Wild dolphin 'super mom' adopts orphaned whale calf
One bottlenose dolphin mom has surprised a group of researchers with her unusual parenting skills.
The young female is believed to be the first dolphin on record -- and only the second mammal ever observed -- to have adopted not only outside her species but outside her genus, having taken on raising not only her own offspring but a melon-headed whale calf as well.
Image courtesy Pamela Carzon
A study recently published in the journal Ethology documents how researchers tracked the unlikely family beginning in 2014 near Rangiroa Atoll, part of French Polynesia. While the dolphin was initially observed with one calf of her own -- after a 12-month gestation period -- a second baby joined their ranks only a month later.
It was not only the sudden appearance but also the physical appearance of this second baby that caught the researchers' attention. "The second calf ... possessed a slender profile, rounded head and blunt rostrum, pointed pectoral fins," said the team. "All morphological characteristics of a melon‐headed whale."
The melon-headed whale calf, taking after his adopted mother. Image courtesy Pamela Carzon
"To my knowledge, this phenomenon is the first of its kind observed in wild mammals that have only one calf at a time," says the study's lead author, Pamela Carzon, a scientist with the Marine Mammal Study Group in Polynesia.
Carzon does point out that bottlenose dolphins sometimes 'kidnap' other animals' offspring, but she and the team doubt that is the case with this unusual pair. For one, those dolphins who do 'borrow' young from others tend not to have their own, and the borrowed babies tend to disappear quickly. In the case of this dolphin mom, her biological offspring, and the adopted whale calf, the group was seen together for at least a year. And when they were separated, it was the biological calf who disappeared first (believed to have either moved onto a new social group or met with an untimely death).
Image courtesy Pamela Carzon
All of this leads to the question -- how did this unlikely family come to be? While it's impossible to know what exactly led to the arrangement, particularly as researchers don't know what happened to the whale's actual mother, signs are the animals' personalities played a key role.
The mother dolphin in question was noted to be "curious and social," repeatedly interacting with scuba-divers. The whale calf stood out for his "persistence in initiating and maintaining the interaction," as he was often seen pushing his adoptive sister out of the way and engaging with the mother.
"Whereas the young melon-headed whale was certainly the main initiator of this adoption," says Carzon, "the mother's remarkably permissive personality could have played a crucial role in the process."
The melon-headed whale calf has also picked up behaviours from his adoptive community, surfing, jumping, and socializing with other bottlenose dolphins.
"If he comes to the age of weaning," says Carzon, "it's very likely that he'll live a bottlenose dolphin life."
Sources: Ethology/Wiley | ScienceAlert | Smithsonian |
