Bottle Nose Dolphin Adopts Whale Calf of Another Species


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). 

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. “[T]he sea was very calm, and there were many dolphins around,” Carzon, also a PhD student at the Centre 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 took us maybe two minutes to spot them: the dark calf was easy to spot among the bottlenose dolphins.”

DOLPHIN ADOPTION: A female bottlenose dolphin in the South Pacific has been sighted with both her own calf and another young cetacean identified as a melon-headed whale.

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. Carzon grabbed her underwater camera and slipped into the water. “I was able to get good underwater footage and to sex both calves,” she says. ID#TP25’s natural calf was a female; the second calf was male. “I also noticed that both were ‘gently’ pushing each other [in order] to remain under the adult female’s abdomen” in so-called infant position. 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.

Carzon 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. In 1996, researchers observed a newborn spinner dolphin (Stenella longirostrisswimming in the slipstream of an adult male bottlenose—a behavior known as echelon swimming and a common interaction between mothers and calves. 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 new born. Then, in November 1998, a new born 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.

More recently, another adult female bottlenose in the same community has twice been seen with young of a different species. In January 2011, she was spotted with a neonate spinner dolphin for a few days, and in February 2018, she was photographed with a new born Fraser’s dolphin (Lagenodelphis hosei), which swam alongside her in echelon position. With such behaviours apparently relatively common within this social group, ID#TP25 may have picked up a thing or two from her conspecific companions, speculates Carzon. “The evidence that bottlenose dolphins are capable of imitation is very strong,” she says. “[S]ocially transmitted ideas or practices from cultural models may have influenced [ID#TP25’s] behaviour.

The adoption was stable, lasting more than two years.

As is the case with most animal adoptions in the wild, how the mother bottlenose came to acquire the melon-headed whale calf is unknown. 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. Whatever scenario landed the outside calf in the care of dolphin ID#TP25, the adoption was stable, lasting more than two years. ID#TP25’s naturalcalf disappeared by early 2016, suggesting it died or weaned early, possibly joining another social group.

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. 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. “It was amazing because when she appeared, she was tiny tiny tiny,” says Patrícia Izar, a primate ethologist at the University of São Paulo in Brazil who observed the adoption. “She was really a new born, and she survived.” Izar says she was particularly astonished because she knew that some groups of capuchin monkeys eat young marmosets. Care for the young animal was eventually assumed by another female capuchin, and all group members appeared to tolerate the marmoset’s presence.

As for why intraspecies adoptions do—rarely—occur, wildlife conservation professor Robert Young of the University of Salford in the UK suggests that animals may not recognize that they’re caring for young of another species. In the case of the dolphins, the presumed melon-headed whale is similar in size to the adoptive mother’s own bottlenose dolphin calf, and the dolphins have not evolved a strong ability to differentiate their own young from those of another species. “There’s good reason to think it’s just an identification problem,” says Young, who says he has observed a handful of intraspecies adoptions among black-fronted titi monkeys (Callicebus nigrifrons) in Brazil.

The high levels of oxytocin coursing through mammalian mothers’ bodies and the abundance of resources are also likely to be relevant factors. Indeed, in the case of the capuchin group that took in a marmoset baby, Izar and her colleagues had been providing coconuts to study the animals’ use of stones to crack the fruit open, meaning that the monkeys had plenty of food to eat, and so looking after additional young might have been less costly. Interspecies adoptions are also much more common among domestic and captive animals, for whom food is often plentiful, than they are in the wild, Young notes. “If you’ve got a lactating female dog, you can just about get it to rear any other mammal.”

Documented cases of interspecies adoption among the Rangiroa dolphins and Brazilian monkeys “shows that it’s not impossible,” says Izar. “I think that in time we will have other cases in the wild.”



creds to: https://www.the-scientist.com/

Like humans, beluga whales form social networks beyond family ties


Beluga whales

Study first to uncover the role kinship plays in complex groupings and relationships of beluga whales spanning 10 locations across the Arctic

A groundbreaking study using molecular genetic techniques and field studies brings together decades of research into the complex relationships among beluga whales (Delphinapterus leucas) that spans 10 locations across the Arctic from Alaska to Canada and Russia to Norway. The behavior of these highly gregarious whales, which include sophisticated vocal repertoires, suggest that this marine mammal lives in complex societies. Like killer whales (Orcinus orca) and African elephants (Loxodonta Africana), belugas were thought to form social bonds around females that primarily comprise closely related individuals from the same maternal lineage. However, this hypothesis had not been formally tested.

The study, led by Florida Atlantic University’s Harbor Branch Oceanographic Institute, is the first to analyze the relationship between group behaviors, group type, group dynamics, and kinship in beluga whales. Findings, just published in Scientific Reports, reveal several unexpected results. Not only do beluga whales regularly interact with close kin, including close maternal kin, they also frequently associate with more distantly related and unrelated individuals.

Findings indicate that evolutionary explanations for group living and cooperation in beluga whales must expand beyond strict inclusive fitness arguments to include other evolutionary mechanisms. Belugas likely form multi-scale societies from mother-calf dyads to entire communities. From these perspectives, beluga communities have similarities to human societies where social networks, support structures, cooperation and cultures involve interactions between kin and non-kin. Given their long lifespan (approximately 70 years) and tendency to remain within their natal community, these findings reveal that beluga whales may form long-term affiliations with unrelated as well as related individuals.

“This research will improve our understanding of why some species are social, how individuals learn from group members and how animal cultures emerge,” said Greg O’Corry-Crowe, Ph.D., lead author and a research professor at FAU’s Harbor Branch. “It also has implications for traditional explanations based on matrilineal care for a very rare life-history trait in nature, menopause, which has only been documented in a handful of mammals, including beluga whales and humans.”

Researchers found that belugas formed a limited number of group types, from mother-calf dyads to adult male groups, and from mixed-age groups to large herds. These same group types were consistently observed across population and habitats. Furthermore, certain behaviors were associated with group type, and group membership was found to often be dynamic.

“Unlike killer and pilot whales, and like some human societies, beluga whales don’t solely or even primarily interact and associate with close kin. Across a wide variety of habitats and among both migratory and resident populations, they form communities of individuals of all ages and both sexes that regularly number in the hundreds and possibly the thousands,” said O’Corry-Crowe. “It may be that their highly developed vocal communication enables them to remain in regular acoustic contact with close relatives even when not associating together.”

Beluga whale groupings (beyond mother-calf dyads) were not usually organized around close maternal relatives. The smaller social groups, as well as the larger herds, routinely comprised multiple matrilines. Even where group members shared the same mtDNA lineage, microsatellite analysis often revealed that they were not closely related, and many genealogical links among group members involved paternal rather than maternal relatives. These results differ from earlier predictions that belugas have a matrilineal social system of closely associating female relatives. They also differ from the association behavior of the larger toothed whales that informed those predictions. In ‘resident’ killer whales, for example, both males and females form groups with close maternal kin where they remain for their entire lives.

“Beluga whales exhibit a wide range of grouping patterns from small groups of two to 10 individuals to large herds of 2,000 or more, from apparently single sex and age-class pods to mixed-age and sex groupings, and from brief associations to multi-year affiliations,” said O’Corry-Crowe. “This variation suggests a fission-fusion society where group composition and size are context-specific, but it may also reflect a more rigid multi-level society comprised of stable social units that regularly coalesce and separate. The role kinship plays in these groupings has been largely unknown.”

For the study, researchers used field observations, mtDNA profiling, and multi-locus genotyping of beluga whales to address fundamental questions about beluga group structure, and patterns of kinship and behavior, which provide new insights into the evolution and ecology of social structure in this Arctic whale.

The study was conducted at 10 locations, in different habitats, across the species’ range, spanning from small, resident groups (Yakutat Bay) and populations (Cook Inlet) in subarctic Alaska to larger, migratory populations in the Alaskan (Kasegaluk Lagoon, Kotzebue Sound, Norton Sound), Canadian (Cunningham Inlet, Mackenzie Delta, Husky Lakes) and Russian (Gulf of Anadyr) Arctic to a small, insular population in the Norwegian High Arctic (Svalbard).

“This new understanding of why individuals may form social groups, even with non-relatives, will hopefully promote new research on what constitutes species resilience and how species like the beluga whale can respond to emerging threats including climate change,” said O’Corry-Crowe.



Source: https://www.sciencedaily.com/