After they reach menopause, female killer whales help their kin to survive by sharing their hunting expertise.

Credit: Alex Huizinga, NIS/Minden Pictures/FLPA

Humans, killer whales (Orcinus orca; pictured) and one other whale species are the only animals whose females are known to experience a long post-reproductive life. Female orcas can live into their 90s, even though they stop reproducing in their 40s. Darren Croft at the University of Exeter, UK, and his team analysed more than 750 hours of video footage of killer whales off the US Pacific coast collected between 2001 and 2009. Observations of 102 different whales up to 91 years old showed that post-reproductive females tended to lead group hunts for salmon, an important source of food. This leadership was particularly pronounced in years when salmon were scarce.

This is the first direct evidence that post-menopausal females are a source of ecological know-how, the authors say.

Curr. Biol. (2015)