Hunting without an adult could seal an Orca's fate

A killer whale's lunge on to a beach for food can mean death - for the whale. It takes practice, plus the odd nudge from Mum. Malcolm Smith reports

Success in hunting, even if you are a killer whale, doesn't come easy. Perfecting your technique can take years, especially if getting it wrong can seriously endanger your life. What is more, teaching such advanced skills to the point where young killer whales can hunt alone seems to alter substantially the reproductive rate of the adults involved.

The hunting technique in question, arguably one of the most dangerous used by any hunter, involves killer whales intentionally stranding themselves on beaches to grab elephant seal pups. On the beaches on the Crozet Archipelago in British Columbia, Canada, where such seals form a staple food for killer whales, two French biologists - Christopher Guinet and Jerome Bouvier - have been watching the long apprenticeships the young killers must endure.

Adult males - glossy black and white - can be up to 30 feet long and weigh tons. Females are smaller, usually reaching 20 feet. To capture an elephant seal pup lounging around on a beach and take itinto the sea is a remarkable feat for such huge creatures. Avoiding becoming stranded and succumbing to a slow death caused by dehydration and starvation requires considerable strength and agility. The whale must learn to push itself back into a sufficient depth of water to swim away.

What Drs Guinet and Bouvier have reported in the Canadian Journal of Zoology (Vol. 73) is that young killer whales - the calves - didn't even attempt to practise intentional stranding on their own until they were four or five years old. Before that, they were always accompanied by an adult, often the calf's mother. Once they were five or six, they made attempts to catch seal pups, but adults were usually on hand to help.

On some occasions, the adult's presence proved to be essential. Guinet and Bouvier recorded one such remarkable rescue:

"On one occasion, a calf was alone and almost stranded while practising intentional stranding [on a beach]. It experienced difficulties returning to sea. As it was struggling, its mother swam about 50 metres off shore, then turned and accelerated towards the beach. Five metres off the beach, she turned abruptly and produced a large wave that lifted the calf, who then managed to swim back to deep water."

Over a three-year period, the two calves in the pod (whale-watching term for group) were involved in 88 intentional strandings, all except seven taking placewhen no elephant seals were around. The assumption is that these were practice runs. The other seven strandings were done when seal pups were on the beaches, though none of the attempts were successful. Parents, or other adult killer whales, were nearby.

Successes for the whales (but not the seal pups) were recorded during some training runs. In one such event, a whale calf was pushed by its mother so that it grabbed the hapless pup. The female whale then positioned itself between the beach and her calf to prevent it from going too high up the beach. With some pushing by the adult, using her head and upper body, the young killer was able to return to deep water with its prey - truly a case of significant parental support.

It takes a young killer whale around six years, by which stage it is about three-quarters its eventual size, before it can safely catch a seal pup by beaching itself and refloating. Even then, help from a practised adult may be needed.

In other parts of the range of killer whales - throughout much of the Atlantic and Pacific oceans - calves usually don't associate with their mothers once they are about three years old. For instance, in the north Pacific, killer whale calves catch their first salmon within a year and are hunting independently within two years. But catching a large fish at sea is a lot easier for an enormously heavy mammal than grabbing a seal pup virtually on dry land.

The years of parental investment in teaching their apprentices how to catch seal pups - and survive - is the reason, the researchers believe, for the exceptionally low reproductive rate of those killer whales with seals high on their menus.

In waters around British Columbia generally, females, which have a life expectancy of about 50 years, first give birth when they are about 15 years old. Over the next quarter century, they might produce five live calves. At the research site used by Drs Guinet and Bouvier, where the whales seemed dependent upon seal pups, none of the 23 females monitored produced a live calf over a collective period of 47 female years.

No other apprenticeship was surely this costly.

Suggested Topics
Start your day with The Independent, sign up for daily news emails
ebooksA special investigation by Andy McSmith
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Customer Relations Officer

£13000 per annum: Recruitment Genius: This is an exciting opportunity to join ...

Recruitment Genius: IT Help Desk Support

£14500 - £15000 per annum: Recruitment Genius: An IT Help Desk Support individ...

Recruitment Genius: Interim HR Advisor

£27000 - £35000 per annum: Recruitment Genius: We are going through an excitin...

Recruitment Genius: Quantity Surveyor

£37500 - £45000 per annum: Recruitment Genius: Experienced Quantity Surveyor r...

Day In a Page

Homeless Veterans campaign: Donations hit record-breaking £1m target after £300,000 gift from Lloyds Bank

Homeless Veterans campaign

Donations hit record-breaking £1m target after huge gift from Lloyds Bank
Flight MH370 a year on: Lost without a trace – but the search goes on

Lost without a trace

But, a year on, the search continues for Flight MH370
Germany's spymasters left red-faced after thieves break into brand new secret service HQ and steal taps

Germany's spy HQ springs a leak

Thieves break into new €1.5bn complex... to steal taps
International Women's Day 2015: Celebrating the whirlwind wit of Simone de Beauvoir

Whirlwind wit of Simone de Beauvoir

Simone de Beauvoir's seminal feminist polemic, 'The Second Sex', has been published in short-form for International Women's Day
Mark Zuckerberg’s hiring policy might suit him – but it wouldn’t work for me

Mark Zuckerberg’s hiring policy might suit him – but it wouldn’t work for me

Why would I want to employ someone I’d be happy to have as my boss, asks Simon Kelner
Confessions of a planespotter: With three Britons under arrest in the UAE, the perils have never been more apparent

Confessions of a planespotter

With three Britons under arrest in the UAE, the perils have never been more apparent. Sam Masters explains the appeal
Russia's gulag museum 'makes no mention' of Stalin's atrocities

Russia's gulag museum

Ministry of Culture-run site 'makes no mention' of Stalin's atrocities
The big fresh food con: Alarming truth behind the chocolate muffin that won't decay

The big fresh food con

Joanna Blythman reveals the alarming truth behind the chocolate muffin that won't decay
Virginia Ironside was my landlady: What is it like to live with an agony aunt on call 24/7?

Virginia Ironside was my landlady

Tim Willis reveals what it's like to live with an agony aunt on call 24/7
Paris Fashion Week 2015: The wit and wisdom of Manish Arora's exercise in high camp

Paris Fashion Week 2015

The wit and wisdom of Manish Arora's exercise in high camp
8 best workout DVDs

8 best workout DVDs

If your 'New Year new you' regime hasn’t lasted beyond February, why not try working out from home?
Paul Scholes column: I don't believe Jonny Evans was spitting at Papiss Cissé. It was a reflex. But what the Newcastle striker did next was horrible

Paul Scholes column

I don't believe Evans was spitting at Cissé. It was a reflex. But what the Newcastle striker did next was horrible
Miguel Layun interview: From the Azteca to Vicarage Road with a million followers

From the Azteca to Vicarage Road with a million followers

Miguel Layun is a star in Mexico where he was criticised for leaving to join Watford. But he says he sees the bigger picture
Frank Warren column: Amir Khan ready to meet winner of Floyd Mayweather v Manny Pacquiao

Khan ready to meet winner of Mayweather v Pacquiao

The Bolton fighter is unlikely to take on Kell Brook with two superstar opponents on the horizon, says Frank Warren
War with Isis: Iraq's government fights to win back Tikrit from militants - but then what?

Baghdad fights to win back Tikrit from Isis – but then what?

Patrick Cockburn reports from Kirkuk on a conflict which sectarianism has made intractable