King penguins navigate in darkness to find their breeding spot in a colony of up to 300,000 penguins, say scientists. These images show the challenges penguins face in finding their way through the huge colony.
"Imagine you were in a huge concert with hundreds of thousands of people standing in front of you, it's totally dark but you have to find your friends," says Dr Anna Nesterova, who is trying to unravel the mysteries of how king penguins orientate on land.
King penguins do not build nests but incubate a single egg on their feet. Breeding pairs defend a small spot in the colony known as an "attachment place", which is approximately a metre square.
Penguins return from foraging trips at sea and need to come back to their mates and chicks within the colony as soon as possible, even if it means doing so in poor light.
The study reveals for the first time, that adult penguins can find their way in the colony in complete darkness with no moonlight or starlight to help them.
The researchers studied penguins colonies on the subantarctic islands of Kerguelen and Possession. Colonies where penguins gather to raise young can number hundreds of thousands of birds at a time.
The team used tracking technology to study the penguins' movements. One method used satellites and global positioning systems (GPS). Another used tags implanted in the birds with underground antennas situated around the colony on Possession Island.
Scientists found older, more experienced parents completed more night time manoeuvres than young parents. This showed an important learning element to colony navigation. The research team was made up of scientists from France, Norway and the US.
How penguins navigate on land is still something of a mystery. Scientists suggest they use a suite of cues to navigate, including visual, acoustic and olfactory signals. Here a penguin calls out to a partner.
Sometimes, penguins have to walk more than a kilometre to reach their chicks.
Experiments on 10-month-old chicks have also revealed that, even at a young age, chicks have a good ability to navigate to their attachment place in the colony.
As well as revealing how king penguins orientate, researchers want to find out how the penguins choose their place in the colony, if it is connected to place of birth and whether the male or the female selects the location. And the birds are curious too.
The research team included Anna Nesterova, Emeline Pettex and Francesco Bonadonna from CEFE-CNRS, Montpellier, France; Celine Le Bohe at the University of Oslo, Norway, and David Beaune and Yvon Le Maho from IPHC-CNRS Strasbourg, France.
The research was funded and supported by the Institute Polaire Franšais - Paul-Emile Victor (IPEV) in France, Terres Australes et Antarctiques Franšais (TAAF), and National Science Foundation (NSF) in the US.