Male-male aggression renders bottlenose dolphin (&lt;I&gt;Tursiops truncatus&lt;/I&gt;) unconscious

Parsons, Kim M.; Durban, John W.; Claridge, Diane

doi:10.1578/01675420360736532

Cited by 29 publications

(16 citation statements)

References 11 publications

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“…High tooth rake prevalence among juvenile females may be the result of frequent interactions with juvenile male dolphins (Krzyszczyk et al 2017). Additionally, it is important to note that tooth rakes are superficial wounds and do not represent serious aggressive behaviors such as ramming, body slams, and tail hits, which might be more lethal (e.g., Parsons et al 2003;Lusseau 2006).…”

Section: Discussionmentioning

confidence: 99%

Every scar has a story: age and sex-specific conflict rates in wild bottlenose dolphins

Lee

Wallen

Krzyszczyk

et al. 2019

Behav Ecol Sociobiol

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Social living brings competition over mates, relationships, and resources, which can translate to direct conflict. In dolphins, tooth rakes received from conspecifics are highly visible and reliable indicators of conflict. New rakes indicate recent conflicts while healed rakes suggest older instances of conflict. Here, we investigate the healing time of conspecific tooth rakes in wild bottlenose dolphins, create a demographic profile of injury risk in the population, and consider the implications for age-and sex-specific aggression. Using photographic and scarring data from the Shark Bay Dolphin Research Project spanning 31 years (N = 269 tooth rakes), healing time was analyzed using a subset of sequential photographs of the same body part over 1-12 years (N = 70 tooth rakes). Ninety percent of tooth rakes in males and 95% of tooth rakes in females were no longer visible within 400 days, with males taking longer to heal than females. Using the full sample, we examined age and sex-effects on the prevalence of new tooth rakes. A negative quadratic model best fitted tooth rake prevalence patterns from ages 0 to 13 and a positive linear regression best fitted tooth rake prevalence patterns from ages 13 to 30. Both analyses revealed significant age and sex effects, where males had more tooth rakes than females. Age differences in tooth rake prevalence may be attributed to life history events such as sexual maturity onset, male-male competition and alliance formation, and sexual coercion. These results contribute to our understanding of the relationship between social conflict and life history strategies in long-lived mammals. Significance statement In wild dolphins, tooth rake scars indicate conspecific conflict, and the timing of such conflict clarifies the challenges faced during each life history stage. Based on > 30 years of longitudinal data, we created a demographic profile of new tooth rakes to identify patterns of age-and sex-specific received aggression. Males had more tooth rakes than females, but females healed faster than males. Juveniles had the greatest tooth rake prevalence compared to calves and adults, suggesting greater exposure to some level of conflict. Differences in patterns of tooth rake prevalence and aggression have implications regarding the costs of sexual maturity and reproduction in dolphins. To our knowledge, no study has examined the rate of received aggression across the lifespan. Our methods can be applied to other studies of wild marine mammals, where agonistic encounters are difficult to observe, but wounds are apparent.

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Section: Discussionmentioning

confidence: 99%

Every scar has a story: age and sex-specific conflict rates in wild bottlenose dolphins

Lee

Wallen

Krzyszczyk

et al. 2019

Behav Ecol Sociobiol

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“…A comparison of average scarring levels between the east coast (n = 76; dark grey), Hebrides (n = 23; light grey), and Sound of Barra (n = 12; white) bottlenose dolphins scars (Slooten, 1994;MacLeod, 1998;Parsons et al, 2003a;Silva-Jr et al, 2005). Furthermore, there have also been instances when play behaviour turns aggressive (Scott et al, 2005).…”

Section: Figurementioning

confidence: 99%

“…Studies of aggression in wild bottlenose dolphins have generally used information from stranded animals (Patterson et al, 1998), from one or more direct observations (Parsons et al, 2003a;Cotter et al, 2011), or from interspecific interactions (Ross & Wilson, 1996;Herzing et al, 2003). Scars and natural markings have been used for individual identification of cetaceans (Würsig & Jefferson, 1990).…”

Section: Introductionmentioning

confidence: 99%

Using Tooth Rakes to Monitor Population and Sex Differences in Aggressive Behaviour in Bottlenose Dolphins (Tursiops truncatus)

Marley

Cheney

Thompson³

2013

Aquat Mamm

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This study investigated intraspecific tooth rake scarring, an established indicator of received aggression by conspecifics, on bottlenose dolphins (Tursiops truncatus) to gain knowledge of aggressive interactions. The differences in tooth rake scarring between male and female dolphins on the east coast of Scotland were examined, and overall levels of scarring were compared with dolphins on the west coast of Scotland (Sound of Barra and Hebrides). Photographs were examined for evidence of tooth rake scarring using four different methods. East coast males displayed significantly higher scarring percentages (i.e., body area covered by tooth rake scarring), numbers of dorsal fin rake directions (i.e., whether tooth rake scars were vertical, horizontal, diagonal, or curved), and nick percentage (i.e., amount of the dorsal fin missing due to nicks) than females. Differences also existed between the three areas, with bottlenose dolphins around the Sound of Barra showing significantly lower levels of dorsal fin rake directions than those on the east coast or Hebrides. Observed sex differences are likely the result of intrasexual conflict between males over access to females. However, other factors such as sex-or age-specific behaviours or sexual coercion of females may also be involved. Such information could potentially be used to differentiate between the sexes. The differences in dorsal fin scarring between these populations suggests differences in aggressive interactions, possibly indicating differences in social structure. The lower scarring levels seen in the Sound of Barra group may support the suggestion that bottlenose dolphins on the west coast belong to two communities. However, this variability in conspecific aggression may also be the result of different social behaviours, age or sex ratios, habitat, resources, or individual behavioural differences.

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“…Aggressive encounters involving individuals of the same species are largely described in the literature [e.g., (9,10)], including the formation of male alliances (11)(12)(13). Male alliances are responsible for violent kidnappings ("herding events") of non-pregnant females to increase their mating opportunities as well as of infanticides in different cetacean species such as the Amazon river dolphin (Inia geoffrensis) (14), Indo-Pacific humpback dolphin (Sousa chinensis) (15), killer whale (16), tucuxi dolphin (Sotalia guianensis) (17), and bottlenose dolphin (Tursiops spp.)…”

Section: Introductionmentioning

confidence: 99%

Retrospective Study of Traumatic Intra-Interspecific Interactions in Stranded Cetaceans, Canary Islands

et al. 2020

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Aggressive encounters involving cetacean species are widely described in the literature. However, detailed pathological studies regarding lesions produced by these encounters are scarce. From January 2000 to December 2017, 540 cetaceans stranded and were necropsied in the Canary Islands, Spain. Of them, 24 cases of eight species presented social traumatic lesions produced by cetaceans of the same or different species. All the cases presented severe multifocal vascular changes, 50% (12/24) presented fractures affecting mainly the thoracic region, 41.7% (10/24) acute tooth-rake marks, 37.5% (9/24) undigested food in the stomach, 33.3% (8/24) tracheal edema, and 12.5% (3/24) pulmonary perforation. In 10 cases with tooth-rake marks, the distance between the teeth, allowed us to further identify the aggressor species: four cases were compatible with killer whales (Orcinus orca) affecting three species [pigmy sperm whale (Kogia breviceps), Cuvier's beaked whale (Ziphius cavirostris), and short-finned pilot whale (Globicephala macrorhynchus)] and four cases compatible with common bottlenose dolphins (Tursiops truncatus) affecting two species [short-beaked common dolphin (Delphinus delphis) and Atlantic spotted dolphin (Stenella frontalis)]. We also described two cases of intraspecific interaction in stripped dolphin (Stenella coeruleoalba). Microscopically, 70.8% (17/24) of the cases presented acute degenerative myonecrosis, 66.7% (14/21) presented vacuoles in the myocardiocytes, 36.8% (7/19) pigmentary tubulonephrosis, 31.6% (6/19) cytoplasmic eosinophilic globules within hepatocytes, 21.4% (3/14) hemorrhages in the adrenal gland, and 17.3% (4/23) bronchiolar sphincter contraction. The statistical analysis revealed that deep divers, in good body condition and nearby La Gomera and Tenerife were more prone to these fatal interactions. Additionally, in this period, three animals died due to an accident during predation: a false killer whale (Pseudorca crassidens) died because of a fatal attempt of predation on a stingray, and two Risso's dolphins (Grampus griseus) died as a consequence of struggling while predating on large squids.

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Male-male aggression renders bottlenose dolphin (<I>Tursiops truncatus</I>) unconscious

Cited by 29 publications

References 11 publications

Every scar has a story: age and sex-specific conflict rates in wild bottlenose dolphins

Every scar has a story: age and sex-specific conflict rates in wild bottlenose dolphins

Using Tooth Rakes to Monitor Population and Sex Differences in Aggressive Behaviour in Bottlenose Dolphins (Tursiops truncatus)

Retrospective Study of Traumatic Intra-Interspecific Interactions in Stranded Cetaceans, Canary Islands

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