Behavioral responses of two species of dolphins to novel video footage: An exploration of sex differences

Abstract

This study assessed the interest toward novel video clips as enrichment stimuli in two species of captive dolphins (Tursiops: n = 11; Steno: n = 5). Videos were played at underwater viewing windows while the animals were housed with conspecifics, and responses were subsequently analyzed based on general content of each novel video. Interest levels (i.e., percentage of time watching and behavioral rate) were compared between species and within species across video categories. While the varied video contexts did not produce significant differences among the time spent watching or behaviors observed, species differences and sex differences were noted. Rough-toothed dolphins displayed significantly more behaviors, particularly interest and bubble behaviors, than bottlenose dolphins, with no differences observed between the species for the percentage of time spent watching. Among bottlenose dolphins, males watched the television longer, and responded behaviorally significantly more, displaying a higher rate of bubble and aggressive behaviors than females. Male rough-toothed dolphins displayed significantly more aggressive behaviors than females, with no other sex differences noted. Overall, these data suggest that television may serve as a useful enrichment device for certain individuals and species of cetaceans, as well as a cognitive experimental tool, as long as sex, species, and individual differences are taken into consideration when interpreting results.

Enrichment with classical music enhances affiliative behaviours in bottlenose dolphin

“…The social support function is supported by the fact that affiliative behaviours appear in different stressful events in the dolphin society (Waples and Gales, 2002;Connor et al, 2006a;Serres et al, 2020Serres et al, , 2021. However, this explanation seems unlikely in our case, as no increases in aggressive behaviors or decreases in positive staterelated behaviours were expressed when classical music was provided, as it is observed under conditions of acoustical stress (Couquiaud, 2005;Serres and Delfour, 2017) or when a novel stimulus is presented (Winship and Eskelinen, 2018). It is more likely that the increased social behaviours observed in this study represent an expression of positive emotions.…”

“…jump, breathe, etc.). Behavioural data collection from videos was performed with a focal animal, continuous sampling method using the Observer XT software (Ver.12.5, Noldus, Gröeningen, The Netherlands), according to the ethogram reported in Table s2, which was specifically realized for this experiment by taking several published studies as sources of behaviours and definitions (Galhardo et al, 1996;Marten et al, 1996;Samuels and Gifford, 1997;Müller et al, 1998;Connor et al, 2000;Miles and Herzing, 2003;Sekiguchi and Kohshima, 2003;Connor et al, 2006a;Holobinko and Waring, 2010;Jensen et al, 2013;Clegg et al, 2015Clegg et al, , 2017aClegg et al, , 2017cDudzinski and Ribic, 2017;Hanna et al, 2017;Serres and Delfour, 2017;Clegg and Delfour, 2018b;Winship and Eskelinen, 2018;Moreno and Macgregor, 2019;Serres et al, 2020Serres et al, , 2021. Collected data was used to calculate relative duration of expression (% of observation time) for behavioural states and the frequency (events/hr) for behavioural events.…”

“…In fact, responses are depending on several aspects such as, among others, the species, the sex, the social group and how the enrichment is provided. For instance, the presentation of the exact same set of stimuli elicited more interest and bubble behavior in rough-toothed dolphins than in bottlenose dolphins, and more aggressive behaviors were expressed by males than females in both species (Winship and Eskelinen, 2018). Moreover, presenting the enrichment with random schedules and session lengths thereby avoiding habituation (Kuczaj et al, 2002), and when the animals are at a high activation level, e.g., after a training session (Perez et al, 2018) helps keeping the animals' interest toward the enrichment device.…”

“…Another type of sensory enrichment is visual media broadcasted on a screen, in the form of videos. Hanna and co-authors (2017) analysed behavioral responses of a killer whale to different videos presented with and without sound, and Winship and Eskelinen (2018) observed behavioral responses of two groups of dolphins toward different video categories.…”

“…The behavioral response to this type of enrichment is less consistent than that towards the provision of objects, as it elicits attraction (Hanna et al, 2017), but can also trigger aggressive behaviors towards the enrichment (Winship and Eskelinen, 2018). To our knowledge, no studies have assessed the effect of acoustical enrichment in cetaceans without any other sense at stake.…”