Behavioral responses of two species of dolphins to novel video footage: An exploration of sex differences.

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.

Evaluating Atlantic bottlenose dolphin (Tursiops truncatus) leukocyte differential counts comparing the CellaVision DM96 and the manual method.

BACKGROUND: The leukocyte differential count is an excellent diagnostic tool; however, the manual differential count has several drawbacks, especially for nontraditional species. Automated cell analyzers commonly used in veterinary practices require species-specific validation for use in nondomestic species other than dogs and cats. OBJECTIVES: The purpose of this study was to examine the potential of the CellaVision DM96 (DM96), an automated image analysis system, as a rapid and accurate method for providing a WBC differential count in comparison to the manual WBC differential count in bottlenose dolphins. METHODS: Ten fresh, EDTA anticoagulated blood samples were collected, blood smears were made and stained, and the differential WBC counts were performed on the DM96 and compared with manual differential WBC counts. Agreement, means, and errors were compared between the methods. RESULTS: There was good agreement between the DM96 and manual differential WBC counts for neutrophils; however, there was significant variation when comparing lymphocyte, monocyte, and eosinophil counts. No basophils were seen by any method. CONCLUSIONS: Despite a small sample size, the DM96 appeared to provide a viable alternative for automated neutrophil counting in blood of bottlenose dolphins. Whether the counts are comparable in animals with highly pathologic differential counts must be addressed in follow-up studies, preferably with more study animals.

AUDITORY EVOKED POTENTIALS AND BEHAVIORAL CONSIDERATIONS WITH HEARING LOSS IN SMALL CETACEANS: APPLICATION AS A STANDARD DIAGNOSTIC TEST IN HEALTH ASSESSMENT.

The primary sense in odontocetes is hearing and a large portion of the odontocete brain is devoted to the auditory processing of echolocation signals. Hearing deficits in odontocetes potentially compromise the ability to forage, navigate, socialize, and evade predators. This presents a challenge to survival and reproduction in wild odontocetes and can affect the general welfare of odontocetes under human care. Currently, little empirical information on how odontocete behavior is affected by hearing loss exists. This study investigated hearing deficits in several species of stranded dolphins and age-related hearing deficits in dolphins kept under human care through auditory evoked potential (AEP) testing and evaluated whether individual behavior correlated with hearing impairment. Behavioral questionnaires for participating animals were completed by individuals with extensive knowledge of the animals' history and behavior. A chi-square analysis determined whether animals with hearing impairment demonstrated behaviors that differed significantly from those considered normal. All tested individuals under human care over 35 years of age had some degree of hearing loss, as did a large percentage of previously stranded animals. Individuals with hearing loss exhibited a range of behavioral changes, including delays in learning new behaviors, accepting novel enrichment, and habituating to new environments. Some individuals with profound hearing loss also displayed a change in vocalization rate in various situations. Findings within previously stranded animals suggest AEP studies should be conducted in all stranded individuals entering rehabilitation. It is further recommended that dolphins living under human care undergo hearing tests as part of their normal health assessments, with emphasis on aging individuals and animals that exhibit delayed learning, respond poorly to audible cues, or show atypical vocalization behavior.

Acoustic behavior associated with cooperative task success in bottlenose dolphins (Tursiops truncatus).

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).

Can bottlenose dolphins (Tursiops truncatus) cooperate when solving a novel task?

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.