Foraging

The yellow-eyed penguin is a long distance athlete.

They are capable of travelling up to 27.5 kilometres daily looking for fish and then swimming back to shore before walking long distances up hills to their nests.

They are amazing underwater marathon swimmers. Helped by their wings – which are more like flippers – and a body shape similar to seals and dolphins, they can dive down to 120 metres deep, holding their breath for up to four minutes.  This is necessary because it is believed that they mainly feed on the sea floor. 

Researchers have found that yellow-eyed penguins on the Otago Peninsula forage on average 19.9 km from their breeding sites with the maximum range of 27.5 km. Then, they have to swim another 19.9 km to 27.5 km back home.  

Timewise, a yellow-eyed penguin often has a 14-hour working day at sea, 10 hours of travel to and from the fishing grounds and four hours of feeding. 

This is a ‘map’ of travel where the penguins appear to use underwater landmarks to guide them to the best foraging areas (thanks to Thomas Mattern). 

How did the researchers find out where and how far the yellow-eyed penguins go at sea? 

They used two types of data loggers: miniature GPS loggers recorded geographical position and dive depth at set intervals, while time-depth recorders (TDRs) recorded only dive depth. They also found that the birds often dived for food at the same places on the sea floor.