Journal of Ethology

, Volume 34, Issue 3, pp 299–307

Infanticide in the Indo-Pacific humpback dolphin (Sousa chinensis)

Article

DOI: 10.1007/s10164-016-0475-7

Cite this article as:
Zheng, R., Karczmarski, L., Lin, W. et al. J Ethol (2016) 34: 299. doi:10.1007/s10164-016-0475-7

Abstract

Infanticide has been observed in several mammalian taxa and studied in considerable detail in carnivores and primates. Although reported previously in cetaceans, known cases are few and their socio-behavioral context remains poorly understood. We report here on three cases of social coercion directed at mother-neonate pairs of Indo-Pacific humpback dolphins (Sousa chinensis) in the Pearl River Estuary, southeast China. Two of these cases resulted in confirmed infanticide. To aid the interpretation of our field observations, we refer to the results of necropsies of calf carcasses stranded and recovered in our research area between 2003 and 2012, which indicate that in several cases the main cause of death of stranded calves was asphyxia resulting from blunt-force trauma. This is consistent with the aggressive behaviors seen during our field observations. We conclude that male infanticide is the most plausible interpretation of the observed behaviors, never previously reported for the genus Sousa, while the calf-directed aggression is likely a result of socio-sexual harassment by males as part of their reproductive strategy.

Keywords

Sexual coercion Sexual selection Sexual conflict Pearl River Estuary Cetaceans—dolphins 

Supplementary material

10164_2016_475_MOESM1_ESM.jpg (3.9 mb)
Supplementary material S1. Photo-ID images indicating the age of all individuals involved in the three cases of calf-directed aggression in Indo-Pacific humpback dolphins seen in the Pearl River Estuary in 2011 and 2012. In this species, the pattern of pigmentation changes with age, from dark gray at birth to light gray as juveniles and mottled or light pink as adults (for details see Jefferson 2000, Jefferson et al. 2012). White ID numbers on black background indicate the presumed mothers and black ID numbers on white background depict the perpetrators. One of the perpetrators was a large sub-adult and all other individuals were adults (JPEG 3993 kb)

Copyright information

© Japan Ethological Society and Springer Japan 2016

Authors and Affiliations

  1. 1.South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, School of Marine SciencesSun Yat-Sen UniversityGuangzhouPeople’s Republic of China
  2. 2.The Swire Institute of Marine Science, School of Biological SciencesThe University of Hong KongShek OHong Kong