Have you ever wondered as to how birds travel in winter without any navigation system?

Researchers from the Baylor College of Medicine have found that birds have their own built-in GPS system that uses the earth's magnetic field to guide them when they are flying south for the winter. They found this while analysing certain cells in the pigeon's brain.

"We know birds and many other animals can sense the magnetic force; behavioural studies show that birds fly along magnetic routes during seasonal changes," said Dickman, professor at Baylor College of Medicine, in a statement. "It is still unknown what exactly acts as a receptor within the bird; however, in our current study we are able to show how neurons in the pigeon's brain encode magnetic field direction and intensity. This is how we believe birds know their position on the surface of the earth."

Researchers had used electrodes in one brain area, known as the vestibular nuclei, to record activity when the bird was exposed to a changing magnetic field. They found that when the birds travel certain areas in the brain gets activated. These cells get activated when a particular area of the inner ear, known as the lagena, is exposed to a magnetic field. Without it, several of these corresponding areas in the brain show no activity.

"The cells responded to the angle and intensity of the magnetic field. Some cells were more sensitive depending on what direction we aimed the magnetic field around the bird's head," said Dickman.

Researchers believe that the vestibular neurons are part of the receptor network that detects and sends information about the direction and intensity of the earth's magnetic field to the rest of the brain. It is believed that birds use this information to create spatial maps.

"Birds give us a unique opportunity to study how the brain develops these spatial maps and the receptors that feed into it because they have such a great ability to navigate," said Dickman.

"Birds actually have more similarities to the human brain than not, so understanding these characteristics could eventually lend itself to understanding how we create spatial maps and those disorders that affect these areas of the brain," he added.