Behavioural Diversity Study in Bottlenose Dolphin (Tursiops truncatus) Groups and Its Implications for Welfare Assessments

Abstract

In the recent past, animal welfare studies have tried to determine the best animal welfare measures and indicators. Expression of behavioural diversity is considered a potential positive welfare indicator, and to the authors’ knowledge, it has not been validated nor studied in cetaceans. For the first time, a behavioural diversity study on bottlenose dolphins (Tursiops truncatus) groups was conducted at six European facilities. The study was carried out by the animal care staff, biologists and veterinarians and included 54 dolphins housed in several group compositions at the different participating facilities. The goal of our study was to analyse behavioural diversity in bottlenose dolphins at the group level to investigate how particular factors might impact the diversity of behaviours within the group and to discuss its implications for dolphin welfare assessments. Eight factors (i.e., “observer location”, “number of individuals”, “age class”, “sex”, “social grouping”, “presence/absence of leading male”, “presence/absence of visitors” and “enrichment provision”) impacted the behavioural diversity of the observed groups, while no significant impact of the factors “time of day” and “activity before/after observation” could be found. Our study showed the feasibility of this kind of approach for cetaceans under professional care and the relevance to considering this parameter in dolphin welfare studies, despite certain limitations that warrant further research.

Episodic-like memory in common bottlenose dolphins

“…Dolphins were tested individually in the dedicated pool where possible, but if not (e.g., when testing a dolphin with a calf), the other dolphin was kept distracted at the edge of the pool by a trainer. All dolphins used in this study were born and raised under human care and have been involved in different studies before this project, for example, on vocal communication, play behavior, 65 preferences tests and anticipatory behavior. 66 The dolphins under Zoomarine care are all trained to perform various behaviors for multiple reasons, e.g., medical or zoo performances, through operant conditioning with positive (and variable) reinforcement and social learning.…”

Investigating Unused Tools for the Animal Behavioral Diversity Toolkit

“…While richness has value as a diversity indicator, it has several limitations [ 44 ]. Behavioral richness (number of behaviors seen) does not take into account evenness or the number of observations, or the behavior types that were recorded [ 45 , 46 ]. This leaves the values to be easily skewed in a real-world setting, such as in studies that observed animals over differing lengths of time or used different sampling interval lengths [ 47 ].…”

Behavioural Impact of Captive Management Changes in Three Species of Testudinidae

“…There has been recent interest in using behavioural diversity measures, calculated from behavioural data, to provide an objective insight into the welfare of an individual, or group, of animals by determining how much variation is shown in their behavioural repertoire [31][32][33][34][35]. Greater behavioural diversity is generally accepted as a positive indicator of welfare [31,34,35]. This is based on the assumption that animals displaying varied behavioural repertories are having their behavioural needs met.…”

“…This is based on the assumption that animals displaying varied behavioural repertories are having their behavioural needs met. Alternately, when diversity is low an animal may be showing reduced overall behaviours due to lethargy or the performance of stereotypies [31,35].…”