ainawgsd:

Adoption is uncommon among wild mammals, with most occurring between related members of the same species. The only other scientifically documented case involving an adopted orphan of a different species and genus was in 2006, when University of São Paulo primatologist Patrícia Izar observed a group of capuchins caring for a baby marmoset. “At the time, we were really, really astonished,” she says.

Female bottlenose dolphins have been known to “steal” babies of other species for brief periods during conflicts, but the adoptee’s enthusiasm and the mom’s dedication show this was no kidnapping.

The ever-persistent orphan was not only intent on integrating himself into the family unit; he also figured out how to fit into the broader group of dolphins. For instance, he regularly socialized with other youngsters and would even join in on their favorite pastime of surfing and leaping into the waves.

But a big question remains: Why would a bottlenose dolphin bother to invest in an infant to which she has no genetic ties?

One possibility is that the recent birth of her calf triggered her maternal instincts. “Most likely, it was just a perfect moment for this calf to come along, when [the mother] was at a very receptive period to forming those bonds with her own offspring,” says MacLeod, “and it led to this slightly wacky situation.”