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Highlights • Under human care dolphins use echolocation towards immersed non-alimentary objects. • Acceleration of the Inter-Click-Interval (ICI) in approach phase. • ICI deceleration before touch of the object takes over from echolocation. • No sound production while contact lasts. Abstract Odontocetes modulate the rhythm of their echolocation clicks to draw information about their environment. When they approach preys to capture, they speed up their emissions to increase the sampling rate of "distant touch" and improve information update. This global acceleration turns into a "terminal buzz" also described in bats, which is a click train with drastic increase in rate, just as reaching the prey. This study documents and analyses under human care bottlenose dolphins' echolocation activity, when approaching non-alimentary targets. Four dolphins' locomotor and clicking behaviours were recorded during training sessions, when sent to immersed objects pointed by their trainers. Results illustrate that these dolphins profusely use echolocation towards immersed non-alimentary objects. They accelerate click emission when approaching the target, thus displaying a classical terminal buzz. However, their terminal buzz slackens off within a quarter of second before the end of click train. Typically, they decelerate to stop clicking just before they touch the object using their rostrum lower tip. They do not emit clicks as the contact lasts. In conclusion, when exploring inert objects, bottlenose dolphins under human accelerate clicking like other odontocetes or bats approaching preys. Bottlenose dolphins' particular slackening-off profile at the end of the buzz shows that they anticipate the moment of direct contact, and they stop just as real touch relays distant touch of the object. [ABSTRACT FROM AUTHOR]

Cognitive bias tests measure variation in emotional appraisal and are validated methods to assess animals’ affective states. However, the link between social behaviours and cognitive bias has not yet been investigated. Bottlenose dolphins are a gregarious species for whom welfare research is increasing in importance, and thus are a good model to test such an association. We adapted a spatial location judgement bias test for eight captive bottlenose dolphins to investigate the link between cognitive bias and social behaviour, where we conducted behavioural observations outside of training sessions and did not experimentally induce an affective state. Subjects showed stable individual differences in cognitive biases across the three test days. Furthermore, dolphins showing more synchronous swimming, a fundamental affiliative behaviour, judged ambiguous cues significantly more optimistically. Our longer-term data showed cognitive bias and synchronous swimming frequency were significantly associated for up to two months preceding the test, but disappeared prior to that, suggesting that here cognitive bias differences were reflected by transitory affective states rather than longer-term traits. We hypothesise that the frequency of synchronous swimming may induce affective states and/or be induced by them; either way, it has strong potential as an indicator of affective state in this species and beyond. [ABSTRACT FROM AUTHOR]

• During training sessions, bottlenose dolphins are visually left lateralized. • They display more emotional reactions when negative stimuli are first presented on their left than right side. • Visual and motor laterality appears to be a potential indicator for future dolphin welfare assessment. Hemispheric lateralization is a specialized neural and cognitive processing achieved preferentially by either the left or the right hemisphere of the brain. Among vertebrates, emotions processing seems to be lateralized, but the involvement of each hemisphere is still on debate. Our study investigated visual and motor laterality on five bottlenose dolphins' (Tursiops truncatus) during spontaneous and experimentally induced emotional contexts. We measured motor laterality in pectoral used and swimming position during positive social interactions. Additionally, during training sessions, stimuli with positive or negative emotional valences were presented either on the dolphins' left or right side. Emotional reactions toward stimuli were measured and a visual laterality index was calculated. Dolphins were visually left-lateralized during training sessions. They also reacted more when negative stimuli were presented on their left side than right side during the first stimuli presentation. Our results suggest that bottlenose dolphins, like other vertebrates, may present a right hemisphere dominance for social information processing, detection of and response to unpredictable or novel stimuli and a left-hemisphere dominance during escape responses inhibition. Further studies on a larger sample size should explore inter-individual variation and identify other potential contexts in which lateralization emerges. Emotional lateralization should be considered as a potential indicator for future dolphin welfare assessment. [ABSTRACT FROM AUTHOR]

Anticipatory behaviour describes the actions taken to prepare for an upcoming event. Bottlenose dolphins ( Tursiops truncatus ) in captivity are known to display anticipatory behaviours before feeding sessions, but it is unknown whether they would anticipate non-alimentary events. Furthermore, there is no published information available for any species on whether the level of anticipatory behaviour is predictive of an animal’s actual participation in the following event or reward: answering this question would bring us closer to understanding this behaviour and its related affective states. In this study, we used sound cues to condition dolphins to the arrival of toys in their pool or a positive Human-Animal Interaction (HAI) with a familiar trainer, and measured their anticipatory behaviour before each event. The protocol was validated since the dolphins performed significantly more anticipatory behaviour before the toys and HAI contexts than a control situation, by means of increased frequencies of surface looking and spy hopping. Furthermore, we found that dolphins showed more anticipatory behaviour before the HAI than the toys context (Linear Mixed Model with 1000 permutations, all P <  0.001). In the second part of the investigation, higher anticipatory behaviour before toy provision, HAIs, and feeding sessions was significantly correlated to higher levels of participation in the event itself (measured by time spent with humans/toys, and number of times dolphins left during feeding sessions; LMM with 1000 permutations, respectively: β  = 0.216 ± 0.100 SE, P  = 0.039; β  = 0.274 ± 0.097 SE, P  = 0.008; β  = −0.169 ± 0.080 SE, P  = 0.045). Our results suggest that toys and HAIs were perceived as rewarding events, and we propose that non-food human interactions play an important role in these animals’ lives. We also provide some of the first empirical evidence that anticipatory behaviour is correlated to the level of participation in the following event, supporting anticipatory behaviour as a measure of motivation, and hope that this stimulates further work regarding the use of this behaviour to assess and improve animal welfare. [ABSTRACT FROM AUTHOR]

Nature-based tourism has surged in recent years with the desire for up-close interactions and "connections" with wild animals. The conservation value, animal welfare considerations, visitor satisfaction, and profitability of wildlife tourism are often in direct conflict with trade-offs commonly accepted. In this paper, we reviewed more than four decades of literature on the deleterious behaviors and risks documented during close tourist and other recreational interactions between humans and free-ranging dolphins and encounters between humans and lone, sociable dolphins. Our compilation provides a geographical, chronological, and qualitative overview of these encounters, reviews both humans' and dolphins' deleterious behaviors during interspecific interactions and summarizes the main risks to both humans and dolphins during close encounters. Based on this review, we outline and discuss how both animal welfare and human safety should be managed such that these activities are sustainable; the demand for personal wildlife experiences continues to grow at an alarming rate and the economic pressures placed on wild animal populations run the risk of damaging the very environmental assets that support this industry if they cannot be managed effectively. • The desire for close-up interactions with iconic species has boomed in recent years. • Geographical and chronological content is reviewed for human-dolphin close encounters. • Human intrusive behaviors toward dolphins are documented most. • Increased dolphin tolerance is associated with a high risk of deleterious outcome. • Animal welfare and human safety should be managed in sustainable activities. [ABSTRACT FROM AUTHOR]

Temperament, i.e. consistent inter-individual differences in behavior, has been documented in many species. Especially, boldness-shyness continuum is the ecologically relevant trait most frequently used to describe temperament among species. Reactions along the bold-shy axis demonstrate an organism's ability to cope with environmental conditions and reflect its response to environmental stress. Our study investigated the existence of boldness-shyness continuum in 16 captive Antillean manatees (Trichechus manatus manatus) housed in 2 zoological parks. We first aimed to establish a valid methodology to measure boldness and shyness using behavioral tests. Additionally, our study explored 2 other potential temperament dimensions: sociality and reactivity to humans, and their association with boldness. Finally, since animals were kept under human care, we investigated human perception on manatees' temperament. We conducted behavioral tests i.e. novelty tests involving novel objects, a novel sound, and an unfamiliar human. We recorded behaviors related to exploration as well as social interactions (i.e. physical proximity, social contacts) and we assessed manatees' reactivity to humans through a participation score during hand-feeding sessions. Finally, we collected keepers' subjective impression about individuals' temperament through traits rating method. To our knowledge, this is the first paper that tested manatees' reactions to different novel stimuli in order to determine their temperament. Our results first allowed us to identify the most relevant stimuli and variables to measure boldness and to classify individuals as bolder or shier. Individuals characterized as bolder displayed significantly more approach, longer approach and more contact toward stimuli than shier individuals. Moreover, boldness score was significantly associated with physical proximity with conspecifics, as well as with the participation score to hand-feeding sessions in one zoo. Finally, surveys completed by keepers were reliable and positive associations were found between rated items and behavioral observations. These findings support that as many species, manatees demonstrate boldness-shyness traits. More investigations on a larger sample size are needed to explore manatees' temperament dimensions, and how these traits could modulate their interactions with their conspecifics and their environment. Studying manatees' temperament could help improving the management and welfare of the species under human care. It could also facilitate their management in wildlife reserves by understanding manatees' movements and evaluate the anthropogenic impact on wild populations. • Manatees have bold or shy personality • Boldness score was positively associated with social proximity and reactivity to keepers • Keepers' surveys were reliable and some traits were consistent with behavioral observations • Novelty test seems to be an efficient tool to measure boldness in manatees [ABSTRACT FROM AUTHOR]

• Three bottlenose dolphins were asked to perform synchronised jumps in tandem. • While jumping in tandem, click trains were emitted by only one individual 98% of times. • The dolphins that do not vocalize are probably synchronising their jumps by eavesdropping the clicking dolphin. Synchronous behaviours occur when two or more animals display the same behaviour at the same time. However, the mechanisms underlying this synchrony are not well understood. In this study, we carried out an experiment to determine whether or not Bottlenose dolphins use acoustic cues when performing a known synchronised exercise. For this, we recorded three dolphins while they performed requested aerial jumps both individually or synchronously in pairs, with a hydrophone array and a 360° underwater video camera allowing the identification of the subject emitting vocalisations. Results indicated that in pairs, dolphins synchronised their jumps 100% of the time. Whether they jumped alone or in pairs, they produced click trains before and after 92% of jumps. No whistles or burst-pulsed sounds were emitted by the animals during the exercise. The acoustic localisation process allowed the successful identification of the vocalising subject in 19.8% of all cases (N = 141). Our study showed that in all (n = 28) but one successful localisations, the click trains were produced by the same individual. It is worth noting that this individual was the oldest female of the group. This paper provides evidence suggesting that during synchronous behaviours, dolphins use acoustic cues, and more particularly click trains, to coordinate their movements; possibly by eavesdropping on the clicks or echoes produced by one individual leading the navigation. [ABSTRACT FROM AUTHOR]

• Dolphin communication relies mainly in the acoustic channel. • The aim of this study was to determine if there was a correlation between the non-signature whistle production and the underwater behaviors of a group of bottlenose dolphins. • The occurrences of the six categories of whistles were highly collinear. • Non-signature whistle production was positively correlated with the time individuals spent slow swimming alone and negatively with the time spent in affiliative body contact. Bottlenose dolphins are social cetaceans that strongly rely on acoustic communication and signaling. The diversity of sounds emitted by the species has been structurally classified into whistles, clicks and burst-pulsed sounds. Although click sounds and individually-specific signature whistles have been largely studied, not much is known about non-signature whistles. Most studies that link behavior and whistle production conduct aerial behavioral observations and link the production of whistles to the general category of social interactions. The aim of this study was to determine if there was a correlation between the non-signature whistle production and the underwater behaviors of a group of bottlenose dolphins (Tursiops truncatus) under human care, during their free time in the absence of trainers. To do this we made audio-video recordings 15 min before and after 10 training sessions of eight dolphins in Boudewijn Seapark (Belgium). For the behavioral analysis we conducted focal follows on each individual based on six behavioral categories. For the acoustical analysis, carried out at the group level, we used the SIGID method to identify non-signature whistles (N = 661) and we classified them in six categories according to their frequency modulation. The occurrences of the six categories of whistles were highly collinear. Most importantly, non-signature whistle production was positively correlated with the time individuals spent slow swimming alone, and was negatively correlated with the time spent in affiliative body contact. This is the first analysis that links the production of non-signature whistles with particular underwater behaviors in this species. [ABSTRACT FROM AUTHOR]