10 March 2011

When the going gets tough, the tough keep breeding

It looks determined, but is this Adelie
penguin at Palmer Station a super-
breeder? Photo by Johnny Shaw.
Some rights reserved.
ANTARCTICA - Is it a bird? Is it a plane? No, it's a super-breeder! Actually, the answer to the first question is yes, it is a bird - an Adelie penguin, in fact. But what makes a penguin a super-breeder? Grant Ballard, David Ainley and Katie Dugger are co-principal investigators in a study looking at what makes some individual penguins better at foraging and breeding than others. What they find out will help them predict how penguins as a species will cope with climate change.

Ainley told the Antarctic Sun that while more penguins breed in "easy" years, during the "tough" years - when the sea ice extends and the journey to the open sea for food causes many penguin parents to fail - there are "super-breeders" that manage to raise their chicks to adulthood. These super-breeders, which sustain the population consistently, make up about 20% of a given colony.

The scientists have a large pool of banded, known-age birds they can track. They randomly select some super-breeders and normal penguins from the pool to wear time-depth recorders and monitor how long and deep each penguin dives on its foraging trips.

"We found these super-breeders are much better foragers. They dive deeper; they have a shorter recovery period at the surface between dives. They bring back more food," said Ainley.

Because the super-breeders forage more efficiently, it means their chicks get more food more often, as well as more parental protection for predators like skuas.

Ballard said that it is probably a combination of age and experience as well as genetics - being faster and stronger - that makes a penguin a super-breeder. Being older doesn't necessarily equate to breeding success.

One of the questions the researchers eventually hope to answer is to what extent super-breeder characteristics are hereditary. As Ballard told the Antarctic Sun, "There's still a huge amount of mystery when it comes down to it."

Source
Super breeders by Peter Rejcek, 18 February 2011, The Antarctic Sun

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