08 June 2011

Not all penguin parents are created equal

AUSTRALIA - It's a common complaint among human parents that one of them isn't pulling their weight when it comes to raising the kids. Well, it appears that little penguins have the same issue.

A new paper published in the International Society for Behavioural Ecology's journal shows some individual penguins work harder than their partners to feed their chicks.

The study is part of joint research between Australian and French scientists. According to one of the paper’s authors, Phillip Island Nature Parks penguin biologist Dr Andre Chiaradia, the findings come as something of a surprise - it was previously thought both parents contributed equally to raising chicks.

“In fact, over-achieving individuals pairing with under-achievers appears to be the norm (75% of the cases) rather than the previously expected cool new-age ‘let’s do it equally’ thinking.”

Dr Chiaradia said the inequality in parenting effort is most likely because one parent is actually better at foraging for food, largely because they are fitter and so put more effort into it.

“Penguins are a bit like elite athletes. They put huge effort into being the best. But only the very few overachievers will get the medals. Basically they optimize their decisions in order to maximise their fitness.

"Interestingly with little penguins, gender and age seems to make no difference. The penguin can be older or younger, male or female. If it is an over-achiever, it will do more work,” Dr Chiaradia said.

On the face of it, the research findings might appear to be of little more than novelty value, but Dr Chiaradia said that, in fact, finding such individual qualities in animals is crucial, as it contributes to understanding the reproduction and survival resilience of animals to changes in their environment.

“What the research found was that if the penguin pair included one over-achiever, then the pairs’ reproduction and their offspring survival rate is improved, compared to if the pair were equal in their parenting effort.

“A penguin’s parenting effort really becomes important during the period when the chicks cannot feed themselves, and when the parents must deliver the meals.

“The importance of ‘effort’ is particularly evident in non-favourable years - in years where food is hard to find, or other unusual elements occur in the penguin’s habitat and environment,” Dr Chiaradia said.

He said humans have many ‘comfort’ factors to help manage parenting and their offspring’s survival.

“We humans have ‘security nets’ in life, such as extended families, child care, schools, welfare and easy access to food. However penguins have only each other to rely on. So if one is able to do more in raising the offspring, then all have more of a chance of survival.”

Everybody, needs somebody ... unequal parenting in little penguins, 6 June 2011, Phillip Island Nature Parks

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