|It looks determined, but is this Adelie |
penguin at Palmer Station a super-
breeder? Photo by Johnny Shaw.
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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."
Super breeders by Peter Rejcek, 18 February 2011, The Antarctic Sun