Footage captured by a mobile phone last August near Kınalıada in Istanbul shows an adult dolphin repeatedly striking a calf, leading to its death, with researchers recently publishing a scientific paper on the phenomenon based on this rare evidence.
The scientists describe this behavior, known as “infanticide,” as a rare occurrence among marine mammals.
Associate professor Mehmet Arda Tonay from Istanbul University’s Faculty of Aquatic Sciences explained: “The video is only 53 seconds long, but it provides an exceptionally rare record and observation globally. We have documented and shared this behavior with the scientific community and the public. This act is believed to be primarily carried out by male dolphins to increase their reproductive success.”
The incident occurred last August off the coast of Kınalıada and was recorded by diver Fibay Korkmaz. Tonay, who is also the vice president of the Turkish Marine Research Foundation (TÜDAV), emphasized the ecological significance of the Marmara Sea, home to dolphin species such as the bottlenose dolphins (Tursiops truncatus), common dolphins (Delphinus delphis) and harbor porpoises (Phocoena phocoena).
Tonay elaborated on the behavior observed in the video: “We see a bottlenose dolphin attacking and killing a calf of its species. Infanticide is a behavior observed in various animals, including fish, amphibians, birds and mammals like primates, lions and bears. However, it is very rarely documented in marine mammals, especially through video recordings.”
The observed behavior is thought to be driven by reproductive strategy. “It is believed that male dolphins kill calves to make the calf’s mother available for mating. Lactating females typically do not mate with other males, so this behavior may increase the male’s reproductive success,” Tonay added.
Tonay noted the importance of this footage, which was initially shared on social media before researchers contacted the diver. “This type of record provides unique insights into the biology, behavior, reproductive strategies and social structures of animals. We encourage citizens to share such footage directly with us, as it is a valuable resource for scientific studies.”
Highlighting the Marmara Sea as a critical habitat for marine mammals, Tonay referred to previous observations of epimeletic behavior (care or protective behavior for a living or deceased individual) recorded in the same area. “Seeing these rarely documented behaviors here is a significant opportunity for us to study and understand them further,” he concluded.