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Open Access Publications from the University of California


The International Journal of Comparative Psychology is sponsored by the International Society for Comparative Psychology. It is a peer-reviewed open-access digital journal that publishes studies on the evolution and development of behavior in all animal species. It accepts research articles and reviews, letters and audiovisual submissions.

Volume 23, Issue 4, 2010

Special Issue

The Synergy of Laboratory and Field Studies of Dolphin Behavior and Cognition

Dolphin behavior and cognition have been studied in both the laboratory and the wild. Laboratory studies provide high levels of control over experimental variables and the opportunity to investigate the cognitive mechanisms of behavior. However, laboratory studies are typically limited to a few subjects. Field studies have the benefit of examining behavior and social interactions among large numbers of individuals. They can reveal how cognitive abilities are expressed naturally, and can provide external validity for observations in the laboratory. However, there is typically less controlover experimental variables in field studies than in the laboratory. Thus, a synergistic relationship has emerged between laboratory and field studies of dolphin behavior and cognition with each contributing information and ideas to the other that can lead to new questions and insights. This relationship is demonstrated using four issues: a) the types of percepts and mental representations dolphins can form through echolocation; b) the complexity of relationships that dolphins can understand; c) the dolphin's competency in symbolic referential communication; and d) the dolphin's ability to manage joint attention through pointing and gazing.

Overlap between Information Gained from Complementary and Comparative Studies of Captive and Wild Dolphins

Dolphin behavior has been observed in both captive and wild settings for years. Comparisons of captive and wild aquatic mammals have proven difficult because of limitations placed on observers in both arenas; still research conducted in each setting provides details often unavailable from the other environment. For example, internal body states (e.g., hormone levels) that might effect the expression of certain behaviors cannot readily be measured from wild dolphins; however, they can be routinely documented during husbandry behaviors. Conversely, detailed documentation of dolphin travel patterns is more readily available from long-term studies of wild dolphins; and while travel patterns are not applicable for study from captive individuals, observation of movement patterns within a pool can be examined to provide insight into an individual’s behavior or inter-individual interactions. Long-term observations from three captive and three wild dolphins study populations are presented comparatively to illustrate how work on groups in each setting can complement one another. Additionally, data from a survey of trainers (50 surveys distributed with 17 completed surveys received) suggests that dolphin trainers interpreted several behaviors in ways that were consistent with observations of wild dolphins. For example, tail slapping was reported mainly as irritation(45.5%) or frustration (22.7%), but was also suggested to occur in play (31.8%). Pectoral fin rubs were used in appeasement (15.4%), comfort (7.7%), and affection (26.9%) more so than in sexual(7.7%) contexts or not at all (7.7%). Jaw claps, hitting, biting, chasing and ramming were observed in aggressive contexts in both captivity and the wild. More significantly, there were no consistent differences between wild and captive dolphins reported by surveyed trainers. The author’s ongoing research program merges advantages from both environments to facilitate a more thorough understanding of dolphin communication and society.

Observing Cognitive Complexity in Primates and Cetaceans

This paper on cognitive complexity in primates and cetaceans is a review of studies that use onlyobservational methods. These studies include descriptive accounts, both qualitative and quantitative,of behavior-in-context in naturally-occurring and quasi-experimental settings, especially involvingthe micro-analysis of video. To unify this piecemeal but burgeoning literature, “cognition” is taken asembodied, largely visible, and distributed across physical and social environments. Its study involvesdocumenting the adaptation of behavior to changing conditions, especially in ontogeny, tool-use, andsocial discourse. The studies selected for this review focus on the cognitive complexity that isapparent in the versatility, the hierarchical organization, and the long-term patterning of suchbehavioral adaptations. Versatility is seen, for example, in the substitution of different acts or objectsinto established routines, in the size and flexibility of action repertoires that enable variablyconfigured and sequenced performances, and in the marked occurrence of individual differences.Hierarchical organization is seen in the substitution or iteration of a subroutine that fails to disrupt itslarger routine, in the simultaneous embedding of one social interaction within the frame of another(as in “social tool” use), and in the insertion of a novel or borrowed subroutine as a tactical response,especially one that temporarily redirects an animal‟s trajectory. The complexity apparent in long-termpatterning includes tracking and making selective use of multiple histories (e.g., concerning kinship,rank, etc.) whose predictions and tactics may vary, responding to “market” values that change withecological and social factors, and exploiting traditions of practice which provide social and materialresources that shape engagement and learning. While this literature includes far more primate thancetacean examples, the primate work offers helpful suggestions for settings, issues, and techniquesthat could be adapted to the sensori-motor, ecological, and social constraints on cetacean cognition.The array of observations reviewed illustrate the utility across species of scoring such parameters asdisplays of attention in multiple modalities, abrupt trajectory changes, the complementarity andcontingency of actions, and the resiliency of sequences, to help identify the media that matter in agiven cognitive ecology. Systematic micro-analyses, in conjunction with long-term relational datathat track changes in affordances and coordination, make such observational approaches a viable andvaluable addition to the study of comparative cognition.

Studying Dolphin Behavior in a Semi-Natural Marine Enclosure: Couldn't we do it all in the Wild?

The study of marine mammals in the wild is faced with major difficulties: encounter frequency and duration are limited, individual identification is difficult, social behaviors occur mostly in murky or deep water, the ability to assign vocalizations to individuals is usually very limited, sea conditions are not always suitable for research, and the design of controlled experiments is virtually impossible. In contrast, research in captivity poses different methodological obstacles due to confined space, artificial and sometimes poor environments, forced social structure, small sample sizes, subjects that are not always good representatives of wild populations etc., all provide constant challenge to scientists. This paper reviews some of the studies on Black Sea bottlenose dolphins (Tursiopstruncatus ponticus) conducted during the 15 years since the establishment of the International Laboratory for Dolphin Behaviour Research (ILDBR) located at the semi-natural Dolphin-Reef (Eilat, Israel) tourist facility. We describe how this site overcomes many of the problems that characterize captivity sites, and how our research gains important insight into dolphin behavior, which is difficult to obtain – if at all – in the study of wild populations. We conclude that studies ofcaptive and wild dolphins can complement each other for a better understanding of dolphin behavior.

Recent Studies on Captive Cetaceans in Japan: Working in Tandem with Studies on Cetaceans in the Wild

Recent technological advances have allowed researchers to acquire a vast amount of information on wild cetaceans, much of which had previously been inaccessible. However, despite these new technologies, existing studies on cetaceans in captivity remain valuable. In this article, we review the recent research conducted on captive cetaceans in Japan to show their importance. We indexed the existing studies regarding behavior (resting behavior, vocal development, social behavior, and behavior differences between species), comparative cognition (echolocation ability), stress reduction,and reproductive physiology. The resulting data, as well as an understanding of the techniques used to obtain these data, will help improve the condition of cetaceans (especially endangered species) kept in captivity and fill in the gaps of studies done on cetaceans in the wild.

Can Dolphins Plan their Behavior?

The ability to plan one’s behavior in novel and appropriate ways when confronted with new problemshas been found in members of relatively few species. This ability provides significant evolutionaryadvantages in that the planner can mentally assess possible solutions prior to implementing one ofthem, and so need not risk life and limb by muddling though possible solutions to problems via trialand error learning. Although there are instances of wild dolphin behavior that suggest planning, it isdifficult to determine if such behaviors were the result of planning, trial and error learning, or evensome form of serendipitous discovery. Investigations of problem solving in bottlenose dolphins livingin zoological settings can better assess the actual causes of apparent planning, and such controlledstudies have demonstrated that dolphins can plan their behaviors in novel contexts. These settingsfacilitate the assessment of processes that underlie behaviors of interest, while observations from thewild provide invaluable information about apparent planning behavior in various contexts.Integrating findings from both settings is necessary if we hope to fully understand the dolphincapacity for planning.

Blindfolded Imitation in a Bottlenose Dolphin (Tursiops truncatus)

This study investigated the ability of a bottlenose dolphin to adapt a previously learned "do-as-I-do"procedure to copy behaviors of another dolphin while blindfolded (i.e., wearing eyecups). In Experiment 1, the dolphin was able to copy both vocal and motor behaviors, whether blindfolded or sighted. Hydrophone recordings showed that he echolocated during many of the motor behaviors while blindfolded. In Experiment 2, blindfolded human trainers were able to identify the same model behaviors on the basis of their characteristic sounds. While it thus remains unclear whether the dolphin recognized the motor behaviors via echolocation or via their characteristic sounds, this is the first demonstration of such flexibility in using a new perceptual route to motor imitation in a nonhuman animal.

The Occurrence and Context of S-Posture Display by Captive Belugas (Delphinapterus leucas

The “S-posture” is described in the cetacean literature as a radical flexure of the body which presents an atypically vertical visual signal. It has most commonly been associated with agonistic high arousal contexts, and often includes simultaneous acoustic outbursts. Its dynamic qualities – an abrupt retardation of forward motion, sweeping flexure of the flukes, and sustained arch – suggest its saliency to the cetacean’s motion-sensitive visual system. This study reports on the occurrence of S-postures in four captive beluga whales (Delphinapterus leucas) held at SeaWorld San Diego. During approximately 27 hours of video data, a total of 174 S-postures were displayed by three out of four belugas. None of the S-postures observed co-occurred with another visual display (i.e., bubbleclouds, open mouth, jaw clap), while only 8% were observed to have co-occurred with an acoustic production by the whales present. The proportion of S-postures displayed by each subject was analyzed for differences in the following contexts: the state (open/closed) of a rear gate leading to a separate pool, the presence of cohabitant harbor seals (Phoca vitulina), and the total number ofbelugas in the same pool.

Play in Wild and Captive Cetaceans

Although play behavior is difficult to define, it has been abundantly documented in the cetaceanliterature. Play behavior is prevalent among the various taxa and is exhibited by individuals of all ageclasses. However, it is often difficult to follow individuals, observe underwater behavior, and obtainmultiple sightings of individuals when investigating free-ranging populations. Captive studies allowfor the systematic manipulation of variables and the collection of detailed data with regard toindividuals, age, and gender by being able to observe behavior both at the surface and underwater.Pooling information from both wild and captive studies of play allows for more robust theories,conclusions and understanding. In this paper, we provide a review of play behavior in both wild andcaptive cetacean populations as a first step toward a more complete understanding of the significanceof cetacean play.

Ovarian Follicular Dynamics During the Luteinizing Hormone Surge in the Bottlenose Dolphin (Tursiops truncatus)

Characterizing the relationship between ovarian follicular dynamics and the luteinizing hormone (LH) surge in the bottlenose dolphin (Tursiops truncatus) requires detailed daily monitoring due to the transitory nature of LH and ovulation. Utilizing conditioned dolphins and non-invasive sampling techniques, such as urine collection and trans-abdominal ultrasound exams, provides the means to accurately monitor these fleeting processes. Urine samples and ultrasound exams used in this study were originally performed for the purposes of artificial insemination and controlled natural breeding. The LH surge was identified by a rapid immunochromatographic assay (ICG), and real-time B-modetrans-abdominal ultrasound imaging was used to identify pre-ovulatory follicles (POF). Increases in urinary progesterone levels along with the disappearance of the POF verified ovulation. This studyfound that POF diameters during the LH surge were 1.942 +/- 0.098 cm (n = 9), and time to disappearance of the POF from the last recorded LH peak sample was 37.475 +/- 12.346 h (n = 6). Peak LH surge levels, based on samples collected 2 to 4 times daily, lasted 6.050 +/- 1.332 h (n = 6). Data suggests that bottlenose dolphins, like many other mammals, have brief ovulatory LH surges followed by ovulation within 48 hours.

Non-invasive Multidisciplinary Approach to the Study of Reproduction and Calf Development in Bottlenose Dolphin (Tursiops truncatus): The Rimini Delfinario Experience

Reproduction is a fundamental biological process that occurs only when all other vital needs are satisfied. In cetaceans reproduction takes place completely in water. From courtship and mating tocalf weaning, every step of the reproductive process occurs under the water’s surface. This complicates data acquisition in wild populations, making captive observations a useful complement to wild studies. By allowing close examination of phenomena, studies in captive environments are able to collect long-term data on known subjects, and sample, in detail, complete behavioural sequences while monitoring physiological or acoustic patterns. Studies of reproduction in bottlenose dolphins (Tursiops truncatus) were initiated at Rimini Delfinario (Italy) in 1995. Four bottlenose dolphin births (in 1995, 1997, 2003 and 2007) have occurred since the start of this research. Due to evidence suggesting that mother and calf associations are closest in the first year of the calf’s life, mothers and calves were studied from birth to the end of the first year. Beginning in 1997, studies encompassed the behaviour and physiology of dolphin mothers during gestation. Here, we report results of interdisciplinary studies of reproductive processes in bottlenose dolphins, including aspects of behaviour, physiology, endocrinology, and acoustics. In an effort to reduce the potential for bias brought about by invasive sampling, we investigated methods of sampling expired air from the dolphin’s blow hole as a means of monitoring steroid hormone levels. In summary, our research combines an interdisciplinary network with specialized professional alliances and offers a potentially crucial approach to the biological aspects of reproduction. At the same time, research findings presented here aim to help bridge the gap existing between captive and wild studies in favor of acommon aim of conservation biology.

Advances in Husbandry Training in Marine Mammal Care Programs

The aim of this paper is to illustrate how the training of marine mammals has facilitated improved marine mammal husbandry practices. The marine mammal community has seen many changes, refinements and improvements in animal care programs since the first marine mammals were brought in captivity in the early 19th century. Cross disciplinary fields such as veterinarian science, psychology, physiology and conservation biology have advanced the knowledge and care of the different species of cetaceans, pinnipeds, sirenians and otters and brought marine mammal care programs to the standard they are today. In this paper a broad overview is given of the main advances in husbandry training in marine mammal care programs worldwide.

Marine Mammals Enact Individual Worlds

Scientific literature describes the various ways that we perceive animals and their contribution to our humanization. Our understanding of “animality” is changing, corresponding to an ever-increasing general knowledge of animals. Scientific studies provide objective descriptions of the complexity of animal worlds. The present article discusses recent findings on socio-spatiality, social cognition, and self-recognition in various marine mammal species, as well as the relevance and coherence of theories used to explain them. In a constructivist ethological approach, animals are not considered to be mere living organisms or objects, but rather, subjects. All animals use their senses to create relationships with their physical and social environments. Through their perceptions and actions, they give meaning to their surroundings; they enact individual and specific worlds, known as umwelts.The human-animal relationship is an inter subjectivity. Examples from studies of bottlenose dolphins (Tursiops truncatus) and killer whales (Orcinus orca) can be used to hypothesize the existence of a context-dependent situated self. Finally, animal welfare/well-being and the effectiveness of environmental enrichment programs can be re-evaluated in the context of this theoretical framework. In sum, no objective world exists; rather, we propose the existence of multiple context-dependent cognitive and subjective umwelts. The present article is the first to consider marine mammals with this perspective.

Learning about Manatees: A Collaborative Program between New College of Florida and Mote Marine Laboratory to Conduct Laboratory Research for Manatee Conservation

Research with captive manatees initiated as part of a New College of Florida class project at MoteMarine Laboratory has yielded a wide range of research with substantive implications formanagement and conservation. Our training program directly supported investigations of bloodchemistry, immune function, stress-related physiology, respiration, thermoregulation, and behavioralecology. Our investigations of sensory processes included studies of visual acuity, color vision,passive and active touch, auditory frequency detection thresholds, auditory temporal processing rates,hearing in noise, and sound localization. Undergraduate and graduate students involved in thisprogram have been successfully mentored in sensory processes, animal behavior, and conservation.Further validation of the educational benefits of studying captive manatees awaits formal research onattitude, behavior change, and public policy related to protecting manatees and other marinemammals in natural settings.