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Herein, we report a case of pregnancy of a female bottlenose dolphin (Tursiops truncatus) that was subjected to artificial insemination (AI) in water based on its estrous behavior using simple instruments. AI was performed on this female dolphin once or twice daily for 4 days at the detection of estrous behavior, such as floating horizontally and showing reduced responsiveness, likely indicating the appropriate timing for AI. The female was placed in supine a position in the water to position the genital slit above the water surface. A Nélaton catheter (Fr. 10, 40 cm length), with its tip modified, was inserted approximately 20 cm into the vagina through the genital slit, and 1–2 ml of fresh semen was injected. The AI procedure was performed within 1 min by two technicians. Thus, this AI method may be a new choice for artificial reproduction, as pregnancy success can be achieved with relatively less cost, less difficulty, and less invasive treatments of cetaceans.

Dolphins are known to recognize their environment through echolocation. Previous studies have reported that they can discriminate the shape, size, thickness, and even material of objects through echolocation. However, little is known about the discrimination of quantities other than size and thickness (e.g., the number of objects). It is also unclear whether Weber's law (i.e., ratio dependency) holds for quantity discrimination through echolocation. In this study, we examined relative quantity judgments of visually occluded objects presented underwater by bottlenose dolphins. We found that they could discriminate pairs of same-sized objects ranging from one to eight, with performance improving as the difference ratio between the two numbers increased. In addition, their performance also improved as the magnitude of the number of objects involved increased. An additional test revealed that the accuracy of discrimination through echolocation was comparable to that of visual relative quantity judgments of the objects presented above water. On the other hand, under the condition that the overall size of each object (i.e., the sum of areas) was incongruent with the number of objects, performance was lower than when number and size were covarying. However, even within the incongruent condition, the effect of the number ratio was still observed, suggesting that the dolphins might have used various types of quantity information, such as number and size, flexibly to solve the task. [ABSTRACT FROM AUTHOR]

A 15-y-old captive-born female bottlenose dolphin (Tursiops truncatus) had slowly progressive lethargy, inappetence, and pallor of the oral mucosa. Serial hemograms and serum biochemistry analysis revealed hemolyzed plasma, gradually severe anemia with reticulocytosis, spherocytosis, pronounced neutrophilia with left shift and toxic change, and indirect hyperbilirubinemia. Urinalysis identified both hemoglobinuria and bilirubinuria. Hyperglobulinemia with polyclonal gammopathy was evident by protein electrophoresis, and the saline agglutination test was positive. Splenomegaly and hyperechogenic liver were also observed on ultrasound. These findings meet the diagnostic criteria established for immune-mediated hemolytic anemia (IMHA) in small animals, which is extremely rare in cetacean species, and, to our knowledge, has not been fully documented. Several potential triggers of a secondary IMHA were ruled out, including the most common cetacean virus, exposure to new drugs, and recent vaccination events. Following recommendations from companion animal medicine, immunosuppressive therapy was implemented and proved effective in this bottlenose dolphin; the CBC returned to normal after 3 mo of treatment. [ABSTRACT FROM AUTHOR]

Because climate change and the biodiversity crisis are driven by human actions, determining psychological mechanisms underpinning support for environmental action is an urgent priority. Here, we experimentally tested for mechanisms promoting conservation-related motivation and behavior toward a flagship species, wild Tamanend's bottlenose dolphins. Following evidence that empathy increases prosocial motivations and behavior, and that the ability to identify individual humans promotes empathy, we tested whether this relationship applied to the ability to identify individual dolphins. Participants identified dolphins from their dorsal fins at above chance levels, and better individuation correlated with higher empathy for dolphins and higher willingness to pledge environmental behaviors. Pairing a narrative with an image of an injured dolphin leads to higher donations relative to a narrative alone. Our novel finding that the ability to individually identify dolphins relates to empathy and conservation-related behavior suggests pathways for strengthening environmental attitudes and behavior. [ABSTRACT FROM AUTHOR]

"Gaze following"-when one individual witnesses another shift its orientation, and then re-orients in the same direction-has been observed in a wide range of species. Related work with dolphins has to date focused on human-dolphin interactions. In this conspecific study, we examined a group of dolphins orienting, in passing, to gateways between their pools, as opportunities for witnesses to demonstrate "gaze following". Seven bottlenose dolphins were synchronously videotaped on six underwater cameras, for 21 h over three days, and the recordings analyzed by trained observers. The identities of all animals present, their partner state, and whether and to what degree they had altered their access to the gate (e.g., from Monocular to Binocular, or Binocular to Visio-Echoic) was recorded. Compared to animals that did not witness such a change, witnesses of an increase in access by another dolphin were significantly more likely to also act to increase their own access. We observed 460 such cases of "gaze following" in these animals. Dolphins who were partnered (showed sustained swimming within 1 body length) were significantly more likely, than non-partnered animals, to "gaze follow". Dolphins also showed a significant tendency toward matching the kind of access they observed. No significant difference was found in the presence of animals in the back pools, during changes in orientation that were followed, versus in those that were not. These findings support adding bottlenose dolphins to the growing list of species that display conspecific "gaze following".

Social tolerance is an essential feature of social life that can determine the good functioning of a group of animals. Play behaviors, like social play and playing with objects, are frequently associated with positive emotional and welfare states. As a result, zoos use various strategies to promote both social tolerance and play with objects. Providing animals with cognitive environmental enrichment can be an effective tool to achieve these goals. Here we tested whether cognitive environmental enrichment can promote social tolerance and play with objects in bottlenose dolphins (Tursiops truncatus). To this end, we provided a group of five dolphins with two types of cognitive enrichment: one for individual use and one for cooperative use, both based on the rope-pulling task paradigm. Then we evaluated whether social tolerance and play with objects had increased after we provided dolphins with the two enrichments. Our results go in this direction, showing that after we provided dolphins with the enrichments, their intolerance behaviors decreased, both during feeding sessions and play sessions, while their play with objects increased. As a result, the two enrichments we used could be useful for improving dolphins' housing conditions. [ABSTRACT FROM AUTHOR]

Environmental enrichment is an essential component of the management policies used by zoos and aquaria to promote animals' welfare. However, when enrichments are provided several times, they can cause habituation and lose their enrichment effects. A simple method to avoid it could be making a preventive assessment about the trend of animals' interest in a stimulus provided several times. Here, we hypothesized that anticipatory behavior could be used to assess the decrease in interest in playing with objects when the activity is repeated. Moreover, we also assumed that this could be done before providing objects to play with. Our results support this hypothesis. Specifically, we found a positive correlation between the time the 7 dolphins tested spent performing anticipatory behavior before the enrichment sessions and the time they spent playing with objects during those sessions. As a result, anticipatory behavior performed before enrichment sessions predicted dolphins' interest in the session and allowed us to assess whether the sessions had lost their enrichment effect. [ABSTRACT FROM AUTHOR]

Cetaceans can serve as sentinel species in marine environments as long-lived, apex predators that can concentrate environmental contaminants with potential health consequences. Thus, monitoring the well-being of these species may provide an additional indicator of ecosystem health. In cetaceans, one method for assessing individual and population health is by examining skin conditions. For decades, skin lesions have been increasingly documented in coastal populations of bottlenose dolphins (Tursiops spp.) worldwide. Lesion presence can indicate diminished health and may reflect environmental stressors. Herein, we document the prevalence of epidermal lesions/marks in bottlenose dolphins from the waters off New York and New Jersey during their seasonal presence from spring to fall. Photographs of distinct individuals sighted from May to October 2017 to 2021 were compiled into a catalog, and skin lesions were categorized and counted. Annually, the lowest skin lesion prevalence was in 2021 (p = 0.31), and the highest was in 2017 (p = 0.81). By month, prevalence generally decreased from spring to fall. Overall lesion prevalence in this population was higher than reported estimates for other populations in the coastal waters of the United States. The five most common categories were cloudy white spots, dark spots, white amorphous lesions, tattoo lesions, and dark fringe lesions; and the three most common groups were potentially pathogenic lesions, hypopigmentation, and rake mark-associated potentially pathogenic lesions. Some of the observed lesions have been associated with viral infections that may be exacerbated by environmental stressors. This research establishes an important baseline for further studies into bottlenose dolphin population health in and around the New York--New Jersey Harbor Estuary, particularly given the continued expansion of anthropogenic activities, including those related to forthcoming offshore wind development. [ABSTRACT FROM AUTHOR]

UNLABELLED: Social structuring from assortative associations may affect individual fitness, as well as population-level processes. Gaining a broader understanding of social structure can improve our knowledge of social evolution and inform wildlife conservation. We investigated association patterns and community structure of female Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia, assessing the role of kinship, shared culturally transmitted foraging techniques, and habitat similarity based on water depth. Our results indicated that associations are influenced by a combination of uni- and biparental relatedness, cultural behaviour and habitat similarity, as these were positively correlated with a measure of dyadic association. These findings were matched in a community level analysis. Members of the same communities overwhelmingly shared the same habitat and foraging techniques, demonstrating a strong homophilic tendency. Both uni- and biparental relatedness between dyads were higher within than between communities. Our results illustrate that intraspecific variation in sociality in bottlenose dolphins is influenced by a complex combination of genetic, cultural, and environmental aspects. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42991-022-00259-x.

Emotions in animals may be expressed by arousal and understanding this often relies upon the monitoring of their behaviour. Under human care, animals’ arousal states may be linked to husbandry decisions, whereby animals may display arousal responses to scheduled events such as feeding and human interaction. Here, we investigate vocal correlates of arousal associated with public presentations of bottlenose dolphins (Tursiops spp.) in human care by comparing vocal production rates and characteristics between high and low arousal contexts. Elevated arousal during the day compared with overnight was characterised by increased signature and non-signature whistle production. High intensity broadband crack vocalisations were produced less than whistles during the day and did not correlate with increased arousal around presentation times. Three of ten dolphins increased signature whistle production before and/or after presentation sessions, indicating elevated arousal and variation in individual responses. Many individuals elevated minimum frequency and suppressed maximum frequency of signature whistles in a way that correlated with higher arousal contexts, indicating that these may therefore be good indicators of changes in arousal state. Overall, our study demonstrates that passive acoustic monitoring can provide a useful indication of arousal linked to husbandry decisions, and that individual variation in vocal responses, likely linked to personality, is important to consider.

Anticipatory behavior describes the actions taken to prepare for an upcoming event. It is considered a promising tool for welfare assessment, but it is not fully applied in zoos and other facilities. This is probably due to the need to train animals, which can take a long time and make its use impractical. In this work, we tested, on a group of six dolphins (Tursiops truncatus), the effectiveness of a new technique to induce and measure anticipatory behavior without training animals. Our results show how this new methodology, which we called The Fast Technique (TFT), has been able to induce and measure anticipatory behavior toward the event studied, i.e., the play sessions with objects (PSO). Furthermore, it has produced the same result obtained with The Classical Technique (TCT), which requires a training phase. Therefore, our finding demonstrates the efficacy of a new technique that could facilitate the use of anticipatory behavior for both research and animal welfare assessment protocols. [ABSTRACT FROM AUTHOR]

The relationship between a dolphin mother and her calf has been well studied, but details regarding tactile exchanges within these dyads are limited. Contacts between five adult female bottlenose dolphins (Tursiops truncatus) and their calves, with data from three pairs analyzed statistically, were examined from video collected in October 2017, 2018, 2019, and in January 2018. Of 289 contact events, calves initiated 65.7% (n = 190), of which 82.6% (n = 157) were affiliative; 77.8% (n = 77) of mother-initiated contacts were categorized similarly. Thus, the overall trend for mother-calf contacts was affiliative. Mothers initiated contact with the dorsal fin less often (n = 3), while calves initiated with their dorsal fin more often (n = 40), especially one-year-old (C1) calves (n = 33). The body was used to initiate contact more by three-year-old (C3) calves (n = 47) and less by C1 calves (n = 22). Both results are likely an artifact of the infant position used by calves at different developmental stages. Only two-year-old (C2) calves initiated agonistic contact with their rostrum (n = 4); 75% of these contacts were initiated by one male calf. Mothers used the body to initiate contact with most calf ages, though contact by pectoral fin occurred more often than expected with their C2 calves (n = 11). Since 72.7% of these contacts came from one mother, a specific maternal style may be present. Only one mother used her rostrum with her C3 calf to initiate agonistic contacts; all others used the fluke. Several variables, including individual preference, calf sex, and maternal experience, may explain some of the contact patterns, but a larger sample size is needed to illustrate potential patterns among pairs. Still, these results support the notion that mother-calf dyads share more affiliative than agonistic contacts, expanding our knowledge on the tactile relationships of mother-calf pairs. [ABSTRACT FROM AUTHOR]

Emotions in animals may be expressed by arousal and understanding this often relies upon the monitoring of their behaviour. Under human care, animals' arousal states may be linked to husbandry decisions, whereby animals may display arousal responses to scheduled events such as feeding and human interaction. Here, we investigate vocal correlates of arousal associated with public presentations of bottlenose dolphins (Tursiops spp.) in human care by comparing vocal production rates and characteristics between high and low arousal contexts. Elevated arousal during the day compared with overnight was characterised by increased signature and non-signature whistle production. High intensity broadband crack vocalisations were produced less than whistles during the day and did not correlate with increased arousal around presentation times. Three of ten dolphins increased signature whistle production before and/or after presentation sessions, indicating elevated arousal and variation in individual responses. Many individuals elevated minimum frequency and suppressed maximum frequency of signature whistles in a way that correlated with higher arousal contexts, indicating that these may therefore be good indicators of changes in arousal state. Overall, our study demonstrates that passive acoustic monitoring can provide a useful indication of arousal linked to husbandry decisions, and that individual variation in vocal responses, likely linked to personality, is important to consider. [ABSTRACT FROM AUTHOR]

Passive acoustic monitoring (PAM) is one of the most effective and widely used methods for marine mammal detection and population density estimation. In most cases, it is associated with an inevitably large volume of raw acoustic data, making analysis exclusively by human experts challenging and extremely time-demanding. We present a neural network algorithm for detection of tonal signals produced by toothed cetaceans which allocates time intervals with high likelihood of marine mammal signal presence in underwater sound recordings. The proposed model is based on a convolutional neural network (CNN) of the ResNet152 architecture used as a backbone with additional linear layers. The input data for the model are spectrograms of short segments of underwater sound recordings. Training of the network was performed on a benchmark dataset of bottlenose dolphin whistles labeled by human experts. Analysis of the performance metrics (Precision, Recall, and F1-score) showed the proposed model's superiority in comparison to widely used acoustic energy-based approaches. In virtue of the model's versatility, we believe that it can be successfully used for detection of tonal signals of other species characterized by producing tonal acoustic signals. This assumption was confirmed by preliminary results of the application of the developed CNN to a large archive of the White Sea beluga whale recordings. [ABSTRACT FROM AUTHOR]

We diagnosed fatal Erysipelothrix rhusiopathiae sepsis in 3 stranded bottlenose dolphins (Tursiops truncatus) during summer 2022, in San Diego, California, USA. The previously undetected disease in this relatively small, regional population of dolphins most likely indicates an environmental or biological change in the coastal ocean or organisms.

The Charleston Harbor in South Carolina (SC) is a major port that experiences high levels of vessel traffic. Historical analyses of coastal bottlenose dolphin (Tursiops truncatus, now Tursiops erebennus) sightings identified multiple core use areas in the harbor that overlap with these anthropogenic activities. Informed by these long-term spatial data, passive acoustic monitoring, visual surveys, and prey sampling were conducted from December 2017 to June 2019 to assess the relationships and multivariate interactions that may influence dolphin vocalization patterns. Vocalizations varied spatially and temporally, peaking in fall and winter months coinciding with decreases in water temperature and daylight hours, following patterns previously reported in other SC estuaries. Dolphin prey and total fish abundance decreased with water temperature, which may indicate that dolphins echolocate and whistle more frequently in the winter months when prey are scarce and soundproducing species are less soniferous. Dolphin sightings and vocalizations were highly correlated. Dolphin occurrence was highest in the areas surrounding the confluence of the Cooper and Wando Rivers, along the shipping channel, where vessel and sound-producing fish detections were greatest. When vessel noise occurred, dolphins increased their vocalizations, which suggests that this population may be modifying its acoustic repertoire in response to increased noise levels. Multivariate interactions indicate strong spatial and seasonal patterns in vocalization rates that may be associated with dolphin and prey abundance as well as noise-induced redundancy. [ABSTRACT FROM AUTHOR]

Interactions between bottlenose dolphin and recreational rod and reel fisheries are a complex issue for resource managers in the United States, which may impact anglers' catch and lead to dangerous situations for scavenging or depredating dolphins. To examine this issue, we analyzed data collected by observers on for-hire fishing vessels off the eastern U.S. Gulf Coast from 2009 to 2020. A generalized additive model indicated number of anglers, number of discarded fish, proximity to shore, prior scavenging events, type of released fish, and area fished were all significant predictors of scavenging by dolphins. The Florida panhandle had the highest odds of scavenging, while scavenging in the Big Bend and Tampa Bay has increased through time. The Florida panhandle is a wellknown area for illegal feeding of dolphins, suggesting human behavior may be influencing fisheries interactions. Model outputs indicate that dolphins are primarily cuing on fishing activity rather than number of discards, but are more likely to scavenge discards from the family Lutjanidae (snappers), which comprised 40% of observed discards but 80% of scavenging events. This study highlights factors influencing the frequency of dolphin scavenging events, guiding managers and scientists on additional studies and mitigation measures needed to address this issue. [ABSTRACT FROM AUTHOR]

Recreational use of wild spaces is increasingly popular, resulting in a burgeoning tourism industry. Such activities can degrade the environment and disrupt the behaviour and natural function of organisms. A small population of bottlenose dolphins (Tursiops truncatus) is resident in Dusky Sound, New Zealand, a fjord with increasing human use. Dolphins, as top predators, play an important role within ecosystems and are at risk of long-term negative consequences from behavioural changes when exposed to high levels of vessel activity. A better understanding of the distribution of the dolphins in Dusky Sound would provide a framework for developing management within the fjord. Here we describe where dolphins were most frequently found, based on >40,000 km of photo-ID survey effort conducted over 10 years. Kernel density estimation revealed two large core areas that remained consistent over the duration of this study. This information could be used to determine areas within Dusky Sound where human activities around dolphins could be managed to avoid anthropogenically driven detrimental impacts. We suggest the following: (1) establish dolphin protection zones, (2) create a marine mammal sanctuary, (3) extend marine reserve boundaries, and/or (4) lower catch limits for fish within the fjord boundaries. [ABSTRACT FROM AUTHOR]

The social intelligence hypothesis holds that complex social relationships are the major selective force underlying the evolution of large brain size and intelligence. Complex social relationships are exemplified by coalitions and alliances that are mediated by affiliative behavior, resulting in differentiated but shifting relationships. Male Indo-Pacific bottlenose dolphins in Shark Bay, Australia, form three alliance levels or 'orders', primarily among non-relatives. Strategic alliance formation has been documented within both first- and second-order alliances and between second-order alliances ('third-order alliances'), revealing that the formation of strategic inter-group alliances is not limited to humans. Here we conducted a fine-scale study on 22 adult males over a 6-year period to determine if third-order alliance relationships are differentiated, and mediated by affiliative interactions. We found third-order alliance relationships were strongly differentiated, with key individuals playing a disproportionate role in maintaining alliances. Nonetheless, affiliative interactions occurred broadly between third-order allies, indicating males maintain bonds with third-order allies of varying strength. We also documented a shift in relationships and formation of a new third-order alliance. These findings further our understanding of dolphin alliance dynamics and provide evidence that strategic alliance formation is found in all three alliance levels, a phenomenon with no peer among non-human animals. [ABSTRACT FROM AUTHOR]

How do bottlenose dolphins visually perceive the space around them? In particular, what cues do they use as a frame of reference for left–right perception? To address this question, we examined the dolphin's responses to various manipulations of the spatial relationship between the dolphin and the trainer by using gestural signs for actions given by the trainer, which have different meanings in the left and right hands. When the dolphins were tested with their backs to the trainer (Experiment 1) or in an inverted position underwater (Experiments 2 and 3), correct responses from the trainer's perspective were maintained for signs related to movement direction instructions. In contrast, reversed responses were frequently observed for signs that required different sounds for the left and right hands. When the movement direction instructions were presented with symmetrical graphic signs such as " × " and "●", accuracy decreased in the inverted posture (Experiment 3). Furthermore, when the signs for sounds were presented from either the left or right side of the dolphin's body, performance was better when the side of the sign movement coincided with the body side on which it was presented than when it was mismatched (Experiment 4). In the final experiment, when one eye was covered with an eyecup, the results showed that, as in the case of body-side presentation, performance was better when the open eye coincided with the side on which the sign movement was presented. These results indicate that dolphins used the egocentric frame for visuospatial cognition. In addition, they showed better performances when the gestural signs were presented to the right eye, suggesting the possibility of a left-hemispheric advantage in the dolphin's visuospatial cognition. [ABSTRACT FROM AUTHOR]

Aim: Understanding the distribution of marine organisms is essential for effective management of highly mobile marine predators that face a variety of anthropogenic threats. Recent work has largely focused on modelling the distribution and abundance of marine mammals in relation to a suite of environmental variables. However, biotic interactions can largely drive distributions of these predators. We aim to identify how biotic and abiotic variables influence the distribution and abundance of a particular marine predator, the bottlenose dolphin (Tursiops truncatus), using multiple modelling approaches and conducting an extensive literature review. Location: Western North Atlantic continental shelf. Methods: We combined widespread marine mammal and fish and invertebrate surveys in an ensemble modelling approach to assess the relative importance and capacity of the environment and other marine species to predict the distribution of both coastal and offshore bottlenose dolphin ecotypes. We corroborate the modelled results with a systematic literature review on the prey of dolphins throughout the region to help explain patterns driven by prey availability, as well as reveal new ones that may not necessarily be a predator–prey relationship. Results: We find that coastal bottlenose dolphin distributions are associated with one family of fishes, the Sciaenidae, or drum family, and predictions slightly improve when using only fish versus only environmental variables. The literature review suggests that this tight coupling is likely a predator–prey relationship. Comparatively, offshore dolphin distributions are more strongly related to environmental variables, and predictions are better for environmental‐only models. As revealed by the literature review, this may be due to a mismatch between the animals caught in the fish and invertebrate surveys and the predominant prey of offshore dolphins, notably squid. Main Conclusions: Incorporating prey species into distribution models, especially for coastal bottlenose dolphins, can help inform ecological relationships and predict marine predator distributions. [ABSTRACT FROM AUTHOR]

Barnacles can reveal much about the physiology, health, and spatial ecology of their cetacean hosts. Here, we examine how temperature and hydrodynamic factors impact presence of Xenobalanus globicipitis, a pseudo‐stalked barnacle that attaches exclusively to cetaceans. We hypothesized that temperature is a key environmental factor (i.e., water temperature) and physiological factor, in that X. globicipitis prefers the warmest skin temperature for attachment, possibly as a mechanism for survival in colder waters. First, we demonstrate a global relationship between spatial ecology of host species and presence of X. globicipitis. Notably, X. globicipitis is absent in the four species occupying waters with the lowest sea surface temperature (SST) year‐round, but present in migratory species that likely acquire the barnacle in waters with higher SST. Second, barnacle attachment location on common bottlenose dolphin (Tursiops truncatus) dorsal fins corresponds with fin temperature and hydrodynamics. Although body temperature may influence attachment location on the body of the animal, hydrodynamic forces, as previously proposed, determine how well barnacles can remain attached during the adult stage. X. globicipitis prevalence likely provides important bioindicator, ecological, and physiological information about its host. As parasitic infestation has some cost, these results have implications for cetacean health in warming seas. [ABSTRACT FROM AUTHOR]

Bottlenose dolphins (Tursiops truncatus) are viewed as a highly intelligent species, capable of complex behaviors, requiring marine parks to maintain dynamic environmental enrichment procedures in order to ensure their optimal psychological and physiological well-being in human care. In this study, two experiments were conducted to determine the effects of different forms of enrichment on the behavior of bottlenose dolphins. In Experiment 1, the most successful enrichment included highly novel items, which resulted in avoidance, but also what is frequently considered positive behavioral changes including a reduction in circle swimming and an increase in social behavior. In Experiment 2, the use of choice resulted in negative unintended social consequences. These two experiments together demonstrate that the results of deploying enrichment may not be as clear-cut as previously presumed. In order to maintain positive benefits of enrichment, the results of this study suggest that unique forms of enrichment should be implemented on a variable schedule that is offered several times a year and consistently evaluated for effectiveness.

Laterality of eye use has been increasingly studied in cetaceans. Research supports that many cetacean species keep prey on the right side while feeding and preferentially view unfamiliar objects with the right eye. In contrast, the left eye has been used more by calves while in close proximity to their mothers. Despite some discrepancies across and within species, laterality of eye use generally indicates functional specialization of brain hemispheres in cetaceans. The present study aimed to examine laterality of eye use in bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis) under managed care. Subjects were video-recorded through an underwater window while viewing two different stimuli, one predictable and static and the other unpredictable and moving. Bottlenose dolphins displayed an overall right-eye preference, especially while viewing the unpredictable, moving stimulus. Rough-toothed dolphins did not display eye preference while viewing stimuli. No significant correlations between degree of laterality and behavioral interest in the stimuli were found. Only for bottlenose dolphins were the degree of laterality and curiosity ratings correlated. This study extends research on cetacean lateralization to a species not extensively examined and to stimuli that varied in movement and degree of predictability. Further research is needed to make conclusions regarding lateralization in cetaceans.

Homophilous behaviour plays a central role in the formation of human friendships. Individuals form social ties with others that show similar phenotypic traits, independently of relatedness. Evidence of such homophily can be found in bottlenose dolphins ( Tursiops aduncus) in Shark Bay, Western Australia, where females that use marine sponges as foraging tools often associate with other females that use sponges. 'Sponging' is a socially learned, time-consuming behaviour, transmitted from mother to calf. Previous research illustrated a strong female bias in adopting this technique. The lower propensity for males to engage in sponging may be due to its incompatibility with adult male-specific behaviours, particularly the formation of multi-level alliances. However, the link between sponging and male behaviour has never been formally tested. Here, we show that male spongers associated significantly more often with other male spongers irrespective of their level of relatedness. Male spongers spent significantly more time foraging, and less time resting and travelling, than did male non-spongers. Interestingly, we found no difference in time spent socializing. Our study provides novel insights into the relationship between tool use and activity budgets of male dolphins, and indicates social homophily in the second-order alliance composition of tool-using bottlenose dolphins.

Area-restricted search (ARS) behaviour is commonly used to characterize spatio-temporal variation in foraging activity of predators, but evidence of the drivers underlying this behaviour in marine systems is sparse. Advances in underwater sound recording techniques and automated processing of acoustic data now provide opportunities to investigate these questions where species use different vocalizations when encountering prey. Here, we used passive acoustics to investigate drivers of ARS behaviour in a population of dolphins and determined if residency in key foraging areas increased following encounters with prey. Analyses were based on two independent proxies of foraging: echolocation buzzes (widely used as foraging proxies) and bray calls (vocalizations linked to salmon predation attempts). Echolocation buzzes were extracted from echolocation data loggers and bray calls from broadband recordings by a convolutional neural network. We found a strong positive relationship between the duration of encounters and the frequency of both foraging proxies, supporting the theory that bottlenose dolphins engage in ARS behaviour in response to higher prey encounter rates. This study provides empirical evidence for one driver of ARS behaviour and demonstrates the potential for applying passive acoustic monitoring in combination with deep learning-based techniques to investigate the behaviour of vocal animals.

The preference tests have made a great contribution to promoting animal welfare. However, they are not always easily applicable and have some criticalities. Recently the anticipatory behavior has been used to detect the animals' preference. In this study, we attempted to investigate the relationship between preference and anticipatory behavior. To this end, we tested on a group of dolphins (Tursiops truncatus) whether, with anticipatory behavior, it is possible to distinguish the animals' preference for different objects and then use it as a preference test. Anticipatory behavior is exhibited throughout the animal kingdom, it is easy to induce and measure, and does not have the criticalities of other preference tests. Therefore, its use as preference test could facilitate the study of animals' preferences and contribute to the promotion of their welfare. Our results support the hypothesis of use anticipatory behavior as a preference test. In fact, dolphins have anticipated the arrival of objects highly preferred with a frequency three times higher than shown toward objects less preferred, providing further evidence of the correlation between anticipatory behavior and the animals' preference. [ABSTRACT FROM AUTHOR]

Over the last decades, large‐scale ecological projects have emerged that require collecting ecological data over broad spatial and temporal coverage. Yet, obtaining relevant information about large‐scale population dynamics from a single monitoring programme is challenging, and often several sources of data, possibly heterogeneous, need to be integrated. In this context, integrated models combine multiple data types into a single analysis to quantify the population dynamics of a targeted population. When working at large geographical scales, integrated spatial models have the potential to produce spatialized ecological estimates that would be difficult to obtain if data were analysed separately. In this study, we illustrate how spatial integrated modelling offers a relevant framework for conducting ecological inference at large scales. Focusing on the Mediterranean bottlenose dolphins (Tursiops truncatus), we combined 21,464 km of photo‐identification boat surveys collecting spatial capture–recapture data with 24,624 km of aerial line transect following a distance sampling protocol. We analysed spatial capture–recapture data together with distance sampling data to estimate the abundance and density of bottlenose dolphins. We compared the performances of the distance sampling model and the spatial capture–recapture model fitted independently to our integrated spatial model. The outputs of our spatial integrated models inform bottlenose dolphin ecological status in the French Mediterranean Sea and provide ecological indicators that are required for regional‐scale ecological assessments like the EU Marine Strategy Framework Directive. We argue that integrated spatial models are widely applicable and relevant to conservation research and biodiversity assessment at large spatial scales. [ABSTRACT FROM AUTHOR]

Passive acoustics are widely used to monitor the presence of dolphins in the marine environment. This study aims to introduce a low-cost and homemade approach for assembling a complete underwater microphone (i.e., the hydrophone), employing cheap and easy to obtain components. The hydrophone was assembled with two piezo disks connected in a balanced configuration and encased in a plastic container filled with plastic foam. The hydrophone's performance was validated by direct comparison with the commercially available AS-1 hydrophone (Aquarian Hydrophones, Anacortes, U.S.) on different underwater acoustic signals: artificial acoustic signals (ramp and multitone signals) and various dolphin vocalizations (whistle, echolocation clicks, and burst pulse signals). The sensitivity of the device's performance to changes in the emission source position was also tested. The results of the validation procedure on both artificial signals and real dolphin vocalizations showed that the significant cost savings associated with cheap technology had a minimal effect on the recording device's performance within the frequency range of 0–35 kHz. At this stage of experimentation, the global cost of the hydrophone could be estimated at a few euros, making it extremely price competitive when compared to more expensive commercially available models. In the future, this effective and low-cost technology would allow for continuous monitoring of the presence of free-ranging dolphins, significantly lowering the total cost of autonomous monitoring systems. This would permit broadening the monitored areas and creating a network of recorders, thus improving the acquisition of data. [ABSTRACT FROM AUTHOR]

The investigation of individual responses to unexpected stimuli or outcomes provides insights into basic cognitive processes, such as mental representations, emotional states of surprise, and detections of anomalies. Three experiments using a violation of expectation paradigm were conducted with 12 belugas and 17 bottlenose dolphins in managed care to test two classes of stimuli (humans and objects) in manipulated sequences of familiar and unfamiliar humans (Study 1, trainers and strangers), familiar and unfamiliar objects (Study 2, typical enrichment devices and new objects), and finally objects and humans (Study 3). Gaze durations were assessed for each condition in a given study during free-swim contexts. The results supported previous findings that visual stimuli, regardless of class, were stimulating and intriguing for both belugas and bottlenose dolphins. Belugas were more likely to gaze longer at human and object stimuli and tended to gaze longer at unexpected experiences than control or expected experiences. Bottlenose dolphins showed similar trends except when objects were involved. Individual variability was present for both species with some individuals showing stronger patterns of responses for expected experiences than others. After 2 years of intermittent experiments, belugas and bottlenose dolphins in managed care maintained their curiosity about visual stimuli, for which they received no primary reinforcement. Investigating responses to unexpected stimuli with animals in managed care may provide insight into how these animals respond to biologically relevant conditions, such as boat presence, predators, and unfamiliar conspecifics. [ABSTRACT FROM AUTHOR]

Creativity is considered one aspect of intelligence. Including creativity allows for more room for expression (e.g., participants can respond with movement instead of written or verbal responses) than in standard intelligence assessments. The Torrance Tests of Creative Thinking (TTCT; Torrance, 1974) are the leading method of assessing creative abilities in school-aged humans and above. To assess creativity in young humans and nonhuman animals, modifications must be made to facilitate nonverbal responses. In the current study, a cross-species comparison was conducted between preschoolers and bottlenose dolphins to examine responses to a modified creativity task in which both species were trained to demonstrate non-repeated behaviors to an “innovate” prompt. The resulting behaviors for the first test session were coded for fluency (number of non-repeated behaviors demonstrated), originality, and flexibility (low, moderate, or high activity level). Children and dolphins produced a similar number of non-repeated behaviors during individual test trials and also had similar originality scores. Related to flexibility, dolphins displayed more low energy activity levels compared to the children. Given the limited understanding of creative abilities in animals and young children, this comparison using a modified version of the TTCT offers exciting possibilities. These results could provide further evidence of similarities in cognitive processes for humans and nonhuman animals.

Nowadays, zoos and aquariums, along with the constant advancement of sociocultural moral values, are proactively committed to ensuring and safeguarding cetacean health standards. This entails developing new approaches to health assessments by embracing minimally invasive sampling methods and enhanced animal handling and management, among other aspects. Hence, in the present survey, to appraise skin diseases, the implementation of cytology cell samplers as a non-invasive skin sampling device on 18 bottlenose dolphins housed in two facilities in the Canary Islands during the months of April, October, and December 2019 was performed to isolate cetacean poxvirus in tattoo-like lesions through a real-time PCR-based method using the DNA polymerase gene. Samples were repeatedly collected over time from eleven tattoo-like lesions and from apparently healthy skin to serve as a control for all study animals. From a total of 55 skin samples, detection of the poxvirus was attained in 31 (56.36%); specifically, on 20 of 21 samples collected from tattoo-like lesions (95.23%) and on 11 of 34 samples acquired from apparently healthy skin (32.35%). Correspondingly, the current study constitutes the first report of the isolation of cetacean poxvirus in skin samples without macroscopical signs of tattoo lesions in cetaceans. Likewise, ten of the eleven dolphins that showed tattoo lesions housed in Facility 1 were positive for tattoo skin disease, while four dolphins held in Facility 2 were positive for cetacean poxvirus without ever showing clinical evidence of the disease. This raises the question of whether this pathogen can produce latent infections and whether progression of the disease may depend on environmental stimuli, viral load, or the good health/immunological status of individual animals. Accordingly, further scientific research on cetaceans under human care could provide the knowledge, skills, and resources to understand the host–pathogen dynamics of cetacean poxviruses and their effect on cetaceans’ health.

In this study, we tested two mother-calf pairs of bottlenose dolphins in a helping task. Specifically, we provided dolphins with an enrichment tool based on the rope-pulling task paradigm to obtain a resource. The calves were unable to solve the task and get the resource on their own, and then we evaluated whether their mothers helped them. Moreover, we also evaluated whether the social bond strength among mother and calf, measured with the simple ratio index, may play an important role in determining altruistic behaviors. Our findings show that mothers performed altruistic behaviors toward their calves only when they had a strong social bond with them. Indeed, only a mother had a strong social bond with her calf, and only she acted altruistically. Moreover, as her calf grew, their social bond weakened and the mother stopped performing altruistic behaviors. As a result, our data seem to suggest the strength of social bonds has an important role in determining altruism. [ABSTRACT FROM AUTHOR]

Stable isotope analysis (SIA) provides ecological data that can be safely and efficiently collected on endangered, threatened, and cryptic species. Marine mammals are an ecologically important group for which economical and logistical constraints can make data collection challenging. Stranded marine mammals are often used in research, but the causes of strandings and subsequent tissue decomposition could affect SIA. We conducted a three‐part study to test the validity of using δ13C and δ15N values from tissues of stranded bottlenose dolphins (Tursiops truncatus) and West Indian manatees (Trichechus manatus) for ecological studies. First, we quantified isotopic overlap using ellipses based on 95% of the data to compare isotope values in skin between stranded and live‐captured animals. Second, we compared stable isotope values from liver, skin, and muscle of animals that had stranded and were sampled at different decomposition stages. Third, we experimentally exposed each tissue to environmental conditions and sampled tissues as they decomposed. For both dolphins and manatees, isotopic ellipses from skin of stranded carcasses were similar to live‐captured individuals. Among individuals recovered at different decomposition stages, more advanced decomposition affected δ13C values in dolphin liver and skin but not in manatee tissues and had no effect on δ15N values in any tissue for either species. In the experimental manipulation, decomposition resulted in depleted δ13C values, enriched δ15N values, and increased C:N in liver for both species. Skin and muscle from stranded dolphins and manatees are representative of their corresponding live populations and can be used for SIA with appropriate caution. To facilitate the use of tissues from stranded animals, tissues should be dried or frozen for storage as soon as possible after sampling. We recommend liver from stranded animals only be used for SIA when researchers need tissues with short turnover times and can access fresh samples. Without consideration of decomposition effects on isotope values, ecologists may make inaccurate inferences about habitat use, diet, and community structure. Careful use of SIA on tissues from stranded animals can help researchers provide better quality information for managers and policy makers. [ABSTRACT FROM AUTHOR]

Simple Summary: Cognitive foraging enrichment is not commonly provided to dolphins in zoos, and research with other species suggests the potential for significant welfare benefits. We provided 11 bottlenose dolphins (Tursiops truncatus) at Kolmårdens Djurpark with alternating weeks of only cognitive enrichment, or only non-cognitive enrichment devices over an 8-week study period while recording data from several multidimensional welfare-related parameters. We found that the dolphins were more engaged by cognitive enrichment items, both when measured through qualitative caretaker scores and quantitative behavioural observations. We also found longer term welfare-related changes: during cognitive enrichment weeks, dolphins were more motivated for training sessions, and showed less anticipatory and stereotypic behaviour. We recommend that goal-oriented cognitive foraging enrichment is prioritised by dolphin facilities, and discuss how this might best be achieved in practice. Bottlenose dolphins are the most common cetacean kept globally in zoos and aquaria (hereafter zoos), and are gregarious animals with a mostly opportunistic, generalist feeding strategy in the wild. In zoos, they have limited to no opportunities to express natural foraging behaviours as they receive their daily food ration of dead fish in a series of training sessions. Enrichment provision has increased in recent years, but items are still predominantly simple and floating in nature, and do not always target the animals' problem-solving or food-acquisition behaviours. These discrepancies run concurrently with the intense debate about dolphin welfare in zoos and how to improve it. The current study used a within-subject design on 11 bottlenose dolphins at Kolmårdens Djurpark and measured how several welfare indicators differed between two treatments of "cognitive" and "non-cognitive" food-based enrichment. The treatments were provided on an alternating basis for eight consecutive weeks: during cognitive enrichment weeks, the animals received items which stimulated their problem-solving and foraging behaviours, and during non-cognitive enrichment weeks, they received simple items paired with fish (to eliminate bias due to food value). Data were taken related to several multidisciplinary welfare parameters during enrichment provision and training sessions, and to activity budget behaviours throughout the week. During the cognitive as opposed to non-cognitive enrichment weeks, the dolphins engaged more with the enrichment, were more motivated to participate in training sessions and performed less anticipatory and stereotypic behaviours, suggesting that cognitive enrichment improved several indicators of bottlenose dolphin welfare. Valuable lines of further investigation would be to understand how individual differences and different types of cognitive enrichment impact potential welfare benefits. Our results suggest that enrichment items promoting cognitive foraging behaviours may improve dolphin welfare, and therefore zoos might prioritise giving cognitive enrichment to this species as well as considering the same for other species with similar cognitive skills and foraging ecologies. [ABSTRACT FROM AUTHOR]

Atlantic bottlenose dolphins (Tursiops truncatus) are frequently observed in the coastal waters of Palm Beach County, Florida. In this study, markrecapture surveys using photo-identification techniques were used to estimate population abundance of Atlantic bottlenose dolphins in this area for the first time. Surveys were conducted for 11 years, between 2005 and 2016, during which 384 individuals were identified and catalogued from distinctive nicks and notches on their dorsal fins. Each marked individual was documented an average of 2.4 times (range 1 to 19). Low resighting rates and a constant rate of encounter with previously unmarked individuals suggest that the population is open, comprising both residents and transients. The Jolly-Seber method was used to estimate population abundance. Estimates of abundance varied greatly in time with an overall average of 264 individuals and a 95% confidence interval of 162 to 366 (SE = 51.3), indicating a variable population size. As threats in the region continue to rise, such as overfishing, toxic algae blooms, and environmental pollutants, this understudied population may be vulnerable to decline. A better understanding of the population dynamics could facilitate more effective conservation action. [ABSTRACT FROM AUTHOR]

Abstract Stable isotope analysis (SIA) provides ecological data that can be safely and efficiently collected on endangered, threatened, and cryptic species. Marine mammals are an ecologically important group for which economical and logistical constraints can make data collection challenging. Stranded marine mammals are often used in research, but the causes of strandings and subsequent tissue decomposition could affect SIA. We conducted a three‐part study to test the validity of using δ13C and δ15N values from tissues of stranded bottlenose dolphins (Tursiops truncatus) and West Indian manatees (Trichechus manatus) for ecological studies. First, we quantified isotopic overlap using ellipses based on 95% of the data to compare isotope values in skin between stranded and live‐captured animals. Second, we compared stable isotope values from liver, skin, and muscle of animals that had stranded and were sampled at different decomposition stages. Third, we experimentally exposed each tissue to environmental conditions and sampled tissues as they decomposed. For both dolphins and manatees, isotopic ellipses from skin of stranded carcasses were similar to live‐captured individuals. Among individuals recovered at different decomposition stages, more advanced decomposition affected δ13C values in dolphin liver and skin but not in manatee tissues and had no effect on δ15N values in any tissue for either species. In the experimental manipulation, decomposition resulted in depleted δ13C values, enriched δ15N values, and increased C:N in liver for both species. Skin and muscle from stranded dolphins and manatees are representative of their corresponding live populations and can be used for SIA with appropriate caution. To facilitate the use of tissues from stranded animals, tissues should be dried or frozen for storage as soon as possible after sampling. We recommend liver from stranded animals only be used for SIA when researchers need tissues with short turnover times and can access fresh samples. Without consideration of decomposition effects on isotope values, ecologists may make inaccurate inferences about habitat use, diet, and community structure. Careful use of SIA on tissues from stranded animals can help researchers provide better quality information for managers and policy makers.

Interactions between bottlenose dolphins (Tursiops truncatus) and fishing gear have negative impacts on both dolphins and fisheries. Therefore, the damage and economic loss caused to the purse seine fishery were evaluated on a spatio-temporal scale, and the catch composition was addressed. Face-to-face interviews were conducted with the fishers, and observations aboard the boat were recorded between August 2018 and July 2019 in the M'diq region, northwestern Morocco. Throughout the study period, the frequency of fishing trips attacked by bottlenose dolphins was 44.75% (n=324), and the catch damage was 33%. In addition, depredated fishing operations were significantly lower in CPUE than unattacked ones. The total mending cost was 35,533.3$, with a difference between months and seasons. Bottlenose dolphins (Tursiops truncatus) attacked 32.2% of the fishing operations. However, this frequency of fishing operations depredated by depth was not significant. The current study proved that these interactions inflict substantial economic losses on the fishers of this region. [ABSTRACT FROM AUTHOR]

This study is the first baseline acoustic description of common bottlenose dolphin populations (Tursiops truncatus) from Revillagigedo Archipelago and the first identification of signature whistles (SWs) in an oceanic population of T. truncatus. A total of 85% (199/233) of the recorded whistles were classified as stereotyped whistles and subsequently (bout analysis/SIGID) categorized into one of five SW types. External observers were in perfect agreement in classifying whistles into the adopted SW categorization. SWs represented 42% (98/233) of the repertoire. Overall, most whistle types were categorized as sine (80%; SW1, SW2, SW4, and SW5) with one downsweep (20%, SW3). Roca Partida Island had the highest number of SW types. Principal component analysis explained 77% of the total SWs variance, highlighting the importance of shape/contour variables to the SWs variance. The combined mean SWs acoustic parameters from Revillagigedo Archipelago were higher than that recorded in coastal regions, which may indicate there are differences between SWs of pelagic and coastal populations. However, further acoustic and ecological studies in the Archipelago are needed to clarify and expand our findings, to identify its members (Photo ID and SW Revillagigedo Catalog), and to investigate this topic at other oceanic islands. [ABSTRACT FROM AUTHOR]

For dolphins, the strongest bond documented is typically that between a mother and her pre-weaned offspring, but outside of the maternal relationship, our knowledge of calf behavior is limited. We examined how 23 bottlenose dolphin (Tursiops truncatus) calves (11 females and 12 males from 9 matrilines) initiated pectoral fin contact (PFC) exchanges with their mothers and kin (n = 362) versus with non-kin (n = 950). Calves initiated PFC exchanges with preferred partners (primarily their mothers) over individuals who were simply available to them. For calves with mothers as their only kin available, there was a difference in how they shared PFC with non-kin adults versus non-kin young. A calf was twice as likely to initiate PFC with an adult (mother or adult non-kin) as with another young dolphin. Male and female calves were different in how they initiated PFC with kin and non-kin, which supports previous research that identified a sex difference in calf behavior. These results support the observation that kin and non-kin dolphins share PFC differently. It is also likely that kin (mothers and calves, siblings, etc.) use other forms of contact to share information and potentially develop their relationships. Understanding all types of tactile contact would facilitate a more detailed understanding of how touch might be used by dolphins when relationships are established and maintained.

Social structuring from assortative associations may affect individual fitness, as well as population-level processes. Gaining a broader understanding of social structure can improve our knowledge of social evolution and inform wildlife conservation. We investigated association patterns and community structure of female Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia, assessing the role of kinship, shared culturally transmitted foraging techniques, and habitat similarity based on water depth. Our results indicated that associations are influenced by a combination of uni- and biparental relatedness, cultural behaviour and habitat similarity, as these were positively correlated with a measure of dyadic association. These findings were matched in a community level analysis. Members of the same communities overwhelmingly shared the same habitat and foraging techniques, demonstrating a strong homophilic tendency. Both uni- and biparental relatedness between dyads were higher within than between communities. Our results illustrate that intraspecific variation in sociality in bottlenose dolphins is influenced by a complex combination of genetic, cultural, and environmental aspects. [ABSTRACT FROM AUTHOR]

Fisheries constitute a major threat to marine mammals globally. To evaluate the impact of small-scale fisheries (SSF) on regional under-studied marine mammal populations, we tested a novel and cost-effective approach at three data-limited locations of the central and eastern Mediterranean Sea. Using off-the-shelf GPS loggers to track SSF activities and systematic surveys to map the distribution of marine mammals, we assessed the probability of co-occurrence between SSF and marine mammals by reporting areas of spatial overlap. Spatial overlap between SSF and the core zones of marine mammal distribution (ranging between 21.85–35.4%) was observed in all three locations, indicating potential interaction hotspots. The probability of co-occurrence in those areas varied from 0.5–2.9% depending on the species. The resulting overlap between fishing activity and marine mammals may pose a threat in both directions: higher risk of species entanglement and economic burden on fishers due to gear damage. Despite the spatial and temporal limitations of this pilot study, the proposed approach can provide baseline information on SSF-marine mammal co-occurrence, particularly in financially limited regions. If applied on a larger scale, our method may be used to inform future conservation actions with the aim to reduce pressure on key populations. [ABSTRACT FROM AUTHOR]

The distribution of common bottlenose dolphins Tursiops truncatus is associated with environmental factors, which influence morphological adaptations. In the present study, we examined the cranial characteristics of this species from the Pacific Northwest of Mexico to detect the main variations using geometric morphometric analysis. From stable isotope concentrations (δ13C), we identified 24 specimens of the inshore coastal ecotype and 18 of the offshore ecotype. Maturity was determined using the degree of fusion of the maxillae and premaxillae. Allometry was detected in the skull lateral region, indicating that the relationship between shape and size is maintained in adults. After eliminating the allometric effect by discarding the smallest individuals, morphometric comparisons indicated differences between the ecotypes that were associated mainly with the intersection between the frontal bone and zygomatic process, the anteriormost point in the curvature of the zygomatic process, and the meeting of the suture between squamosal and exoccipital bones, with the supramastoid crest to anteriormost in the curvature of the temporal crest of the intersection between the parietal and interparietal. No significant differences were found in the ventral view. The cranial differences between both Tursiops truncatus ecotypes could be mainly associated with the different types of feeding. [ABSTRACT FROM AUTHOR]

Lateralization of behaviors and information processing are common across species. Hypothesized to be crucial for more efficient responding to environmental stimuli, lateralization has been investigated for a number of topics. Cetaceans are proposed to be hemispheric specialists, given a small corpus callosum, complete decussation of the optic nerve, and the ability to respond to a different visual stimulus presented to each eye simultaneously. Research with cetaceans has shown strong biases in a number of behaviors, including swimming, foraging, social interactions, and responses to myriad visual stimuli. Given similar evolutionary pressures, different species of cetaceans should display similar lateralized preferences. Previous research with bottlenose dolphins in managed care and wild striped dolphins indicated a right eye preference when viewing unfamiliar objects. The purpose of the current study was to evaluate the eye preference of belugas, bottlenose dolphins, and Pacific white-sided dolphins (lags) in managed care when viewing familiar and unfamiliar objects. The results from 11 belugas, 5 bottlenose dolphins, and 5 lags indicated that consistent group level eye preferences were not present. The belugas preferred to view both types of objects with both eyes, with the majority of the belugas showing a left-eye preference when a monocular gaze was used. Bottlenose dolphins tended to view both objects with their right eye while lags used their left eye when viewing objects. These results may have been affected by viewing objects below water versus above water. The belugas and the Pacific white-sided dolphins were able to view the objects below water, which may have elicited more naturalistic visual examinations of the objects (i.e., greater ecological validity). Viewing objects within one’s habitat may facilitate the discrimination of an object rather than simply its detection, which is may be more likely when encountering stimuli above the surface of the water as the bottlenose dolphins had to do in the present and past research. Future research should compare if presentation of the stimulus above water versus below water affects the eye preference displayed.

Adult bottlenose dolphins share pectoral fin contacts (PFC) to manage their social relationships but less is known about how mothers share PFC with their calves. Using a dataset collected over 16 years, we analyzed how 10 matrilines, including three second generation female dolphins in a maternal role, used PFC with their pre-weaned calves. Mothers had different rates of initiation with their calves forming a continuum from those initiating few contacts (15%) to those initiating more (44%). For mothers with all-aged calves, the lateral side was contacted the most to start interactions with mothers contacting body parts at a similar rate. All mothers assumed the same posture regardless of their role as initiator or receiver, with horizontal the most prevalent posture. Two maternal styles were found for PFC: high and low use of PFC. Within the high PFC group, there was individual variation that was related to calf sex. Even though evidence of maternal style was confirmed in PFC exchanges between adult female dolphins and their calves, the number of PFC shared between these kin was only ~9% of all documented PFC contacts (N = 4,345) over 16 years, suggesting that other forms of tactile contact may be more important within the confines of the mother-offspring relationship in delphinids.

Levels of boat traffic in coastal seas have been steadily increasing in many parts of the world, introducing pressures on marine wildlife through disturbance. The appropriate management of human activities is important not only to preserve wildlife, but also for the local communities that depend on ecotourism for employment and their economy. This study presents further insight into bottlenose dolphin (Tursiops truncatus) responses to boats in New Quay Bay (West Wales) within the Cardigan Bay Special Area of Conservation. This region is heavily dependent on wildlife tourism, and marine traffic is regulated through a long-standing Code of Conduct. Based on a long-term dataset spanning the months of April to October and the years 2010–2018, the study found that compliance to a code of human behaviour increased dolphin positive responses towards boats. Dolphin responses to individual named boats and to different boat types were examined in greater detail. Speed boats, small motorboats, and kayaks were found to break the code most often, resulting in higher rates of negative response by dolphins. Visitor passenger boats formed the majority of boat traffic in the area, and showed greater compliance than other general recreational crafts. Suggestions are made for the better protection of the coastal dolphin population, as well as the role that citizen science can play to help achieve this goal through working directly with wildlife trip boats and the recruitment of local observers. [ABSTRACT FROM AUTHOR]