MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14845

ABSTRACT: Understanding animal foraging behaviour can answer pertinent questions in behavioural ecology and help conservation efforts. Baleen whales have extreme adaptations for feeding on some of the smallest animals. One species of special interest is the Bryde’s whale Balaenoptera edeni, which feeds in various ways across different ecosystems. No previous study on foraging kinematics exists for the vulnerable population of Inshore population of Bryde’s whales B. edeni brydei in South Africa. Over 2 consecutive years, we deployed multisensory camera-tag dataloggers on 8 Bryde’s whales in Plettenberg Bay, South Africa. Combining supervised and unsupervised clustering algorithms, we analysed 190 feeding lunges to investigate whether different foraging techniques were performed and, if so, at what depths. The whales showed 3 distinct ways of attacking their prey: (1) ‘slow lunges’, which started and concluded at a very low speed, regardless of the depth at which they were performed; (2) ‘neutral lunges’, occurring between 40 and 100 m depth, in which whales had high initial speeds and moved vertically in the acceleration phase of the lunge while being less acrobatic; (3) ‘ambush lunges’, used at shallow depths (<30 m), with the whale pitching upwards and accelerating faster compared to other techniques, often reaching the surface right after lunging. When engulfing prey, individual whales switched between different techniques throughout a deployment. Our findings form the basis of understanding the energetic costs of feeding techniques of this species, and for further investigation of any spatial-temporal factors that could impact the development of their foraging behaviour.