The Frequency of Solitary Behaviors in Captive Odontocetesis Modulated by Environmental and Social Factors

Abstract

The number of welfare-oriented studies is increasing in animals under human care, including odontocetes. However, validated welfare indicators are lacking for captive odontocetes. We studied the effect of several conditions (moment of the day, social grouping, public presence) and stimuli (enrichment, perturbations) on the solitary behaviour of Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis), East-Asian finless porpoises (N. a. sunameri) and bottlenose dolphins (Tursiops truncatus). The frequency of solitary play increased in the three groups in positive conditions and decreased in negative contexts, which confirms that play is a useful indicator of welfare for captive odontocetes. Jumping seem to be indicative of stress for finless porpoises but could be ambiguous for bottlenose dolphins: indicating both positive and negative excitation. Stereotypical behaviours for Yangtze finless porpoises and environment hitting behaviours for bottlenose dolphins could indicate mild stress or frustration. Vigilant behaviours are not clear indicators since a high frequency could reflect boredom, but a low frequency was observed in poor social conditions. Finally, we suggest that environmental rubbing should be investigated further since our results for this behaviour were not clear.

Social, Reproductive and Contextual Influences on Fecal Glucocorticoid Metabolites in Captive Yangtze Finless Porpoises (Neophocaena asiaeorientalis asiaeorientalis) and Bottlenose Dolphins (Tursiops truncatus)

“…Conversely, social separation appeared to influence YFP behavior. Separated animals have been observed spending prolonged and/or frequent periods of time in front of gates, either interacting with individuals on the other side or looking at them, increasing circular swimming patterns and being less playful [75,76]. Our observations of higher FGCM concentrations associated with separation in the YFP support the theory that these behavioral changes may be the result of a stress response toward a negative stimulus and that, as is currently practiced within marine mammal facilities, these situations should be minimized.…”

The Click Production of Captive Yangtze Finless Porpoises (Neophocaena asiaeorientalis asiaorientalis) Is Influenced by Social and Environmental Factors

“…Here, social events were group separations and reunions, and it seems that Yangtze finless porpoises did not change their click production much following these events. Pool cleaning, which elicits changes in behavior in this group of Yangtze finless porpoises [85][86][87], did not significantly influence their click production either. Noise and pool cleaning can represent stressful stimuli, noise being an acoustic one, while pool cleaning involves the presence of moving objects/humans in the water.…”

“…It seems that the relationship between click production and emotional state can be ambiguous, and hard to interpret on its own. For instance, click density is particularly high when porpoises are feeding, which can be seen as a positive situation, but it is also very high when animals are socially separated, which is probably experienced as a negative situation by these porpoises [85][86][87]. Noting the context when collecting data is crucial to avoid misinterpretations.…”

Increasing the Awareness of Animal Welfare Science in Marine Mammal Conservation: Addressing Language, Translation and Reception Issues

“…Indeed, this bias was demonstrated by the fact that 26.4% (n = 79) of marine mammal welfare articles from the literature review focused on captive animals. Studies on marine mammal welfare in captivity have been increasing over the last 10 years [77,78], and using dolphins as an example, there is now existing research on positive welfare indicators [79][80][81][82][83][84], negative welfare indicators [82,[85][86][87], and a comprehensive assessment framework [88]. Physiological and health-related welfare parameters such as stress hormones [86,89,90], blood profiles [91,92], and pulmonary function [93] have also been examined in captive animals.…”