ERIC WESTERVELT, HOST:

There's a new face - well, fin - in the waters around Seattle. The little black swoosh cutting through the waves is the unmistakable sign of an orca. And the birth of a baby orca whale excited researchers who've documented the mammal's declining population in that corner of the Pacific. But scratch marks on its dorsal fin puzzled longtime whale watcher Ken Balcomb. And when he noticed the youngest whale was swimming with a female who was too old to be the calf's mother, he came to a striking hypothesis - a midwife might have assisted the birth.

Balcomb thinks the baby's companion is actually its grandmother. And after using her teeth help pull the calf out, she's doing something even those of us without fins can understand - giving a new mom some well-deserved rest. Transcript provided by NPR, Copyright NPR.