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Carrying of dead calves by free-ranging Texas bottlenose dolphins (Tursiops truncatus)

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  • Ziphius EcoServices
... Epimeletic behavior occurs when 1 or more individuals assist other distressed, injured, dying, or deceased conspecifics (Caldwell and Caldwell 1966). This behavior has been reported for several cetacean species, in both captive and wild populations, such as Risso's dolphin, Grampus griseus (Palacios and David 1995); rough-toothed dolphin, Steno bredanensis (Lodi 1992;Ritter 2007;de Moura et al. 2009); tucuxi, Sotalia fluviatilis (Santos et al. 2000); long-beaked common dolphin, Delphinus capensis (Park et al. 2012); La Plata river dolphin, Pontoporia blainvillei (Cremer et al. 2006); bottlenose dolphin, Tursiops truncatus (Cockcroft and Sauer 1990;Harzen and dos Santos 1992;Fertl and Schiro 1994;Kurimoto 2003;Kuczaj et al. 2015); and Atlantic spotted dolphin, Stenella frontalis (Hering 1996;Alves et al. 2015). The direct aid-provider is typically 1 or more individuals, with the aiding individual (referred to as the supporter) providing assistance using the melon, rostrum, or the leading edge of the dorsal fin (Fertl et al. 1994). ...
... This behavior has been reported for several cetacean species, in both captive and wild populations, such as Risso's dolphin, Grampus griseus (Palacios and David 1995); rough-toothed dolphin, Steno bredanensis (Lodi 1992;Ritter 2007;de Moura et al. 2009); tucuxi, Sotalia fluviatilis (Santos et al. 2000); long-beaked common dolphin, Delphinus capensis (Park et al. 2012); La Plata river dolphin, Pontoporia blainvillei (Cremer et al. 2006); bottlenose dolphin, Tursiops truncatus (Cockcroft and Sauer 1990;Harzen and dos Santos 1992;Fertl and Schiro 1994;Kurimoto 2003;Kuczaj et al. 2015); and Atlantic spotted dolphin, Stenella frontalis (Hering 1996;Alves et al. 2015). The direct aid-provider is typically 1 or more individuals, with the aiding individual (referred to as the supporter) providing assistance using the melon, rostrum, or the leading edge of the dorsal fin (Fertl et al. 1994). However, in instances where multiple individuals (referred as multi-individual scenarios) are involved, they are more likely to fall into formation to provide aid (Park et al. 2012;Kuczaj et al. 2015). ...
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Several cetacean species have demonstrated epimeletic behavior that relies on the tight social bonds between conspecifics. These ehaviors and the corresponding vocalizations were recorded during a rare encounter with a group of Indo-Pacific humpback dolphins (Sousa chinensis) that included a presumed mother and deceased calf, in Sanniang Bay, China. The observed dolphins were divided into 2 apparent groups: 1) a central group with the presumed mother and her deceased calf, along with 1 to 6 other individuals swimming in synchrony with the presumed mother; and 2) a following group of several individuals, dispersed over varying distances from approximately 20 to > 300 m, that swam in the same direction as the central group. The mother was seen mostly supporting the calf’s body using her back, anterior to the dorsal fin and posterior to the melon, while the other members of the central group exhibited standing-by behaviors (i.e., remaining close to the deceased calf but not providing aid). Whistles in this context were of a longer duration and a higher complexity in the frequency modulation compared to social contexts. Several whistle types were also repeated frequently. This paper provides a detailed description of epimeletic behavior and the whistles possibly associated with that behavior in an endangered population of Indo-Pacific humpback dolphins.
... The supporter may often be accompanied by other individuals, called "escorts", who either directly assist the caregiver interacting with the receiver or remain close and swim by the pair [5,8]. Post-mortem supportive behavior in cetaceans generally includes stereotyped behaviors that can be divided into three main groups: (1) standing-by, with individuals remaining close to the carcass without directly interacting with it, (2) excitement, with participants showing behaviors typical of arousal states such as erratic swimming, and (3) supportive behavior, with individual interacting directly with the carcass, typically lifting, sinking or carrying it with the melon, the rostrum, or the edge of the dorsal fin [9,10]. ...
... Indeed, nurturant behavior has been proposed to derive from the disruption of the strong social bond that links a mother to its offspring [4] and from the interruption of the maternal cares [11]. This could be especially true for species in which females are the main caregivers of the offspring which is the case for bottlenose dolphins [10]. Mothers care for their offspring for the first 3-4 years of life (e.g., [35]) nursing, protecting, playing with, and maintaining proximity to their calves [36]. ...
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Epimeletic behavior toward dead calves has been frequently reported in cetaceans, mostly with females (presumed mothers) showing supportive behaviors such as carrying, lifting, or sinking, often assisted by “escort” individuals. However, information on acoustic production in such contexts is scarce. This report describes two observations of epimeletic behavior toward dead newborns in bottlenose dolphins and associated acoustic production. Data were collected at the Tiber River estuary (Rome, Mediterranean Sea, Italy) with one hydrophone for passive acoustic monitoring and two digital cameras. In both cases, an individual (presumed mother) acting as the main supporter and directly interacting with the carcass by lifting it (case 1) or sinking it (case 2) was observed. Another adult individual (escort) was present in both encounters showing standing-by and excitement behaviors (case 1) and supportive behavior (case 2). In both encounters, whistles, pulsed sounds, and bray-call elements were recorded. The consistent vocal activity observed likely conveyed context-specific information. A signature whistle in the first encounter was also recorded, likely emitted by the putative mother as a distress call. This report confirms the occurrence of epimeletic behavior in bottlenose dolphins and reports a preliminary description of the acoustic production when a dead calf is involved, providing additional information on this largely unknown topic.
... While the behavioral responses of delphinids towards dead and dying conspecifics have only been documented in 10 of the 42 delphinid species: Atlantic spotted dolphins (Stenella frontalis; Alves et al., 2015), Australian humpback dolphins (Sousa sahulensis; Reggente et al., 2016), bottlenose dolphins (Tursiops truncatus; Diaz Lopez, 2020), Indo-pacific bottlenose dolphins (Tursiops aduncus; Reggente et al., 2016), Indo-pacific humpback dolphins (Sousa chinesis; Bearzi et al., 2018), killer whales (Orca orcinus; Reggente et al., 2016), long-beaked common dolphins (Delphinus capensis; Park et al., 2013), Risso's dolphins (Grampus griseus; Reggente et al., 2016), short-finned pilot whales (Globicephala macrohynchus; Reggente et al., 2016), and spinner dolphins (Stenella longirostris; Reggente et al., 2016); and yet, these behavioral responses are still poorly understood (Reggente et al., 2016). Previously, behavioral responses towards dead conspecifics have been attributed to epimeletic behavior (Alves et al., 2015;Caldwell & Caldwell, 1966;Cockcroft & Sauer, 1990;Connor & Smolker, 1990;Fertl & Schiro, 1994;Harzen & Santos, 1992;Kilborn, 1994;Lodi, 1992;Santos et al., 2000;Smith & Sleno, 1986), grief (Bearzi et al., 2018), mate-guarding (Dudzinski et al., 2003), infanticide (Dunn et al., 2002;Diaz Lopez et al., 2018;Patterson et al., 1998;Towers et al., 2018), empathy (Frohoff, 2011;Kuczaj et al., 2001;Nakahara et al., 2016;Perez-Manrique & Gomila, 2018;Reggente et al., 2016), inclusive fitness (Bearzi et al., 2017), and personality (Diaz Lopez, 2020; Kuczaj et al., 2012). ...
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Cetacean behavior has long attracted scientific attention as humans endeavor to discover what makes these mammals so emotive and engaging. To date, much of this research has focussed on abundant and widely distributed cetacean species such as bottlenose dolphins (Tursiops truncatus) and humpback whales (Megaptera novaeangliae). As an endangered and often evasive species, research regarding Irrawaddy dolphin (Orcaella brevirostris) behavior is limited. This study uses data collected by The Cambodian Marine Mammal Conservation Project, to investigate the behavioral responses of Irrawaddy dolphins towards a dead conspecific. During a routine boat survey of Cambodia's Kep Archipelago, the carcass of an adult female Irrawaddy dolphin was recovered and attached to the stern of the research vessel and promptly towed to the research island for further examination. During this survey, there was a four-fold increase in the number of Irrawaddy dolphin groups observed compared to the seasonal average (post-monsoon), in addition to an atypically positive response towards the research vessel and an atypical increase in the number of behavioral events observed. These behavioral variations were believed to be in response to the towed dead conspecific. The authors propose future dedicated research to assess the complexity of wild Irrawaddy dolphin behavior, cognition, and awareness to robustly exemplify the species' apparent sentience and intelligence.
... Similar behavior has been recorded for other marine mammals from all over the world. The behavior was also reported in bottlenose dolphins (Tursiops truncates) (Cockcroft and Sauer, 1990;Harzen and dos Santos, 1992;Fertl and Schiro, 1994;Dudzinski et al., 2003;Kuczaj et al., 2015); rough toothed dolphins (Steno bredanensis) (Lodi, 1992;Ritter, 2007;de Moura et al., 2009); long-beaked common dolphins (Delphinus capensis) (Park et al., 2013); Atlantic spotted dolphin (Stenella frontalis) (Herzing, 1996;Alves et al., 2015); and Risso's dolphins (Grampus griseus) (Palacios and David, 1995). Reggente et al. (2016) described observations of adults carrying dead calves and juveniles in 7 odontocetes (toothed cetaceans) species including Indo-Pacific bottlenose dolphins (Tursiops aduncus), Spinner dolphins (Stenella longirostris), Killer whales (Orcinus orca), Australian humpback dolphins (Sousa sahulensis), Sperm whales (Physeter macrocephalus) and Shortfinned pilot whales (Globicephala macrorhynchus) as well as Risso's dolphins (Grampus griseus). ...
... PAB could therefore be an extension of kin recognition 43 and kin survival 35,44 . Evolutionarily, PAB could also be an emotional response of mothers unable to comprehend the death of their offspring 19,45 . This argument is supported by observations in captivity where upon the removal of a dead infant from the enclosure the mothers have taken an inanimate surrogate 46,47 . ...
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Postmortem attentive behaviour (PAB) has been rec- orded across several mammalian species. Here, we document two instances of PAB in the Indian Ocean humpback dolphin (Sousa plumbea) along the Sindhu- durg coast in Maharashtra, India. We describe the subsequent behaviours displayed by the care-giving individuals and other group members. In both cases, an adult ‘postmortem attender’, was observed to sup- port and erratically move around a dead calf. In the second case, the adult–calf pair was escorted by a second adult individual. An examination of the carcass in the first instance revealed blunt force trauma under the right flipper of the calf. These findings suggest that closely associated group members may be dis- tressed by injury to or death of an offspring and stress the importance of long-term behavioural studies. We also discuss the evolutionary significance of PAB in the larger context of social behaviour across mamma- lian groups and the importance of cataloguing these incidents.
... Another line of evidence in support of the intensity of the mother-offspring bond is based on responses to calf death, where the mother (or presumed mother) continues to provide care postmortem. Supportive behavior and postmortem attending have been observed with stillborn or dead calves among many toothed whale speciesincluding bottlenose dolphins (Tursiops spp.) (Tayler and Saayman 1972;Cockcroft and Sauer 1990;Wells 1991;Mann and Barnett 1999;Fertl and Schiro 1994;Connor and Smolker 1989), sperm whales (Physeter macrocephalus) (Reggente et al. 2016), spinner dolphins (Stenella longirostris), beluga whale (Delphinapterus leucas) (Smith and Sleno 1986;Krasnova et al. 2014), killer whales (Orcinus orca), Australian humpback dolphins (Sousa sahulensis), Risso's dolphins (Grampus griseus) (Reggente et al. 2016), Hector's dolphin (Cephalorhynchus hectori) (Stone and Yoshinaga 2000), short-finned pilot whales (Globicephala macrorhynchus) (Reggente et al. 2016), Atlantic spotted dolphin (Alves et al. 2015), rough-toothed dolphins (Steno bredanensis) (Ritter 2007), and tucuxi (Sotalia fluviatilis) (Santos et al. 2000). Almost all cases involve an adult female with a neonate or calf, although similar behaviors are reported between adults. ...
Chapter
Odontocetes are characterized by slow life histories and extensive maternal care, where offspring nurse for years in some species. Among some of the largest toothed whales, the mother and offspring of one or both sexes stay together for a lifetime, forming the basis of strong matrilineal social units and transmission of culture along maternal lines. Mother and calf face a series of challenges from the moment of birth. The newborn must quickly learn to follow and breathe alongside the mother—and wait for her while she dives for food. Within months the calf transitions to infant position for much of the time, although their swimming ability allows them to associate with others in the mother’s network. Because calves can easily become separated from their mothers, an effective communication system is necessary, and signature whistles and pod-specific dialects appear to serve this function. The mother plays a central role in the development of calf social and foraging tactics. Where this has been studied, calves adopt maternal behaviors, including foraging specializations, and share the mother’s network post-weaning. Although difficult to demonstrate “teaching” per se, dolphins are particularly good candidates given their exquisite learning ability and social tolerance. The role of non-mothers is clearly important in calf development, but whether calf interactions with non-mothers constitute “allomothering” remains unclear for most species. What is clear is that group living by cetaceans affords the calf protection from predators and possibly from infanticidal males. The causes of calf mortality are generally not known, as carcasses are rarely retrieved, but disease, predation, poor maternal condition, and anthropogenic causes (pollutants, provisioning, bycatch, boat strikes), and—rarely—infanticide, are all implicated. Weaning occurs when the calf no longer nurses, evident by cessation of infant position swimming. Interbirth intervals are also used as a proxy for weaning, though the calf frequently nurses during the mother’s subsequent pregnancy. Post-weaning, mothers and daughters continue to have preferential bonds, but in killer whales and pilot whales, sons also continue to have a strong relationship with the mother.
... On the one hand, some research on different species of dolphins has indicated consistent and individual differences in relation to different factors such as the behavioural development in wild Bottlenose dolphin new-borns (Mann, 1997;Mann & Smuts, 1999), the different types of bubbles (Marten et al., 1996;McCowan et al., 2000;Pace, 2000), the behavioural responses towards dead conspecifics ( Dudzinski et al., 2003;Fertl & Schiro, 1994), the different captive parenting styles ( Hill et al., 2007;Tizzi & Pace, 2003), the feeding behaviour in two groups of Bottlenose dolphins in the wild ( Gazda et al., 2005), the group movements and the positional leadership in wild Bottlenose dolphins ( Lewis et al., 2005), the dolphins' problem- solving strategies and the exploratory behaviours (Delfour & Marten, 2005;Kuczaj & Yeater, 2006), the social bonds in association with other animals ( Connor et al., 2000;Wells, 1991) and the different types of social behaviours ( Herzing et al., 2003;Kuczaj & Highfill, 2005). ...
... Death-related behaviour is described as a subcategory of epimeletic or nurturant behaviours (i.e. a healthy individual gives attention to an injured or dead one, as summarized in [4]) and is usually seen as a consequence of the cooperative, succouring and protective nature of social mammals [4][5][6][7][8]. Considering that the individual receiving this attention is often an offspring, some authors suggested that this behaviour could be a consequence of the strong mother-offspring bond [9][10][11][12], or a revival attempt through violent manipulation of the bodies [13,14]. In certain cases where the dead or dying individuals were adults, a sexual component and/or a dominance display is involved as observers recorded erections, mounting attempts and other dominance display behaviours [15,16]. ...
Article
Some aquatic mammals appear to care for their dead, whereas others abandon their live offspring when conditions are unfavourable. This incredible variety in behaviours suggests the importance of comparing and contrasting mechanisms driving death-related behaviours among these species. We reviewed 106 cases of aquatic mammals (81 cetaceans and 25 non-cetaceans) reacting to a death event, and extrapolated ‘participant’ (age class, sex, relationship and decomposition) and ‘social’ characteristics (escorting, calf dependence, alloparental care, herding and dispersal patterns) from published and unpublished literature. A multiple correspondence analysis (MCA) was performed to explore the relationships between these characteristics and death-related behaviours, with species clustered based on MCA scores. Results showed that both cetaceans and non-cetaceans react to death but in different ways. Non-cetaceans, characterized by a short maternal investment, were observed to protect the dead (defending it from external attacks), while cetaceans spent much longer with their offspring and display carrying (hauling, spinning, mouthing with the carcass and diving with it) and breathing-related (lifting and sinking the carcass) activities with the dead generally in association with other conspecifics. Our work emphasizes the need of increased documentation of death-related cases around the world to improve our understanding of aquatic mammals and their responses to death. This article is part of the theme issue ‘Evolutionary thanatology: impacts of the dead on the living in humans and other animals’.
Chapter
Dolphins and whales are highly complex, large-brained social mammals. To date, thousands are kept in concrete tanks in marine parks and aquariums around the world. In these environments, they endure lack of control, lack of stimulation, and loss of the ability to engage in activities necessary for them to thrive. The fact that they are such complex, self-aware, intelligent beings makes it more difficult for them to cope in artificial environments, not less, as might be expected. This is because their needs cannot be met outside of their natural habitat. The only ethical response to this situation is to phase out the keeping of dolphins and whales for entertainment and to move those in commercial facilities to sanctuaries that prioritize their needs.
Chapter
Observations of animals engaging in apparently moral behavior have led academics and the public alike to ask whether morality is shared between humans and other animals. Some philosophers explicitly argue that morality is unique to humans, because moral agency requires capacities that are only demonstrated in our species. Other philosophers argue that some animals can participate in morality because they possess these capacities in a rudimentary form. Scientists have also joined the discussion, and their views are just as varied as the philosophers’. Some research programs examine whether animals countenance specific human norms, such as fairness. Other research programs investigate the cognitive and affective capacities thought to be necessary for morality. There are two sets of concerns that can be raised by these debates. They sometimes suffer from there being no agreed upon theory of morality and no clear account of whether there is a demarcation between moral and social behavior; that is, they lack a proper philosophical foundation. They also sometimes suffer from there being disagreement about the psychological capacities evident in animals. Of these two sets of concerns—the nature of the moral and the scope of psychological capacities—we aim to take on only the second. In this chapter we defend the claim that animals have three sets of capacities that, on some views, are taken as necessary and foundational for moral judgment and action. These are capacities of care, capacities of autonomy, and normative capacities. Care, we argue, is widely found among social animals. Autonomy and normativity are more recent topics of empirical investigation, so while there is less evidence of these capacities at this point in our developing scientific knowledge, the current data is strongly suggestive.
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