After Menopause, Orca Moms Become Group Leaders, Especially When Food Is Scarce

Based on demographic records of Southern Resident orcas since 1976, collected by Ken Balcomb and the Center for Whale Research (San Juan Island, WA), researchers have determined the essential role of post-reproductive females in the orcas’ social structure.

After mother dies in fishing net, calf gets adopted by an unrelated dolphin

Near Mikura Island, Japan, a 15-year-old Indo-Pacific bottlenose dolphin was seen with a recently born calf in April 2012. Sadly, several weeks later the mother got entangled in a recreational fishing net and died. Then, surprisingly, an 8-year-old subadult female adopted the calf even though she had been socially unrelated to the mother: over the course of five years prior to the event, social interactions between them had never been observed.