SRW mother-calf pairs in Head of Bight, Australia, using unmanned aerial vehicle focal follows. Even when gulls were not attacking, PV SRW mothers and calves demonstrated similar to 50 and similar to 25% higher respiration rates, respectively, than whales in Australia. During attacks, PV calf respiration rates increased by an additional 10%. PV SRW mothers also frequently (> 76% of respirations) exhibited irregular breathing postures, causing the whales to potentially expend extra energy by working against their natural buoyancy. Despite no significant increase in average maternal swim speed, 76 and 90% of gull attacks elicited strong behavioral reactions from mothers and calves, respectively. Overall, PV calves spent less time nursing during individual bouts compared to those in Australia but entered suckling position more frequently. Furthermore, kelp gulls seemed to show a preference for attacking previously wounded calves and at a higher rate. These chronic and acute behavioral effects may carry energetic costs, which could have long-term consequences for SRW survival and reproduction.

Original languageEnglish
JournalMarine Ecology Progress Series
Pages (from-to)133-148
Number of pages16
Publication statusPublished - Jun 2021

    Research areas

  • Behavioral disturbance, Micropredation, Respiration rate, Nursing, Swim speed, Unmanned aerial vehicle, Seabird-cetacean interactions, EUBALAENA-AUSTRALIS, LARUS-DOMINICANUS, ENERGY-EXPENDITURE, IMMUNE FUNCTION, MINKE WHALES, STRESS, RATES, POPULATION, PREDATION, PARASITES

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