Scientists uncover penguins' winter adventures

For the six harshest months of the year, macaroni penguins leave their colonies and disappear out to sea. But where do they go and how do they survive?

These questions have left scientists guessing, because until now tracking technologies have been too cumbersome to use over such a long period and could endanger penguins by hampering their swimming ability.

Now, Charles Andre Bost and colleagues have used high-tech tracking devices to determine the incredible journeys the penguins take, and even find out what they eat on their adventures. This latest research was published today in the Royal Society Journal Biology Letters and has important implications for the conservation of a species whose numbers are declining worldwide.

The team attached miniaturised sensors to the legs of 12 adult penguins, using these to monitor movement. The sensors work by calculating the animal's position by changes in light intensity related to the season and time of day, and revealed that the penguins travelled incredible distances of over 10,000 kilometres, sometimes covering more than 2000 kilometres in a single month. All the penguins remained at sea for the whole six months without once returning ashore.

Bost and his team also made a surprising discovery about what the penguins ate to survive during the winter. Importantly, the data collected showed how the birds all stayed and foraged for food within an unexpected area of the Indian Ocean called the Polar Frontal Zone, where their normal diet of Antarctic Krill which isn't found.

This is the first time that the movements of a penguin species have been tracked at sea throughout the winter months. Macaroni penguins are the most numerous penguin species, but their numbers have declined in this region over the last 20 years, says Bost. 'Such winter information is a crucial step for a better integrative approach for the conservation of this species whose world population is known to be declining,' he says, and revealing what these penguins really do get up to in winter will help with conservation efforts of other species too. 'Delineating the foraging areas during the inter-breeding period is a key step for a better understanding of predator biology and their conservation.'