The past several decades have witnessed significant improvement in the physical welfare of marine mammals in zoos and aquariums. Over that same time period, research has revealed complex cognitive ...abilities in at least some of these species, yet there has been comparatively little attention paid to addressing their cognitive welfare per se. Studies primarily conducted with terrestrial animals have suggested that providing appropriate cognitive challenges in managed care settings can improve animal well-being. As a step toward facilitating this practice with marine mammals, this paper discusses factors relevant for creating appropriate cognitive challenges, outlines the three major categories of cognitive challenge that have been utilized with marine mammals, along with the logistical pros and cons of each, and calls on organizations that care for marine mammals to cultivate a bias for action with respect to providing cognitive care.
Numerous studies have demonstrated the negative effects of impoverished environments versus the positive effects of enriched environments on animals’ cognitive and neural functioning. Recently, a ...hypothesis was raised suggesting that conditions for dolphins in zoological facilities may be inherently impoverished, and thus lead to neural and cognitive deficits. This review directly examines that hypothesis in light of the existing scientific literature relevant to dolphin welfare in zoological facilities. Specifically, it examines how dolphins are housed in modern zoological facilities, where the characteristics of such housing fall on the continuum of impoverished-to-enriched environments, and the extent to which dolphins show behavioral evidence characteristic of living in impoverished environments. The results of this analysis show that contrary to the original hypothesis, modern zoological facilities do not inherently, or even typically, house dolphins in impoverished conditions. However, it also notes that there is variation in animal welfare across different zoological facilities, and that “not impoverished” would be a particularly low bar to set as an animal welfare standard. To optimize cognitive well-being, strategies for providing additional cognitive challenges for dolphins in zoological facilities are suggested.
Cooperation experiments have long been used to explore the cognition underlying animals' coordination towards a shared goal. While the ability to understand the need for a partner in a cooperative ...task has been demonstrated in a number of species, there has been far less focus on cooperation experiments that address the role of communication. In humans, cooperative efforts can be enhanced by physical synchrony, and coordination problems can be solved using spoken language. Indeed, human children adapt to complex coordination problems by communicating with vocal signals. Here, we investigate whether bottlenose dolphins can use vocal signals to coordinate their behaviour in a cooperative button-pressing task. The two dolphin dyads used in this study were significantly more likely to cooperate successfully when they used whistles prior to pressing their buttons, with whistling leading to shorter button press intervals and more successful trials. Whistle timing was important as the dolphins were significantly more likely to succeed if they pushed their buttons together after the last whistle, rather than pushing independently of whistle production. Bottlenose dolphins are well known for cooperating extensively in the wild, and while it remains to be seen how wild dolphins use communication to coordinate cooperation, our results reveal that at least some dolphins are capable of using vocal signals to facilitate the successful execution of coordinated, cooperative actions.
In cases where social animals must be temporarily housed alone, environmental enrichment is particularly important. Providing animals with manipulable objects (“toys”) is a common form of ...environmental enrichment, but its effectiveness can be limited by animal disinterest or habituation. The current study examined whether caregiver interaction could increase the effectiveness of object-based enrichment for a quarantined bottlenose dolphin (Tursiops truncatus). Behavioral observations were conducted after a training session, after a trainer toy play session, and between interactive sessions. The results showed that the dolphin floated in place less and played with toys more after interacting with a caregiver than he did at times further removed from caregiver interaction. He was also more likely to play with the same toys that the trainer had played with, showing effects of stimulus enhancement and/or social referencing. Although this study is, of necessity, based on a single animal of a single species, these findings suggest that interacting with a caregiver can enhance the efficacy of object-based environmental enrichment for isolated animals.
The ability to mentally represent the movement of hidden objects (i.e., invisible displacement) is of theoretical importance due to its generally accepted status as an indicator of the development of ...a powerful type of representational capacity in human children. Over the past few decades, the understanding of invisible displacement has been claimed for a variety of animal species as well. However, a careful review of these studies finds that: (a) many were not properly blinded, (b) many did not properly control for lower-level associative strategies, and (c) success on simplified versions of the tasks can be explained by a simple attentional mechanism rather than by conceptual understanding. Indeed, when lower-level factors are controlled, evidence of understanding invisible displacement remains only for great apes.
Survival rates and life expectancies are commonly agreed upon indicators of well‐being for animals in zoological facilities, but even the most recent survival statistics for bottlenose dolphins ...(Tursiops truncatus) in marine mammal parks and aquariums use data that are now more than 25 yr old. The current study provides a comprehensive assessment of life expectancy and survival rates for bottlenose dolphins in U.S. zoological facilities from 1974 to 2012, utilizing three different analyses (annual survival rate, age‐at‐death, and Kaplan‐Meier), examining historical trends, and comparing to comparable data from wild populations. Both survival rate and life expectancy for dolphins in zoological facilities increased significantly over the past few decades, with a modern ASR of 0.972, and mean and median life expectancies calculated via Kaplan‐Meier of 28.2 and 29.2 yr, respectively. Survival rates and life expectancies for dolphins in U.S. zoological facilities today are at least as high as those for the wild dolphin populations for which there are comparable data.
Reliable scientific knowledge is crucial for informing legislative, regulatory, and policy decisions in a variety of areas. To that end, scientific reviews of topical issues can be invaluable tools ...for informing productive discourse and decision-making, assuming these reviews represent the target body of scientific knowledge as completely, accurately, and objectively as possible. Unfortunately, not all reviews live up to this standard. As a case in point, Marino et al.’s review regarding the welfare of killer whales in captivity contains methodological flaws and misrepresentations of the scientific literature, including problematic referencing, overinterpretation of the data, misleading word choice, and biased argumentation. These errors and misrepresentations undermine the authors’ conclusions and make it impossible to determine the true state of knowledge of the relevant issues. To achieve the goal of properly informing public discourse and policy on this and other issues, it is imperative that scientists and science communicators strive for higher standards of analysis, argumentation, and objectivity, in order to clearly communicate what is known, what is not known, what conclusions are supported by the data, and where we are lacking the data necessary to draw reliable conclusions.
Two recent papers by Kuczaj et al. (Anim Cognit 18:543–550,
2015
) and Eskelinen et al. (Anim Cognit 19:789–797,
2016
) claim to have demonstrated that (i) bottlenose dolphins (
Tursiops truncatus
) ...cooperated to solve a novel task and (ii) vocal signals were important for coordinating these cooperative efforts. Although it is likely that bottlenose dolphins may share communicative signals in order to achieve a common goal, we suggest that this has not been demonstrated in the aforementioned studies. Here, we discuss the two main problems that preclude any definitive conclusions being drawn on cooperative task success and vocal communication from these studies. The first lies in the experimental design. The ‘cooperative task’, involving an apparatus that requires two dolphins to pull in opposite directions in order to achieve a food reward, is not conducive to cooperation, but could instead reflect a competitive ‘tug-of-war’. It is therefore of questionable use in distinguishing competitive from cooperative interactions. Second, the suggestion that the occurrence of burst-pulsed signals in this task was indicative of cooperation is disputable, as (i) this study could not determine which dolphins were actually producing the signals and (ii) this sound type is more commonly associated with aggressive signalling in dolphins. We commend the authors for investigating this exciting and topical area in animal communication and cognition, but the question of whether dolphins cooperate and communicate to solve a cooperative task remains as yet unanswered.
Object permanence, the ability to mentally represent and reason about objects that have disappeared from view, is a fundamental cognitive skill that has been extensively studied in human infants and ...terrestrial animals, but not in marine animals. A series of four experiments examined this ability in bottlenose dolphins (Tursiops truncatus). After being trained on a “find the object” game, dolphins were tested on visible and invisible displacement tasks, and transpositions. In Experiments 1 and 2, dolphins succeeded at visible displacements, but not at invisible displacements or transpositions. Experiment 3 showed that they were able to pass an invisible displacement task in which a person's hand rather than a container was used as the displacement device. However, follow-up controls suggested they did so by learning local rules rather than via a true representation of the movement of hidden objects. Experiment 4 demonstrated that the dolphins did not rely on such local rules to pass visible displacement tasks. Thus, like many terrestrial animals, dolphins are able to succeed on visible displacement tasks, but seem unable to succeed on tasks requiring the tracking of hidden objects.
Jaakkola (2014) argued that because the majority of studies of animals' understanding of invisible displacement did not adequately control for the use of alternative lower-level strategies, clear and ...solid evidence for a conceptual understanding of invisible displacement existed only for great apes. Pepperberg (2015) takes issue with this conclusion with respect to Grey parrots. While I agree that olfactory and social cueing may not be issues of concern for parrots, I reiterate the need for a study that adequately controls for associative learning before we can confidently claim that parrots understand invisible displacement.
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