Diana Reiss

Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence

The ability to recognize oneself in a mirror is an exceedingly rare capacity in the animal kingdom. To date, only humans and great apes have shown convincing evidence of mirror self-recognition. Two dolphins were exposed to reflective surfaces, and both demonstrated responses consistent with the use of the mirror to investigate marked parts of the body. This ability to use a mirror to inspect parts of the body is a striking example of evolutionary convergence with great apes and humans.

Insightful problem solving in an Asian elephant.

The “aha” moment or the sudden arrival of the solution to a problem is a common human experience. Spontaneous problem solving without evident trial and error behavior in humans and other animals has been referred to as insight. Surprisingly, elephants, thought to be highly intelligent, have failed to exhibit insightful problem solving in previous cognitive studies. We tested whether three Asian elephants (Elephas maximus) would use sticks or other objects to obtain food items placed out-of-reach and overhead. Without prior trial and error behavior, a 7-year-old male Asian elephant showed spontaneous problem solving by moving a large plastic cube, on which he then stood, to acquire the food. In further testing he showed behavioral flexibility, using this technique to reach other items and retrieving the cube from various locations to use as a tool to acquire food. In the cubes absence, he generalized this tool utilization technique to other objects and, when given smaller objects, stacked them in an attempt to reach the food. The elephants overall behavior was consistent with the definition of insightful problem solving. Previous failures to demonstrate this ability in elephants may have resulted not from a lack of cognitive ability but from the presentation of tasks requiring trunk-held sticks as potential tools, thereby interfering with the trunks use as a sensory organ to locate the targeted food.

A claim in search of evidence: reply to Manger's thermogenesis hypothesis of cetacean brain structure

In a recent publication in Biological Reviews, Manger (2006) made the controversial claim that the large brains of cetaceans evolved to generate heat during oceanic cooling in the Oligocene epoch and not, as is the currently accepted view, as a basis for an increase in cognitive or information‐processing capabilities in response to ecological or social pressures. Manger further argued that dolphins and other cetaceans are considerably less intelligent than generally thought. In this review we challenge Manger’s arguments and provide abundant evidence that modern cetacean brains are large in order to support complex cognitive abilities driven by social and ecological forces.

Bubble Ring Play of Bottlenose Dolphins (Tursiops truncatus): Implications for Cognition

Research on the cognitive capacities of dolphins and other cetaceans (whales and porpoises) has importance for the study of comparative cognition, particularly with other large-brained social mammals, such as primates. One of the areas in which cetaceans can be compared with primates is that of object manipulation and physical causality, for which there is an abundant body of literature in primates. The authors supplemented qualitative observations with statistical methods to examine playful bouts of underwater bubble ring production and manipulation in 4 juvenile male captive bottlenose dolphins (Tursiops truncatus). The results are consistent with the hypothesis that dolphins monitor the quality of their bubble rings and anticipate their actions during bubble ring play.

Self‐recognition in the Asian elephant and future directions for cognitive research with elephants in zoological settings

The field of animal cognition has grown steadily for nearly four decades, but the primary focus has centered on easily kept lab animals of varying cognitive capacity, including rodents, birds and primates. Elephants (animals not easily kept in a laboratory) are generally thought of as highly social, cooperative, intelligent animals, yet few studies-with the exception of long-term behavioral field studies-have been conducted to directly support this assumption. In fact, there has been remarkably little cognitive research conducted on Asian (Elephas maximus) or African (Loxodonta africana or L. cyclotis) elephants. Here, we discuss the opportunity and rationale for conducting such research on elephants in zoological facilities, and review some of the recent developments in the field of elephant cognition, including our recent study on mirror self-recognition in E. maximus.

Dolphins in popular literature and media

This review of how dolphins are portrayed in popular media (including literature, film, television, and music) reveals four themes that may influence public acceptance of current scientific research into dolphin cognition. These themes are: (a) dolphin as peer to humans, of equal intelligence or at least capable of communicating with or helping humans; (b) the dolphin as the representation of a romantic notion of ideal freedom in nature, embodying principles of peace, harmony or love; (c) the dolphin as a naive, innocent being that is subordinate and in need of human protection; and (d) the dolphin as superior to humans, potentially affiliating with a higher power or intelligence. This review revealed that the use of dolphins in humor reinforced or lampooned the four identified themes, indicating a common acceptance of these themes. The paper concludes with a discussion of the importance of considering popular narratives in the presentation of scientific research results.

The influence of feeding, enrichment, and seasonal context on the behavior of Pacific Walruses (Odobenus rosmarus divergens)

Though some research exists concerning general behavior and activity patterns of Walruses in zoos or aquariums, less is known about how these patterns change in response to various environmental and temporal contexts. This study presents two studies assessing behavioral changes in relation to feeding period, object enrichment (OE), and season in a social group of four Pacific Walruses at the New York Aquarium. Study 1 examined behavior in relation to feeding context (nonfeed, prefeed, postfeed); data were collected over a three-week period, resulting in 47 observation sessions for each feeding context. Study 2 examined behavior in relation to OE and season; data were collected in two phases resulting in 12 enrichment and 9 no-enrichment (NE) observation sessions (Phase 1), and 21 enrichment and 18 NE observation sessions (Phase 2). Study 1 showed that after feeding, oral behavior increased while social behavior and total swim frequency decreased. In Study 2, both swim frequency and social behavior were found to interact with OE and phase, while oral behavior remained constant across all conditions. As in the wild, both studies found all animals to be swimming the majority of the time. Though every animal spent much of its swim time engaged in an Individual Swimming Pattern (ISP), both studies showed that the proportion of ISP (in relation to total time swimming) remained stable across all contexts, suggesting a potential functional role of the ISPs. These results are discussed in light of the ongoing debate over the role of stereotypies in welfare assessment.

A Veterinary and Behavioral Analysis of Dolphin Killing Methods Currently Used in the “Drive Hunt” in Taiji, Japan

Annually in Japanese waters, small cetaceans are killed in “drive hunts” with quotas set by the government of Japan. The Taiji Fishing Cooperative in Japan has published the details of a new killing method that involves cutting (transecting) the spinal cord and purports to reduce time to death. The method involves the repeated insertion of a metal rod followed by the plugging of the wound to prevent blood loss into the water. To date, a paucity of data exists regarding these methods utilized in the drive hunts. Our veterinary and behavioral analysis of video documentation of this method indicates that it does not immediately lead to death and that the time to death data provided in the description of the method, based on termination of breathing and movement, is not supported by the available video data. The method employed causes damage to the vertebral blood vessels and the vascular rete from insertion of the rod that will lead to significant hemorrhage, but this alone would not produce a rapid death in a large mammal of this type. The method induces paraplegia (paralysis of the body) and death through trauma and gradual blood loss. This killing method does not conform to the recognized requirement for “immediate insensibility” and would not be tolerated or permitted in any regulated slaughterhouse process in the developed world.

Acoustic and behavioral repertoires of the hippopotamus (Hippopotamus amphibius)a)

This study describes the acoustic and behavioral repertoires of the common hippopotamus (Hippopotamus amphibius). Simultaneous audio and video recordings were collected of male and female hippos at Disneys Animal Kingdom(®). Visual inspection of spectrograms resulted in classifying signals into three main categories (burst of air, tonal, and pulsed) produced in-air, underwater, or simultaneously in both mediums. Of the total acoustic signals, most were produced underwater (80%), and the majority of the total signals were tonal (54%). Using multivariate analysis of the acoustic parameters, 11 signal types were described and differentiated. In the burst of air category, chuffs and snorts were distinguished by minimum and peak frequency, and bubble displays were described. In the tonal category, grunts, groans, screams, and whines were distinguished by several frequency measures (e.g., minimum, maximum, fundamental, peak frequency). Wheeze honks were tonal signals that often involved a chorus of overlapping calls. In the pulsed category, click trains, croaks, and growls were distinguished by frequency and duration. Video analysis demonstrated that chuffs, groans, and whines were associated with submissive contexts, while snorts, grunts, and growls were associated with dominance contexts. These results provide further information about the acoustic signals and concurrent behavior of hippos.

Precocious development of self-awareness in dolphins

Mirror-self recognition (MSR) is a behavioral indicator of self-awareness in young children and only a few other species, including the great apes, dolphins, elephants and magpies. The emergence of self-awareness in children typically occurs during the second year and has been correlated with sensorimotor development and growing social and self-awareness. Comparative studies of MSR in chimpanzees report that the onset of this ability occurs between 2 years 4 months and 3 years 9 months of age. Studies of wild and captive bottlenose dolphins (Tursiops truncatus) have reported precocious sensorimotor and social awareness during the first weeks of life, but no comparative MSR research has been conducted with this species. We exposed two young bottlenose dolphins to an underwater mirror and analyzed video recordings of their behavioral responses over a 3-year period. Here we report that both dolphins exhibited MSR, indicated by self-directed behavior at the mirror, at ages earlier than generally reported for children and at ages much earlier than reported for chimpanzees. The early onset of MSR in young dolphins occurs in parallel with their advanced sensorimotor development, complex and reciprocal social interactions, and growing social awareness. Both dolphins passed subsequent mark tests at ages comparable with children. Thus, our findings indicate that dolphins exhibit self-awareness at a mirror at a younger age than previously reported for children or other species tested.