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Resembling in many ways their human counterparts, female
killer whales breed between ages 14 and 40 but can survive well
into their 90s, while male orcas, by contrast, die much younger,
rarely making it past 50, according to the study in the journal
Current Biology.
Killer whales join short-finned pilot whales and humans as the
only species in which the females can live decades after
menopause. In that time, the female killer whales, not burdened
by childbearing, pass on important information to the other
whales, says the study.
"The value gained from the wisdom of elders can help explain why
female resident killer whales and humans continue to live long
after they have stopped reproducing," the study said.
To study the orcas' behavior, marine mammal researchers from
York and Exeter universities in Britain and the Center for Whale
Research in Washington state analyzed 751 hours of video of
killer whales taken over nine years on their annual Pacific
Ocean salmon migrations off British Columbia and Washington
state.
The older female whales "were more likely to lead group movement
compared to reproductively aged females," the study said.
Specifically, they are the leaders as the whales forage in
groups for Chinook salmon, their primary food source.
And when things are tough, the older females step up even more,
the study says.
"Leadership by post reproductive-aged females is especially
prominent in difficult years when salmon abundance is low," the
report says. "This finding is critical because salmon abundance
drives both mortality and reproductive success."
(Editing by Cynthia Johnston and Sandra Maler)
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