Penguin hunting techniques revealed
Footage has shown an insight to penguin feeding behaviours, revealing that the birds are extremely efficient hunters.
Japanese scientists attached video cameras and accelerometers to free-swimming Adelie penguins off the coast of Antarctica, in order to record intimate details of their hunting strategies.
Accelerometers are a modern device that record indirect signals, such as acceleration of the head, temperature changes in the digestive tract or beak-opening movements – each indicating that feeding has occurred.
The scientists found that the penguins adopted different strategies depending on the type of fish they were hunting.
"We recorded both movies and indirect signals, successfully validating the indirect signals using video footage," explained the study's lead scientist Dr Yuuki Watanabe, from the National Institute of Polar Research in Tokyo.
When hunting krill, the penguins would swim upwards, then change direction at the last moment, making darting movements with their head. This allowed the penguins to feed on krill at a rate of up to two per second.
The scientists also found that penguins would hunt bald notothen fish (Pagothenia borchgrevinki) from below, despite the fish's ability to camouflage against the backdrop of marine ice.
"I was surprised by how the penguins repeatedly captured P borchgrevinki underneath the sea ice. This fish is known to be well camouflaged," said Dr Watanabe.
The research has been published in the Proceedings of the National Academy of Sciences journal.
