King penguin parents spend about 14 months incubating their egg, then rearing their chick. They take it in turns to find food, so the strength of their bond is crucial. Biologists want to know how they make this important mate selection, and even how the birds tell a male from a female; the two sexes look almost identical.
Prof Stephen Dobson from the National Centre for Scientific Research in Montpellier, France, playfully sums up his research: "I'm trying to work out what makes a sexy penguin." His studies of the birds on Kerguelen Island have revealed that penguins often struggle to spot a member of the opposite sex.
When the penguins do find a mate that they take a shine to they carry out an intimate dance – stretching their necks from side to side in what appears to be an elaborate embrace. Occasionally, two males will engage in this mating dance, but the pair usually separate when one finds a female partner.
Prof Dobson also found that males on the island in the Southern Indian Ocean often had to compete particularly hard to snag a female mate. He and his team noticed that, during mating season, trios of penguins would "parade" around together. DNA analysis showed that the trios were usually two males pursuing a female.
Prof Dobson’s team, which also includes researchers from the Centre for Functional and Evolutionary Ecology in Montpellier, France, has found that the penguins' bright yellow ear patches play an important role in attraction.
Males with artificially-reduced ear patches seemed to have less success finding a female. Females also appeared to choose males with larger ear patches, and the researchers think that larger ear patches might convey a male's ability to defend his chick and his territory in the crowded colony.
The scientists hope to unpick the evolutionary mystery of how these birds select a suitable partner who will co-operate in the care of their egg and chick. They also hope to find out more about the penguins' natural behaviour to see how they are being affected by environmental change.