Founded in 1989, the primary objective of the Roatan Institute for Marine Sciences (RIMS) is the preservation of Roatan’s natural resources through education and research. In the past decade, RIMS has established itself as a dedicated teaching institution. RIMS is visited year-round by students and groups from colleges, universities and high schools from abroad who study tropical marine ecosystems as well as the bottlenose dolphins who reside at Bailey’s Key. Many programs are for academic credit, some are in conjunction with other field research stations, and others are simply introductory courses to the ecology of coral reefs in the Caribbean.
The Roatan Institute for Marine Science is ideally situated for marine study on the northwest coast of Roatan where over 30 miles of fringing and barrier reefs, seagrass beds, mangroves and shoreline are home to an astonishing profusion of life. RIMS is located at Anthony’s Key Resort.
Anthony’s Key Resort
More than 40 years ago, the creators of Anthony’s Key Resort envisioned a small, tropical hide-away that would allow adventurous travelers the opportunity to experience the beauty of Roatan and the Caribbean as nature intended.
Today, the resort still retains an intimacy with its surroundings that is reminiscent of a peaceful island village. Charming, wooden cabanas dot the resort’s palm studded hillside and rim its shimmering lagoon. Reached by a brief boat ride from the resort’s main grounds, the tiny islet that is its namesake features more private cabanas and spectacular ocean vistas. While a favorite pastime among guests is lazing in the cabanas’ hammocks, more active visitors can enjoy various water sports on the key’s small beach.
Back at the resort’s main grounds, the restaurant and bar are perched high on a hillside surrounded by towering coconut palms. There, more sweeping views and fiery sunsets are served up alongside delicious tropical fare. Just steps below at the waters edge are the photo, gift and dive shops, where there is dockage for a fleet of state-of-the art dive boats. A short walk from there takes visitors to the Roatan Museum and Roatan Institute of Marine Sciences, where guests can participate in educational programs and encounters with marine mammals. More inquisitive guests can join trained naturalists across the lagoon on Bailey’s Key to interact with playful dolphins and observe some of the island’s indigenous plants and animals along the key’s nature trail.
Anthony’s Key Resort’s successful blend of nature, comfort and hospitality, continues to draw return visitors and thousands more in search of tranquility and adventure. Click here for more information on Anthony’s Key Resort.
Teeming with colorful marine life, the spectacular reefs around Roatan and near Anthony’s Key Resort are ideally suited for dive novices and experts as well as for snorkellers. All dive sites are just 5 to 30 minutes away by boat ride.
Coral grows thickly along drop-offs that begin in crystalline waters as shallow as 10 feet deep and plunge to the purple depths of the Caribbean.
Squadrons of eagle ray, schools of brightly colored tropical fish, the occasional meandering shark and eel gardens are just a few of the sites that delight divers. Several large wrecks exist not far from the resort and offer unlimited options for interesting and exciting dives.
With water temperatures averaging 80 degrees or better, few currents and visibility ranging from 50 to 100 feet, Roatan provides both deep and shallow diving visitors with colorful, thrilling and comfortable experiences.
RIMS Research Site Overview Video
RIMS Video 2013 from John Anderson on Vimeo.
A Comparative Study of the Behavior and Sounds of Wild and Captive Dolphins
Who: Participants collaborate with Dr. Kathleen Dudzinski, Director of the Dolphin Communication Project.
What: A research program to examine dolphin acoustics, behavior and communication. We conduct surface and underwater observations and passive acoustic recordings of dolphin sounds and behavior.
Where: Roatan, Honduras, in conjunction with the Roatan Institute for Marine Sciences (RIMS). This is an island north of the mainland of Honduras and accessible directly by flight from Miami.
When: Since September 2003, annually. Trips now offered each October, with a field course in Animal Behavior tentatively planned for 2016.
Why: To learn more about dolphin social behavior and signal exchange. To better understand similarities and differences in behavior between captive and wild dolphins.
The sociobiology and ecology of a species plays an important role in its adjustment to the captive environment (Defran & Pryor, 1980; Inglis & Shepherd, 1990): dolphins from coastal, shallow habitats live longer in and are less stressed by captivity when compared with more pelagic, open-ocean species (Defran & Pryor, 1980). Nevertheless, almost no data comparing captive and free-ranging dolphin behavior and sociality have been collected (one exception is Renjun et al., 1994). Detailed observations of social behavior among captive animals (e.g., Tyack, 1986; Gales & Waples, 1993; Nelson & Lien, 1994) and field experiments which examine the social systems of animals (e.g., Cheney & Seyfarth, 1990; Connor, 1990; Norris et al., 1994) have jointly begun to direct progress in social ecology. Comparing data from work on Atlantic spotted dolphins (Dudzinski, unpublished data, 1992 – 1995, 1997 – 2002; Melillo-Sweeting, unpublished data, 2003 – 2014 (Bimini)) and data from work on wild bottlenose dolphins (Takako Iwatani, ICERC Japan, pers. commn., 1995), with detailed observations on the associations and behavioral interactions of bottlenose dolphins at RIMS will provide the first examination and account of dolphin behavior observed primarily underwater from both captive and wild perspectives. This information (even considering the comparison between two different species) will be invaluable in assessing the advantages and disadvantages of the captive environment, will potentially yield new insights to the social structure of delphinids, and will provide details for developing appropriate breeding programs for bottlenose dolphins (Mats Amundin, Kolmårdens Djurpark, pers. commn., 1996, 2002). Behavioral data will be assessed to create the best possible enriched environment, considering all factors observed from both captive and wild habitats, to develop a successful breeding program for bottlenose dolphins. Programs to insure good health and survivability of captive dolphins will, comparatively, help in assessing the health and status of wild populations, and are especially critical for endangered species (like the vaquita) for which human encroachment and habitat degradation is threatening existence.
Ho1: The individual dolphin-association patterns within specific group types (e.g., mother/calf pairs, same sex and same age groups) are unique to each setting when observed in and compared between the captive and wild environments.
Ho2: Dolphin group type, i.e., group size and age/sex classification, is not a factor in the amount of time spent engaged in certain behaviors (e.g., pectoral fin rubs) or behavioral contexts (e.g., play).
Ho3: Specific action patterns, or behaviors, such as pectoral fin rubbing or bottom grubbing, are observed with similar frequency given particular activities regardless of whether the individual is captive or wild.
Ho4: Both captive and wild dolphins use pectoral fin rubs and touches for similar functions.
Ho5: Captive and wild dolphins produce whistles with similar variation and repertoire.
Ho6: In both the captive and wild settings, dolphin use of vocal and behavioral signals changes with age – i.e., ontogeny is a modifying factor (cue) to signal use and development.
1) To identify sex and age differences in the association patterns of the wild and captive dolphin study populations.
2) To characterize and quantify the amount of time spent by individual dolphins in specific group types.
3) To identify the number of dolphins involved in various behavioral contexts, including affiliative and aggressive social interactions, foraging, play.
4) To record specific action patterns of individual dolphins occurring within given behavioral contexts.
5) To record behaviors of dolphins of specific age and sex categories.
6) To examine and compare how dolphins use their pectoral fins/bodies to exchange touches and rubs.
7) To identify the amount of time spent engaged in different behavioral contexts or specific action patterns by each group type observed.
8) To document whistle production and use to individually identified dolphins given specific behavioral activities and group composition.
Over 35 species of cetacean have been maintained in artificial environments since the early 1860s (Defran & Pryor, 1980). While descriptions of specific behaviors were first provided by Townsend (1914), the majority of information collected on captive dolphins has focused on collection, transport, husbandry and medicine (Defran & Pryor, 1980). One would also expect to find a rich literature on species-typical or comparative behaviors of captive cetaceans; however, published accounts on this topic are limited in number. Behavioral studies on dolphins have been weighted largely towards free-ranging individuals and groups: usually, observations were confined to surface follows or documentation of general behavioral activities (e.g., Würsig & Würsig, 1979; Wells et al., 1987; Norris et al., 1994). Still, detailed documentation on the association patterns of male dolphins with other males and with females was the focus of two recent studies (for bottlenose dolphins Tursiops truncatus, Connor, 1990; for Hawaiian spinner dolphins Stenella longirostris, Östman, 1994). For both the Hawaiian spinner dolphins (Östman, 1994) and bottlenose dolphins in Shark Bay (Connor, 1990), male-male associations were stronger than most other bonds observed. Males form coalitions of two to three individuals and at times form multilevel associations between coalitions when competing for females (Connor, 1990). As longitudinal studies on dolphin social behavior enter their third and forth decades, life strategy patterns are becoming apparent. Future comparisons with terrestrial social animals will provide an evolutionary perspective on social behavior and communication.
Systematic observations of a captive, social group of dolphins would provide valuable information on specific behavioral events among associates as related to age/sex classes, group dynamics, or individual interactions. Conversely, no systematic or quantifiable information gathered from field studies of dolphin social behavior has been used for understanding the behavior and interactions of captive dolphins. Comparisons of data collected on a social group of captive dolphins with data collected on free-ranging delphinids would elucidate details of dolphin associations, behavioral interactions and social life. Observations of captives can yield lengthy, detailed records of interactions among individuals and within the group (Gales & Waples, 1993; Nelson & Lien, 1994; Renjun et al., 1994). Data from free-ranging groups provide information on the behaviors, social relationships, individual association types and groupings of dolphins in their natural setting.
Within the past two decades, several aquaria have begun to house several dolphins together in larger pools: a trend also apparent in zoo’s and wild animal parks (Inglis & Shepherd, 1990; Gorman, 1994). This restructuring is a dedicated effort to create breeding groups and expand the facility with more pool, giving more options to manipulate the social setting of the dolphins present. Well-adjusted, healthy, happy dolphins are important to a successful breeding program (Ralls, 1989; Ridgway et al., 1989; Markowitz, 1990). Providing an atmosphere that is behaviorally and socially stimulating, as well as physically large enough, will yield successful results in the breeding of captive dolphins (Ridgway et al., 1989; Markowitz, 1990). Comparable data sets between captive and free-ranging populations will provide invaluable information on suitable characteristics and parameters of the captive environment with regard to approximations of the free-ranging social system of dolphins.
The aquatic lifestyle of dolphins has resulted in the evolution of unique adaptations for communication and social interactions. As a result, signaling social cues may be mediated using physical, acoustic, or visual contact and, in turn, may be used singly or in combination, depending on the intended message Dudzinski (1998). Dudzinski (1998) reports posturing by dolphin’s functions to indicate the intent or meaning of the acoustic message in differing contexts: physical contact and vocal type vary significantly with behavioral activity, group type and age. Tactile and vocal signals were used concurrently, to emphasize or enhance a message, or they were used separately to indicate a specific signal.
Dolphins are tactile mammals: type, location and duration of touch by a dolphin’s pectoral fin can convey different meanings. Dolphins use pectoral fin rubs/touches to maintain social bonds, reprimand young, and in greeting (Dudzinski et al., 2009, Sakai 2002). It also seems that young dolphins must learn the appropriate use of pectoral fin touches. From almost 2,000 minutes of video we documented almost 1000 pectoral fin contacts in Bahamas’ Atlantic spotted dolphins and Mikura Island, Japan, bottlenose dolphins (Dudzinski et al., 2009). In both species, the rubber (“pec fin dolphin”) initiated touches more often than the rubbee (“body touched dolphin”). The rubber also terminated touches significantly more often than the rubbee. In both species, the back (forward of the dorsal fin), lateral peduncle, face, and pectoral fin were touched significantly more than any other body part. Pectoral touches were observed more from mix and adult female(s) with juveniles groups during social and play contexts for both species. For both species, the initiator (whether rubber or rubbee) was primarily female with age distribution relatively even for the rubber role, but skewed to younger spotted dolphin rubbees versus older bottlenose dolphin rubbees. It will be interesting to determine whether these trends hold for dolphins in the captive setting. RIMS dolphins offer a significant advantage to the study of wild dolphins: a longer observation time as well as the possibility to examine individual differences in pectoral fin exchanges as well as the role of learning among younger dolphins with respect to proper signal exchange and social development.
The signature whistle hypothesis was first introduced by David and Melba Caldwell in 1965. They observed that each dolphin in a captive environment tended to produce whistles that were individually distinct and stereotyped in certain acoustical features. Since this study, signature whistles have been documented in more than 300 individual dolphins in a variety of locations, both captive and wild (Sayigh, 2002). Recent studies have suggested that the signature whistle hypothesis is incomplete and the dolphin whistle repertoire still needs to be analyzed with respect to behavioral context and social relationships. Whether dolphins are actually using a wide range of whistles during their vocal exchanges or primarily producing signature whistles as more of a functional aspect remains to be seen (McCowan & Reiss, 1995). The extent of the dolphin’s whistle repertoire, including the actual function(s) of the signature whistle can be determined by studying the ontogeny of whistles in captive-born dolphins from similar and different social and acoustic environments (McCowan & Reiss, 1995). Infant dolphins also show a remarkable ability to modify the structure of a vocal signal as a result of experience with those of other individuals, ie, vocal learning (McCowan & Reiss, 1995). Vocal learning is an important factor in the ontogeny of an individually distinctive signature whistle during an infant’s development (Janik, 2000).
One possible function of the signature whistle is the concept of cohesion. During a coordinated or cooperative activity, communication is required between individuals. If an individual has a specific role to play during this activity, then a method of identifying each other is needed (Dudzinski et al., 2002). Dolphins are gregarious and often coordinate activities and must find each other in a variety of situations (Richardson et al., 1995). Another suggested function is that signature whistles are used to initiate reunions between individuals. Highly individualized signature whistles are used in a fission-fusion society in which individuals (specifically mother and infant) join and leave temporarily, while maintaining long-term associations with particular individuals. Thus, the whistle would convey context-specific information about the identity, location and navigation to reunite as well as querying the receiver for similar information (Janik et al., 1994).
Since its discovery, many factors (e.g., development and function) about the signature whistle hypothesis are still uncertain and incomplete. It is clear that further research needs to be done to better understand the complexity and role of the signature whistle within dolphin society. Developmental factors would include the influence of the auditory environment and the role of mimicry. The influence of the auditory environment can be seen by the differences of the whistle structure in captive and wild dolphins. Mimicry and imitation are features of vocal learning, however, it is unclear how confusion is avoided in group situations. The facilities at RIMS provide ample opportunity to study further the signature whistle.
Identifying and understanding the role that vocalizations and behaviors (e.g., posturing, gestures, touch) play in communicating the state or intent of an individual would provide additional insight into the social structure of coastal dolphins. The behavioral repertoire of animals housed in large natural enclosures, linked to the local ecosystem, may differ from those found in traditional captive study situations. Facilities such as the Roatan Institute of Marine Science, which utilize natural, flow-through sea water enclosures, are capable of maintaining larger social groups of dolphins than most aquaria and therefore present an ideal location for studying captive dolphin behavior and their social hierarchies.
METHODS FOR THIS STUDY
Three dolphin study groups will be observed: two wild resident groups and one captive population. Data on signal exchange and social interactions among Atlantic spotted dolphins (Stenella frontalis) in the Bahamas and among bottlenose dolphins (Tursiops aduncus) at Mikura Island, Japan, have been collected for twelve years (Dudzinski 1998, unpublished data). Histories, patterns of association and behavior are well-known (and continuing to be understood) from both of these groups (e.g., Dudzinski 1998; Herzing 1991, 1997; Kogi et al., 2004). These two dolphin groups represent the wild populations of this study. In addition, for the proposed research plan, we propose to observe and record behavior and sounds from the thriving bottlenose dolphin (Tursiops truncatus) group at the Roatan Institute of Marine Sciences (RIMS) Roatan, Honduras.
The RIMS dolphins are housed in two large natural enclosures, which link the animals to the local ecosystem. The facility currently houses 24 captive bottlenose dolphins (some wild caught and some captive-born dolphins). These dolphins are a mixture of males and females, ranging in age from several months to ~35 years. RIMS performed its first collection in 1989 with the authorization of permits from the Department of Natural Resources, Honduras. Dolphin encounters began shortly thereafter (1990), open water dives on the adjacent reef began with dolphins in 1991. Since 1989, RIMS has offered various programs to interact with the dolphins in their care. In 2014, those programs include dolphin encounters, dolphin swims, dolphin action swims and open water dolphin dives.
This study will provide extensive underwater observations on dolphin behaviors, association patterns, and social interactions in both wild and captive habitats, following a protocol of focal animal follows and an all-occurrence behavior sampling technique (Altmann, 1974; Martin & Bateson, 1986). A twelve-year database currently exists on two study populations of free-ranging dolphins: Bahamas’ Atlantic spotted dolphins and bottlenose dolphins around Mikura Island, Japan. These data will be used for comparison purposes since we will follow the same protocol as for previous data collection. Observations on both wild dolphin groups will continue on a seasonal basis. Real-time behavioral observations will be enhanced with video and sound recordings to study dynamics of inter-animal relations, associations, and the social structure of dolphins. Videography permits the documentation of subtle within-group signaling of dolphins underwater, where they spend the majority of their time. Observations on the captive bottlenose dolphins at RIMS will be conducted while swimming in the same pen as the dolphins and from surface platforms for above-water, simultaneous documentation of behavior and activity. Surface observations of the bottlenose dolphins at RIMS will follow both opportunistic and scan focal animal sampling protocols. Scan samples will be conducted when underwater observers are not in the water. Opportunistic focal sampling will be conducted when underwater observers are present with a focus on following individuals in close proximity to the underwater observer. General behaviors as well as those directed towards the observer will be documented in an attempt to control for the presence of the swimmer.
Focal individuals are chosen randomly from study dolphins within the different age/sex classes. A focal bout starts as soon as the observer is in position at the bottom of the enclosure and focal subject identified. The bout or video recording continues until the animal is out of view. Therefore, the duration of focal follows is dictated by the observer’s ability to visually track each dolphin within the sea enclosure. Anecdotal records of new scars, and teeth rake marks on specific dolphins will be kept as well as observations of unique behavioral events or interactions between dolphins or directed towards humans. These records will be used for descriptive analyses of dolphin social interactions, and corroborate assignment of contexts to encounters.
Individual dolphin sex, age and identification are made possible by the RIMS dolphin staff: the dolphins are handled many times daily as part of husbandry training. Also, dolphin identification cards including views of each dolphin’s face, left and ride sides, dorsal fin, pectoral fins and tail will be created for use by all observers. These cards will be used to train volunteer observers (students or ecotourists participating in dolphin research) for identifying and recognizing individual dolphins from video records.
Previous data on both wild dolphin groups have been gathered during swim-with-dolphin programs: passenger participation offset research expenses. Volunteer assistance has multiple benefits: expanded search effort in the field, complete observation of the study group and overlapping schedules to avoid observer fatigue. During on-sight observations of the RIMS dolphins, three weeks will include 10 – 12 volunteer participants. These volunteers are ecotourists interested in dolphin research and conservation. They will be taught proper observation technique and will work with one of two researchers to observe and record dolphin behavioral actions. Volunteers will not conduct underwater video observations but will conduct surface observations while a researcher is recording underwater. Volunteers will also assist with preliminary data analyses: documenting identified dolphins from each clip of video.
By having volunteers, we increase our research effort but also contribute an educational component directly to the participant. Informal lectures will be held each evening during the week-long research ecotour. It is our aim to provide to our volunteers a rich educational and entertaining experience related to science and research that will lead to continued participation in conservation of our natural resources and the oceans.
HOW WILL OUR PROPOSED RESEARCH HELP ENHANCE SCIENCE & EDUCATION PROGRAMS?
Science is a collaborative endeavor with an emphasis on information sharing. Results should not only be shared within the scientific community, but be disseminated to the public audience. People will only protect what they know and love. It is our responsibility to introduce the public audience to the wonders of our scientific and natural world.
The comparative research outlined in this proposal will be used as a foundation from which to increase public awareness of dolphin behavior, communication and conservation. Students and members of the general public will be encouraged to participate in various aspects of the science – from data collection to data analyses to presentation of results and findings. Opportunities will be provided to permit students of all ages to experience field work and science through interactive displays and “immersive”, interactive internet programs. This proposal benefits by international collaboration among universities, aquaria, new technology companies and communities. Through expansive education programs such as this, we teach people about dolphins and their behavior but more importantly about their environment. By catching the public attention with the animals, technology and science, we can better urge them to act to conserve the natural environment to help protect dolphins and the oceans.
Altmann J (1974) Observational study of behavior: sampling methods. Behaviour 49:227-267
Cheney DL, Seyfarth RM (1990) How monkeys see the world: inside the mind of another species. University of Chicago Press, Chicago
Connor RC (1990) Alliances among male bottlenose dolphins and comparative analyses of mutualism. Ph.D. Dissertation. The University of Michigan, Michigan, 139pp
Defran RH, Pryor K (1980) The behavior and training of cetaceans in captivity. In: Herman L, (ed) Cetacean Behavior: Mechanisms and Functions. John Wiley & sons, New York
Dudzinski KM (1998). Contact behavior and signal exchange in Atlantic spotted dolphins (Stenella frontalis). Aquatic Mammals 24: 1-14.
Dudzinski KM, Gregg JD, Ribic CA, Kuczaj SA (2009) A comparison of pectoral fin contact between two different wild dolphin populations. Behavioural Processes 80: 182-190.
Dudzinski KM, Thomas JA, Douaze E (2002) “Communication” in The Encyclopedia of Marine Mammals. edited by William F. Perrin, Bernd Wursig, & J. G. M. Thewissen. Academic Press. San Diego, pp. 248-267.
Herzing DL (1991) Family, friends and neighbors. Whalewatcher 26: 13-15.
Herzing DL (1997) The life history of free-ranging Atlantic spotted dolphins (Stenella frontalis): age classes, color phases, and female reproduction. Marine Mammal Science 13: 576-595
Gales N, Waples K (1993) The rehabilitation and release of bottlenose dolphins from Atlantis Marine Park, Western Australia. Aquatic Mammals 19: 49-59
Gorman P (1994) The doctor is out. Wildlife Conservation 97:58-67
Inglis IR, Shepherd DS (1990) Communication. In: Monaghan P, Woodbush D (eds) Managing the Behavior of Animals. Chapman and Hall, New York, pp 72-122
Janik VM (2000) Whistle matching in wild bottlenose dolphins (Tursiops truncatus). Science 289: 1355-1357.
Janik VM, Dehnhardt G, Todt D (1994) Signature whistle variations in a bottlenose dolphin, Tursiops truncatus. Behavioural Ecology & Sociobiology 35: 243-248
Kogi K, Hishii T, Imamura A, Eiji O, Dudzinski KM (2004) Population demographics, including composition, reproductive rates, population size estimates, and preliminary behavioral descriptions, for an eight-year period in a longitudinal study of Indo-Pacific bottlenose dolphins (Tursiops aduncus) around Mikura Island, Japan. Marine Mammal Science 20(3): 510-526
Markowitz H (1990) Environmental opportunities and health care for marine mammals. In: Dierauf LA (ed) CRC Handbook of Marine Mammal Medicine: Health, Disease, and Rehabilitation. CRC Press, Boston, pp 483-488
Martin P, Bateson P (1986) Measuring Behavior An Introductory Guide. Cambridge University Press, New York
McCowan B, Reiss D (1995) Quantitative comparisons of whistle repertoires from captive adult bottlenose dolphins. (Delphin Tursiops truncatus). A revelation of the signature whistle hypothesis. Ethology, 100, 194-209.
McCowan B, Reiss D (1995) Whistle contour development in captive-born infant bottlenose dolphins Tursiops truncatus: Roles of learning. Journal of Comparative Psychology 103: 242-260.
Nelson DL, Lien J (1994) Behavior patterns of two captive Atlantic white-sided dolphins, Lagenorhynchus acutus. Aquatic Mammals 20: 1-10
Norris KS, Würsig B, Wells RS, Würsig M (1994) The Hawaiian Spinner Dolphin. University of California Press, Berkeley, 408pp
Ralls K (1989) A semi-captive breeding program for the baiji, Lipotes vexillifer: Genetic and demographic considerations. In: Perrin WF, Brownell RL, Kaiya Z, Jiankang L (eds) Biology and Conservation of the River Dolphins. IUCN No. 3, pp 150-156
Renjun L, Gewalt W, Neurohr B, Winkler A (1994) Comparative studies on the behavior of Inia geoffrensis and Lipotes vexillifer in artificial environments. Aq Mamm 20:39-45
Richardson JW, et al. (1995) Marine Mammals and Noise. San Diego, Ca. Academic Press, Inc., 1995.
Ridgway SH, Norris KS, Cornell LH (1989) Some considerations for those wishing to propagate platanistoid dolphins. In: Perrin WF, Brownell RL, Kaiya Z, Jiankang L (eds) Biology and Conservation of the River Dolphins. IUCN No. 3, pp 159-167
Sayigh LS (2002) “Signature Whistles” in The Encyclopedia of Marine Mammals. edited by William F. Perrin, Bernd Wursig, & J. G. M. Thewissen. Academic Press. San Diego, pp. 1081-1083.
Townsend C (1914) The porpoise in captivity. Zoologica 1:289-299
Tyack P (1986) Whistle repertoires of two bottlenosed dolphins, Tursiops truncatus: mimicry of signature whistles? Behav Ecol Sociobiol 18:251-257
Wells RS, Scott MD, Irvine AB (1987) The social structure of free-ranging bottlenose dolphins. In: Genoways HH (ed) Current Mammalogy. Plenum Press, New York, pp 247-305
Würsig B, Würsig M (1979) Behavior and ecology of the bottlenose dolphin, Tursiops truncatus, in the South Atlantic. Fish Bull 77:399-412