BBC Wildlife - UK (2021-12)

discoverwildlife.com BBC WILDLIFE 27

FEMALE

OF THE SPECIES

I

most marine animals. Not even

the great white’s only known

assailant, enjoy slashing them

like hors d’oeuvres.

different. Yet we have a very unusual

of only five are known to live well beyond

their reproductive capacity: four species of

toothed whale and us. Why?

Monitoring hormones in a giant

swimming torpedo with teeth isn’t easy

– which is how I came to be cruising the

Pacific Northwest in a tiny boat trying to

catch orca faeces in a net. Fishing for scat

is the least invasive (not to mention safest)

means of monitoring hormones and health

in a killer whale.

I was assisting Deborah Giles, a

researcher at the University of Washington

who studies the southern residents, a pod of

about 70 orcas that have been monitored for

almost 50 years. Originally, it was assumed

they were led by the biggest male, and the

smaller females made up his harem. We now

understand that these highly social cetaceans

live in extended family groups. Their

leaders are not only female, but are

the post-menopausal grannies.

These wise old matriarchs

are living libraries for the

environmental and cultural

knowledge that keeps their

clan alive. Orcas in captivity

have been shown to have

phenomenal photographic

memories, remembering testing patterns

after 25 years. Orca brains are the heaviest

on the planet, with a proportionally bigger

cerebrum than humans. Female orcas have a

higher brain-to-body ratio than males, giving

them even more computational power – and

helping matriarchs recall fishing spots.

When Giles and I finally located an orca

matriarch she was hunting with her son.

This close family relationship is the key to

their menopausal riddle. Orcas are unique

amongst social mammals in that neither sons

nor daughters permanently leave their birth

group. This means that orca females end up

competing across the generations for the

extra resources needed during pregnancy

and lactation.

So orca matriarchs stop breeding at

about 40 years old and invest in their

sons instead, whose offspring will

be born outside of the family group

to unrelated females and therefore

less of a drain on pod resources.

Whether this familial conflict

existed amongst early humans

remains a mystery. But orca

males are known for being

massive ‘mummies’ boys’,

kept alive by their post-

menopausal matriarch’s

hunting handouts.

Lucy Cooke is a zoologist,

broadcaster and author of

The Unexpected Truth

About Animals

Lucy Cooke on menopausal

matriarchs and mummies’ boys

NEWS ROUND UP

Big Butterfly Count

2021 results

Butterfly Conservation’s annual

survey, which ran from 16th July to

8th August, has reported the lowest

number of butterflies recorded since

it began 12 years ago. It has revealed

a continued decline of butterflies and

moths across the UK, including the

much-loved small tortoiseshell and

peacock butterflies.

Infectious disease

confirmed in

wild chimps

Leprosy has been found in wild

chimpanzees for the first time,

according to a study in the journal

Nature Reviews Microbiology. Cases

of the disease have been confirmed

in two unconnected populations in

Guinea-Bissau and the Ivory Coast.

The origins of the infections are

unclear but humans are considered

the main host for the bacteria that

causes the illness.

Bird eggshells

evolve to suit

environment

Research conducted at Royal

Holloway, University of London,

suggests the moisture resistance of

eggshells has evolved to thrive in the

habitats favoured by the birds that lay

them. However, the findings indicate

that birds in areas susceptible to rapid

climate-change effects may be more

at risk than previously thought.

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Older female orcas dote on their sons