07 April 2011

Penguin mothers get better with (middle) age

AUSTRALIA - As I leave my younger years behind, it is encouraging to find out that the middle-aged can do some things better than the young ... even if the researchers were looking at little penguins, not people.

An international research team has found that while middle-aged female penguins spent less time in the water, they were more successful at finding food compared to younger and older generations.

The researchers investigated the relationship of foraging performance with age in female little penguins at Phillip Island, Victoria. They attached tiny computers to the backs of 19 breeding females for one foraging run and monitored aspects of the penguins' diving ability.

Their findings, reported in the journal PloS One, suggest middle-aged penguins forage better than young or old ones because good physical condition and foraging experience could act simultaneously.

Dr Andre Chiaradia of Phillip Island Nature Parks, one of the researchers, said, "Middle-aged females spent less time under the water with less diving effort."

"But while diving, they had better hunting tactics so they were more efficient at finding food for their offspring."

The older penguins had learned to chase prey from the bottom, using their black backs as camouflage, while the younger ones approached the fish from above, exposing their white bellies and alerting the fish to their presence.

Dr Chiaradia added that middle-aged penguins were fortunate because they had similar strength in the younger penguins but the wisdom of the older ones.

"These factors seem to be acting together to make middle-aged penguins better at fishing,” he said.

"This information is especially relevant in years of low resource availability and probably influences the response of penguins to years when food is hard to find.” 

Old birds show young mums a few tricks by Leigh Dayton, 6 April 2011, The Australian
Middle-age penguins topple youth, 8 April 2011, e-Travel Blackboard

PloS One citation
Does foraging performance change with age in female little penguins (Eudyptula minor)? Zimmer, I., Ropert-Coudert, Y., Kato, A., Ancel, A. and Chiaradia, A. PloS One 6(1). 25 January 2011.

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