“Bad space weather” refers to the sun spitting out vast globules of charged plasma towards planet Earth which has the power sometimes to knock out communication satellites and also the power to mess up the Baltimore Oriole’s navigation system when they migrate. I understand this to be because bad space weather interferes with the birds’ detection of the Earth’s magnetic field.
In a study, scientists used radar data going back 23 years to track several species of birds as they used an American migratory corridor across the Great Plains which is about a thousand miles long from Texas to North Dakota.
They cross-reference this information with readings which measured the change in the Earth’s magnetic field. These readings allowed them to identify changes in space weather.
When there was severe space weather, they discovered that there were reductions of up to 17% in the number of migrating birds in that area. And the birds that did migrate during these times of bad space whether appeared to experience difficulty in navigating.
And during these episodes in the autumn, the researchers found that birds appeared to drift on the wind more frequently. This is in contrast to birds when they typically battle crosswinds to keep on track.
It is believed that humans cannot detect the Earth’s magnetic field but it seems that many animals can including by the way domestic cats. It is believed that domestic cats use the Earth’s magnetic field to help navigate home. It’s a work in progress theory. Note: perhaps some humans can detect the magnetic field which makes them better navigators. I instinctively know where north is!
The lead researcher in the study is Eric Gulson-Castillo of the University of Michigan.
The Times – which reported on this and which is the source of this article – say that the Earth’s magnetic field is created by the “churning of molten iron beneath the planet’s crust”.
The science correspondent, Rhys Blakely (The Times), states that there are three aspects to this magnetic field which might help animals to navigate:
- It’s intensity differs from place to place which might be detected by birds to help them navigate;
- A potential navigational aid would be the angle between magnetic and true north and
- It may be the case some animals can detect the “magnetic inclination” which would allow them to know how far north they were. This is the angle between the magnetic field and the ground. Rhys tells us that “the field is perpendicular to the surface of the earth at the magnetic poles, and runs parallel to the surface of the equator.”
The study is published in the Proceedings of the National Academy of Sciences
