Japanese environmentalists miniature cameras attached to the heads of several Adelie penguins, which allowed them to find out the secrets of hunting birds and count the number of fish and krill are caught in the middle of one dive, according to a paper published in the journal Proceedings of the National Academy of Sciences.
Food habits of many birds, mammals and other vertebrates are large scientific mystery. The reason for this is their habitat — marine life is extremely difficult to find in the interior of ocean waters, and even harder to keep track of their movements and the kind of food they prefer to use and how do they obtain it.
Yuki Watanabe (Yuuki Watanabe) and his colleague, Akinori Takahashi (Akinori Takahashi) from the National Institute of Polar Research in Japan Tahikave fill one of these gaps by examining the diet and hunting habits of Adelie penguins (Pygoscelis adeliae) with specially adapted microchamber and accelerometers.
To observe the behavior of the birds the authors have collected some 30-gram autonomous cameras, which can operate at low temperatures and high speeds for 90 minutes. Then they caught a few birds on the beach near the harbor fukuro in Queen Maud Land (Antarctica) and attached to their heads camera, and acceleration sensors.
During the collection of their feathery "helpers" researchers selected only those birds that have already hatched chicks. As expected Watanabe and Takahashi, parents chicks were sent back to their offspring after hunting in the sea, which would allow ecologists to remove the camera and accelerometers and analyze the collected data.
Adventure researchers completed successfully — 14 of 15 birds have returned to his native shores, along with the attached scientific instruments. Scientists have once again caught the Penguins withdrew the cameras and sensors, and analyzed the contents of their stomachs.
It turned out that Pygoscelis adeliae prey mainly on two kinds of victims — small fish and krill Pagothenia borchgrevinki family of Euphausia.
According to the video from the "on-board" of the camera on the head of birds, penguins practiced two different strategies to catch fish and shellfish. Typically, penguins fished only in the surface layers of the water, without risking to fall in great depth. On the other hand, the birds caught krill and small, and in deep water.
Feathered hunters acted prudently enough — they have carefully selected victims, preferring to attack the large schools of fish and crustaceans, and rarely returned to the surface without extraction. In some cases, the fish did not even notice the approaching birds, and did not try to escape from it. With this Penguins quickly fill your stomach — on average, they caught 250 fish shrimp or 30 and a half hours of hunting.
Watanabe and Takahashi believe their technique could be used for monitoring and for other species of Antarctic birds and animals, periodically returning to the land. These observations will help to understand how the fragile ecosystems of the Arctic Circle, and that may interfere with their normal work under climate change, the scientists conclude.