Application of environmental enrichment, as a means to successfully decrease undesired behaviors (e.g., stereotypic) and improve animal welfare, has been documented in a variety of zoological species. However, a dearth of empirical evidence exists concerning age, sex, and individual differences in response to various types of enrichment tools and activities in Atlantic bottlenose dolphins (Tursiops truncatus). This study involved a comparative assessment of enrichment participation of three resident, bottlenose dolphin populations, over the course of 17 months, with respect to sex and age class (calf, sub-adult, adult). Enrichment sessions were randomly assigned, conducted, and categorically assessed based on participation during seven, broad based enrichment classes (Object, Ingestible, Human, or a combination of the three). Overall, the proportion of participation in enrichment sessions was high (≥ 0.74), with individual differences in participation noted among the three populations. Sessions involving Humans and/or Ingestible items resulted in a significantly higher mean proportion of participation. Subadult and adult males were significantly more likely to participate in enrichment sessions, as well as engage in Human Interaction/Object sessions. Calves participated significantly more than adults or sub-adults across all enrichment classes with no noted differences between males and females. These data can serve as a tool to better understand the intricacies of bottlenose dolphin responses to enrichment in an effort to develop strategic enrichment plans with the goal of improving animal well-being and welfare.

Cooperative behavior has been observed in cetacean species in a variety of situations, including foraging, mate acquisition, play, and epimeletic behavior. However, it has proven difficult to demonstrate cooperative behavior among dolphins in more controlled settings. Dolphins (Tursiops truncatus) in this study were exposed to a task that could most easily be solved if dolphins cooperated. Six dolphins were provided opportunities to solve the task and had to learn to do so without human intervention or training. Two adult males consistently and spontaneously jointly interacted in order to most efficiently open a container that contained fish by pulling on ropes at the ends of the container. Their interaction was viewed as cooperative because each dolphin pulled on their respective ropes in the opposite direction, which resulted in one end of the container opening. The dolphins did not show aggression toward one another while solving the task, and both dolphins consumed the food after the container was opened. They also engaged in synchronous non-aggressive behaviors with the container after the food had been consumed. It is possible that some of the remaining four dolphins would have cooperated, but the two successful dolphins were dominant males and their interest in the apparatus appeared to preclude other animals from participating.

Although many species have proven capable of cooperating to achieve common goals, the role of communication in cooperation has received relatively little attention. Analysis of communication between partners is vital in determining whether actions are truly cooperative rather than serendipitous or learned via trial and error (Chalmeau and Gallo in Behav Process 35:101-111, 1996a. doi: 10.1016/0376-6357(95)00049-6 , Primates 37:39-47, 1996b. doi: 10.1007/BF02382918 ). Wild cetaceans often produce sounds during cooperative foraging, playing, and mating, but the role of these sounds in cooperative events is largely unknown. Here, we investigated acoustic communication between two male bottlenose dolphins while they cooperatively opened a container (Kuczaj et al. in Anim Cogn 18:543-550, 2015b. doi: 10.1007/s10071-014-0822-4 ). Analyses of whistles, burst pulses, and bi-phonations that occurred during four contexts (i.e., no container, no animals interacting with container, one animal interacting with container, and two animals interacting with container) revealed that overall sound production rate significantly increased during container interactions. Sound production rates were also significantly higher during cooperative successes than solo successes, suggesting that the coordination of efforts rather than the apparatus itself was responsible for the phonation increase. The most common sound type during cooperative successes was burst pulse signals, similar to past recordings of cooperative events in bottlenose dolphins (Bastian in Animal sonar systems. Laboratoire de Physiologie Acoustique, Jouy-en Josas, pp 803-873, 1967; Connor and Smolker 1996).

The use of technology in laboratory and zoological settings has provided opportunities for advancement of cognition research as well as cognitive enrichment in a variety of species. Such systems have been successfully created for nonhuman primates and introduced to other anatomically and physiologically diverse species such as bears and tortoises. However, such systems have yet to be used with frequency in aquatic species given the challenge of incorporating accessible technology in such a setting. Herein, we report the successful creation and implementation of a novel manipulatable computerized system with California sea lions (Zalophus californianus) housed in outdoor sea pens. The Enclosure Video Enrichment (EVE) system was created and provided to three adult male sea lions living at the U.S. Navy’s Marine Mammal Program. The interface was modified from those used with other species to accommodate the anatomical and physiological differences of the study subjects. Training procedures were adapted from those successfully used with nonhuman primates to emphasize successive learning approximations. Each of the sea lions introduced to EVE successfully learned to engage with the system at differing rates over the course of a year and a half. While each showed significant differences in interaction style (e.g., number of button presses), all were able to achieve the same criterion for acquisition. This system is the first recorded success in providing a technological means to test cognition in California sea lions through an animal-manipulated interface and has the potential to function as a form of cognitive enrichment in this species.

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.