A female monkey that the researchers had thought was pregnant but who perhaps lost her own baby cared for the infant marmoset, carrying it on her back and appearing to nurse it. There is only one other published case of intraspecies adoption by animals in the wild: for about 14 months in the early 2000s, researchers documented the integration of an infant marmoset ( Callithrix jacchus) into a group of capuchin monkeys ( Cebus libidinosus) in woodland savanna of central Brazil. ID#TP25’s naturalcalf disappeared by early 2016, suggesting it died or weaned early, possibly joining another social group. Whatever scenario landed the outside calf in the care of dolphin ID#TP25, the adoption was stable, lasting more than two years. The calf’s natural mother may have died, or the bottlenose dolphin group may have “kidnapped” it, a behavior that was once observed in a dolphin group in the Bay of Gibraltar, Carzon notes. The adoption was stable, lasting more than two years.Īs is the case with most animal adoptions in the wild, how the mother bottlenose came to acquire the melon-headed whale calf is unknown. “ocially transmitted ideas or practices from cultural models may have influenced behavior.” “The evidence that bottlenose dolphins are capable of imitation is very strong,” she says. With such behaviors apparently relatively common within this social group, ID#TP25 may have picked up a thing or two from her conspecific companions, speculates Carzon. In January 2011, she was spotted with a neonate spinner dolphin for a few days, and in February 2018, she was photographed with a newborn Fraser’s dolphin ( Lagenodelphis hosei), which swam alongside her in echelon position. More recently, another adult female bottlenose in the same community has twice been seen with young of a different species. Then, in November 1998, a newborn melon-headed whale spent a few weeks in the area and was filmed swimming in echelon position with the same female bottlenose that had associated with the young spinner dolphin. Scientists also regularly spotted a juvenile spinner dolphin over the next two years, often with a particular adult female bottlenose, Carzon says, although it’s not clear whether it was the same individual they saw as a newborn. In 1996, researchers observed a newborn spinner dolphin ( Stenella longirostris) swimming in the slipstream of an adult male bottlenose-a behavior known as echelon swimming and a common interaction between mothers and calves. Ĭarzon had been studying the bottle-nose dolphin community inhabiting the northern part of Rangiroa atoll for a decade and knew that the cetaceans had a history of bringing young animals of other species into their group. Continued observation over the following months revealed that the dolphin mom was nursing the foreign calf, whose species ID remains to be confirmed with genetic testing, and otherwise treated him as one of her own. “I also noticed that both were ‘gently’ pushing each other to remain under the adult female’s abdomen” in so-called infant position. ID#TP25’s natural calf was a female the second calf was male. “I was able to get good underwater footage and to sex both calves,” she says. Carzon grabbed her underwater camera and slipped into the water. The mother, dubbed ID#TP25 by the researchers, was known to tolerate divers and boats, and that April day she approached the inflatable with both calves. Pamela Carzon, Marine Mammal Study Group of French Polynesia “It took us maybe two minutes to spot them: the dark calf was easy to spot among the bottlenose dolphins.” “he sea was very calm, and there were many dolphins around,” Carzon, also a PhD student at the Center for Island Research and Environmental Observatory (CRIOBE) in French Polynesia and the École Pratique des Hautes Études in Paris, recalls in an email to The Scientist. It was April 2015, and Carzon and a colleague at the Marine Mammal Study Group of French Polynesia, a nongovernmental organization dedicated to whale and dolphin conservation, were out for the NGO’s annual photo-ID survey, very much hoping to find animals that a former collaborator had seen while diving in the region the previous November. From a small inflatable boat in the Rangiroa atoll in French Polynesia, Pamela Carzon got her first glimpse of the “strange” trio of marine mammals she’d been told about: a bottlenose dolphin mother ( Tursiops truncatus), her seven-month-old calf, and another young cetacean that was slightly smaller and looked to be not a bottlenose dolphin at all, but a melon-headed whale ( Peponocephala electra).
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