Infanticide in a mammal-eating killer whale population

Towers, Jared R.; Hallé, Muriel J.; Symonds, Helena; Sutton, Gary J.; Morton, Alexandra; Spong, Paul; Borrowman, James P.; Ford, John K. B.

doi:10.1038/s41598-018-22714-x

Cited by 28 publications

(25 citation statements)

References 49 publications

(43 reference statements)

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“…Intra- and interspecific interactions among cetaceans are diverse and complex, and often aggressive in nature [ 143 , 144 , 145 , 146 , 147 ]. Several reports describe severe injuries in calves, including infanticide [ 145 , 146 , 148 , 149 , 150 ]. Predation of other cetaceans is well known for the killer whale ( Orcinus orca ), which has been observed attacking or harassing over 20 different species of cetaceans, including families Balaenopteridae, Balaenidae, Eschrichtiidae, Physeteridae, Ziphiidae, Monodontidae, Delphinidae and Phocoenidae [ 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 ].…”

Section: Discussionmentioning

confidence: 99%

Pathologic findings and causes of death of stranded cetaceans in the Canary Islands (2006-2012)

et al. 2018

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This study describes the pathologic findings and most probable causes of death (CD) of 224 cetaceans stranded along the coastline of the Canary Islands (Spain) over a 7-year period, 2006–2012. Most probable CD, grouped as pathologic categories (PCs), was identified in 208/224 (92.8%) examined animals. Within natural PCs, those associated with good nutritional status represented 70/208 (33.6%), whereas, those associated with significant loss of nutritional status represented 49/208 (23.5%). Fatal intra- and interspecific traumatic interactions were 37/208 (17.8%). Vessel collisions included 24/208 (11.5%). Neonatal/perinatal pathology involved 13/208 (6.2%). Fatal interaction with fishing activities comprised 10/208 (4.8%). Within anthropogenic PCs, foreign body-associated pathology represented 5/208 (2.4%). A CD could not be determined in 16/208 (7.7%) cases. Natural PCs were dominated by infectious and parasitic disease processes. Herein, our results suggest that between 2006 and 2012, in the Canary Islands, direct human activity appeared responsible for 19% of cetaceans deaths, while natural pathologies accounted for 81%. These results, integrating novel findings and published reports, aid in delineating baseline knowledge on cetacean pathology and may be of value to rehabilitators, caregivers, diagnosticians and future conservation policies.

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Section: Discussionmentioning

confidence: 99%

Pathologic findings and causes of death of stranded cetaceans in the Canary Islands (2006-2012)

et al. 2018

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“…While it remains unclear if post-reproductive lifespans have evolved among Bigg's killer whales [136], there is a documented case of infanticide among this ecotype [137], where a post-reproductive female and her mature male offspring cooperatively killed the calf of an unrelated female in the same population. This may represent an extreme case of late-life helping, driven by inclusive fitness and likely sexual selection [137], illustrating how highly modular social structure organized around female kinship structure can draw boundaries across which rather direct competition can be selected for. In killer whales then, we have the opportunity to explore the consequences of some of the most extreme forms of female-based kinship structure in mammals.…”

Section: Maternal Kinship In Toothed Whalesmentioning

confidence: 99%

Causes and consequences of female centrality in cetacean societies

Rendell

Cantor

Gero

et al. 2019

Phil. Trans. R. Soc. B

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Cetaceans are fully aquatic predatory mammals that have successfully colonized virtually all marine habitats. Their adaptation to these habitats, so radically different from those of their terrestrial ancestors, can give us comparative insights into the evolution of female roles and kinship in mammalian societies. We provide a review of the diversity of such roles across the Cetacea, which are unified by some key and apparently invariable life-history features. Mothers are uniparous, while paternal care is completely absent as far as we currently know. Maternal input is extensive, lasting months to many years. Hence, female reproductive rates are low, every cetacean calf is a significant investment, and offspring care is central to female fitness. Here strategies diverge, especially between toothed and baleen whales, in terms of mother–calf association and related social structures, which range from ephemeral grouping patterns to stable, multi-level, societies in which social groups are strongly organized around female kinship. Some species exhibit social and/or spatial philopatry in both sexes, a rare phenomenon in vertebrates. Communal care can be vital, especially among deep-diving species, and can be supported by female kinship. Female-based sociality, in its diverse forms, is therefore a prevailing feature of cetacean societies. Beyond the key role in offspring survival, it provides the substrate for significant vertical and horizontal cultural transmission, as well as the only definitive non-human examples of menopause. This article is part of the theme issue ‘The evolution of female-biased kinship in humans and other mammals’.

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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.) (1,2,18,19).…”

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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Infanticide in a mammal-eating killer whale population

Cited by 28 publications

References 49 publications

Pathologic findings and causes of death of stranded cetaceans in the Canary Islands (2006-2012)

Pathologic findings and causes of death of stranded cetaceans in the Canary Islands (2006-2012)

Causes and consequences of female centrality in cetacean societies

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

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