How animals navigate the earth’s magnetic field

Animal traits can now be examined using the Swarm magnetic field satellites.

By Berit Ellingsen

Many animal species, both birds, mammals, fish and insects, migrate over long distances. Some travel back and forth across continents or oceans to get where conditions are best according to the seasons.

Despite the fact that researchers have been studying animal migration for decades, we do not yet know exactly how animals find their way over such great distances. It is nevertheless clear that some animals use, among other things, the earth’s magnetic field to navigate.

But since the earth’s magnetic field changes all the time, especially during periods when the sun has many eruptions that create storms in the magnetic field , it has been difficult to investigate how the earth’s magnetic field affects the features of animals.

Now, researchers at the University of St Andrews in Scotland, the British Geological Survey and the University of Western Ontaria in Canada have used the European magnetic field satellites Swarm to calculate the strength and direction of the Earth’s magnetic field along the routes of animal migration.

The strength and direction of the magnetic field

The researchers compared data from Swarm with data from Movebank. This is a free database that contains millions of data over time and place where various animal species have been observed.

Here, the researchers looked at data on tundra geese (Anser albifrons), which spend the spring and summer in Greenland and Siberia and the autumn and winter in Western Europe.

– We used the GPS positions and times when the tundra geese had been observed, and found the measurements from Swarm that were closest to these, says Urška Demšar, at St. Andrews University.

These data were combined with information on the possible impact of the magnetic field from the local geology and ionosphere.

In this way, the researchers were able to calculate the strength and direction of the magnetic field at the places where the tundra geese had been.

Swarm is controlled by a Norwegian

It turned out, among other things, that solar storms and bad space weather caused the tundra geese to follow other routes north than those they usually used.

The new method means that researchers can now combine animal migration data with geophysical information, in order to better investigate how animals find their way on long migrations.

“More data on the magnetic field will give us a whole new set of environmental parameters that we did not have before Swarm,” Demšar told the European Space Agency (ESA).

It is ESA that has developed and manages Swarm, which examines the earth’s magnetic field, the space weather around the earth, and the earth’s interior.

The leader of the work with Swarm at ESA is Norwegian Anja Strømme.