How the World Works - Magnets

Our inquiry this term started with a  wondering, as all good inquiries do - Hamish's wondering - how do birds navigate when they migrate? He wondered this after learning about how Maori used the stars to navigate in his Matariki research.



Watch the video again to find out about this.

What scientists have found

Now read a bit more about what scientists are doing.

Birds Can "See" Earth's Magnetic Field

John Roach
for National Geographic News

September 27, 2007

To find north, humans look to a compass. But birds may just need to open their eyes, a new study says.

Scientists already suspected birds' eyes contain molecules that are thought to sense Earth's magnetic field. In a new study, German researchers found that these molecules are linked to an area of the brain known to process visual information.

n that sense, "birds may see the magnetic field," said study lead author Dominik Heyers, a biologist at the University of Oldenburg.

Magnetic Orientation

Human-made compasses work by using Earth as an enormous magnet and orienting a tiny magnet attached to a needle to the planet's north and south poles.

Scientists have thought for years that migratory birds may use an internal compass to navigate between their nesting areas and wintering grounds, which can be separated by thousands of miles. (Related news: "Migrating Birds Reset 'Compasses' at Sunset, Study Says" [April 15, 2004].)

The new research helps explain how this natural compass may work.

Heyers and his colleagues injected migratory garden warblers with a special dye that can be traced as it travels along nerve fibers.

The team put one type of tracer dye into the eyes and another in a region of the brain called Cluster N, which is most active when birds orient themselves.

When the birds got their bearings, both tracers traveled to and met in the thalamus, a region in the middle of the brain responsible for vision.

"That shows there is direct linkage between the eye and Cluster N," Heyers said.

The finding strongly supports the hypothesis that migratory birds use their visual 

The finding strongly supports the hypothesis that migratory birds use their visual system to navigate using the magnetic field.

"The magnetic field or magnetic direction may be perceived as a dark or light spot which lies upon the normal visual field of the bird," Heyers said, "and which, of course, changes when the bird turns its head."

The study was published in a recent issue of the Public Library of Science journalPLoS ONE.

We need to explore magnets ourselves in class to understand more.  

Please, we need magnets to help with this!

What do you think we need to understand about magnets? Make a comment about this.