Off the coast of Awashima Island, a two month-old streaked shearwater chick huddled against its siblings. The weather had been getting colder. Soon, the white-and-brown-winged family would navigate over 4,000 miles of foreign terrain and featureless ocean until arriving in Australia. For now, however, the vacation must wait.
A group of neuroscientists and ecologists from Doshisha University and Nagoya University approached the burrow. They had questions about the chick’s travel plans. Most notably, how does it know where it’s going?
You probably know that many animals rely on their sense of smell to keep track of where they have been and where other animals are, but how do other animals find their way? How do they navigate when it is cloudy? On the other hand, certain animals migrate, or move from one location to another, often covering hundreds or even thousands of kilometers annually. Since it doesn’t seem possible for animals to accurately repeat such lengthy journeys using just their sense of smell, scientists have been searching for evidence of alternative senses that animals might have. Scientific research is being done to determine whether animals can repeat their lengthy travels by using the Sun, Moon, Earth’s magnetic field, or landmark recognition.
Famous for their extraordinary long-distance navigational skills are homing pigeons. They were used to transmit messages over enemy lines in both World Wars I and II because of how trustworthy their “homing” was. Do homing pigeons carry a map and compass with them to help them find their way even on overcast days?
A compass could be useful if you were lost in the middle of the forest and couldn’t see the sun to determine which way to go. A magnetic compass needle points roughly north and south when aligned with Earth’s magnetic field; it can also be used to determine east and west. People have been using magnetic compasses to find their way for approximately 1,000 years because they function fairly well.
Birds rely on magnetic fields to navigate long distances
It’s not the first time scientists have demanded answers from birds. In 1942, William Keeton’s parents gave him his first homing pigeons for his ninth birthday. He cherished the regal bird and forwent chores and school work to train the bird. In races, however, the bird rarely won. Such shame at such a young age can only drive a person to do one thing: become a scientist.
After one thing led to another, Keeton, who was a biology professor at Cornell University at the time, began attaching magnets to pigeons in 1965. Keeton postulated that magnetic field alignment is crucial for navigation since earlier research had demonstrated that certain animals align their bodies with magnetic fields. He was correct. The polarized pigeons were clumsy navigators at best.
Over the course of the following few decades, scientists studied how migratory birds identify magnetic fields. The majority of scientists disapproved of the theory that birds concealed a compass beneath their wings. That, of course, would be silly. The bird’s eyes and brain contained a magnetically sensitive protein that functioned as a compass.
At first glance, that seems to be the end of the story: Birds navigate by magnetic fields, and they have a special protein that allows them to detect magnetic fields. However, one question lingers: How do the birds translate a magnetic field into direction? This is what the scientists behind the recent study hoped the streaked shearwater chick could answer.
Detection is not sufficient for direction
Imagine losing a cell phone while visiting a friend. Your friend calls your phone. You can’t immediately place the source of the soft ringing sound that you hear. Your head is tilted slightly to the left, then right. The couch!.
In this case, the ear picked up the sound waves from the ringing phone right away. The location of the phone, however, was not immediately clear. The brain analyzed minute differences in each incoming sound wave. After gathering information, it gave a direction, saying, “The phone is facing the couch.” “ You used this information to navigate toward the phone. Simply put, there are three steps involved in navigation: the first is identifying a landmark (sound waves), the second is giving the landmark a direction (couch-wardly), and the third is choosing which way to go (toward the couch). Your movement is guided by the direction rather than the sound of the phone.
The magnetically sensitive protein allows birds to detect a landmark (magnetic fields), but there must be a neural mechanism that assigns direction. Scientists have reported that head direction cells activate when an animal’s head points in a particular cardinal direction (north, south, east, west). Moreover, head direction cells were recently reported in the medial pallium of birds — a region similar to the mammalian hippocampus or parahippocampus, which are both involved in assigning direction.
The investigators of the streaked shearwater chick postulated that the medial pallium is in charge of determining the direction of magnetic fields based on those earlier investigations.
FAQ
Do birds have magnets in their brains?
Are birds magnetic?
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Do birds have a compass in their head?