Faces in the crowd: how do penguins identify their chicks?

King penguins breed on sub-Antarctic shorelines of the southern hemisphere where the colony head count can be in tens of thousands or more. On land the male and female of each pair take turns at incubating the egg on their feet, and going fishing. Yet they manage to find their way back to their partners among the huge crowds. 

It would have to be like trying to find your partner in a section of the MCG where everyone is wearing black and white Collingwood jumpers, matching beanies and yellow flippers. You don’t have a seating location but you know they are somewhere in this area of over 10,000 identically dressed, noisy fans, who are all also on the look-out for partners and kids. So how do the penguins find their partners in a large throng? 

Dr Peter Dann is Director of the Penguin Foundation, research manager at Philip Island Nature Parks and an honorary researcher at the University of Melbourne. 

He says that studies have shown the adults and chicks find each other acoustically.

“That means penguins call out to each other and rather amazingly can recognise each other’s calls among the noise. 

“It’s called the ‘cocktail party effect’, a term used by scientists who first explored the ability for discernment of certain sounds amid a range of background noises in King penguins. 

“Imagine yourself at a noisy party. If your name is being mentioned in a conversation across the room it’s likely you’ll pick that up. It’s as if you can filter, but also scan for recognisable sounds.

“In our research we’ve watched adult King penguins in conversation on Heard Island, and one of my masters students explored parent-chick vocal recognition in Little penguins in a maze. 

“The results showed that parents could recognise the sound of their own chicks, and this is an adaptive feature ensuring a penguin feeds its offspring and not someone elses. Interestingly, the chicks appeared not able to recognise their parents. Its possible the chick’s vocabulary and acoustic abilities have yet to develop,” Dr Dann says. 

Penguins are particularly suited to such research because unlike many other bird species in which males and females look distinctly different, penguins look like clones. 

So how does a female penguin choose a mate and what makes one male penguin more alluring than the next identical guy? 

“Male penguins tend to be slightly bigger and have slightly longer, deeper beaks than females,” Dr Dann explains, “and they perform a ‘courtship’ display in front of nesting burrows. Observations suggest the quality of his burrow may be a factor in the female’s choice. Bigger male penguins are popular with females, possibly because this suggests they’re good fishers. A deeper voice may also help make them more distinctive, and being fatter could be another attractive trait.”

Voice also asked Dr Dann about penguin navigation, as they have been known to cover large distances, sometimes in the dark. 

“Like other migrating birds scientists suspect they have an ability to sense and use magnetic fields for navigation, as well as celestial cues. But penguins also use landmarks. We have seen it with the Phillip Island penguin population: when one of the three light towers at the Penguin Parade has blown a bulb they will land onshore at a predictably different point. In the wild there is suggestion they use the stars as a landmark. And if it’s foggy they will wait ‘til the fog lifts before they come ashore. We think this is because they cannot see any landmarks on the shore to orientate them to their tracks.”

One of Dr Dann’s current research projects with Victoria University researcher Professor John Orbell is focused on developing a new way of cleaning wildlife fouled by oil spills, using a finely ground magnetic powder.

“Sadly there seems to be an oil spill every few weeks somewhere in the world so this is a global problem. Current methods use hot water and detergent but this disrupts the animals’ waterproofing requiring post-cleaning periods of weeks for recovery and hot water is not always available. 

“We’re working on a finely-ground magnetic powder that will remove oil more efficiently and effectively. It works for fur seals, and likely for turtles, and marine iguanas, as well as penguins and we’re very excited at this better approach to caring for damaged wildlife.”

www.penguinfoundation.org.au

www.zoology.unimelb.edu.au