Birds Have 'Compass' In Brain Cells Activated As They Turn North
Nerve cells acting like a compass have been found in the brains of young streaked shearwaters, which become active when the migratory bird turns to the north, a team including researchers from Doshisha University announced recently.
Photo Insert: A streaked shearwater
The team says the finding will lead to a better understanding of the detailed mechanisms of the bird's journey from Japan to the Southern Hemisphere across the Pacific, Norikazu Chiba reported for Mainichi Japan. The study was published recently in the US journal Science Advances.
To spend the winter in warmer areas, young streaked shearwaters go straight south from their breeding grounds in Japan without the help of their parent birds. Professors Susumu Takahashi at Doshishsa University's Graduate School of Brain Science and Ken Yoda at Nagoya University's Graduate School of Environmental Studies focused on this characteristic of the bird.
They placed 10 young streaked shearwaters in separate boxes and monitored them with a camera ahead of the winter and examined the correspondence relationship between the direction of their heads and their brain activity.
As a result, the researchers found out that nerve cells called "head direction cells" exist in the birds' brains, and that those cells become active when the birds' heads turn to the north, at a high frequency of about 17 times per second. The same results came back regardless of whether the experiments were conducted indoors or outdoors.
The researchers concluded the birds utilize the Earth's magnetism. According to the group, head direction cells have previously been discovered in the brains of mammals, insects, and other bird species.
The cells show highly frequent activity when their heads turn towards a certain direction. But because cells with highly frequent activity were evenly found for all directions, experts had previously believed the cells had nothing to do with the Earth's magnetism.