Magnetic compass of birds adversely affected by AM radio EMI

Below a certain threshold value, “electrosmog” has no impact on biological processes or even human health. That was the state of scientific knowledge until now. But for the first time, a research team led by Prof. Dr. Henrik Mouritsen, a biologist at the University of Oldenburg, has been able to prove that the magnetic compass of European robins fails entirely when the birds are exposed to AM radio waveband electromagnetic interference — even if the signals are just a thousandth of the limit value defined by the World Health Organization (WHO) as harmless.

Based on seven years of research by nine Oldenburg scientists, in cooperation with Prof. Dr. Peter J. Hore of Oxford University, the findings are now available in a paper published in the latest issue of the journal Nature , which made it the cover story of its May 15 issue.

This interference does not stem from power lines or mobile phone networks, Mouritsen stresses, explaining that electromagnetic interference within the 2-kHz to5-MHz frequency range is mainly generated by electronic devices. “The effects of these weak electromagnetic fields are remarkable: they disrupt the functioning of an entire sensory system in a healthy higher vertebrate.”

“Over the course of seven years we carried out numerous experiments and collected reliable evidence, in order to be absolutely certain that the effect actually exists” Mouritsen said. The most disorienting electromagnetic noise had frequencies matching those produced by AM radio stations and small devices like electronic article surveillance — those little magnetic tags for clothing at department stores.

It all started when researchers were surprised when robins kept in wooden huts on the Oldenburg University campus were unable to use their magnetic compass. After testing for other environmental causes, they covered the wooden huts, along with the orientation cages they contained, with sheets of aluminum. Suddenly the birds' orientation problems disappeared. Considering the potential importance of the finding, Mouritsen and his team performed a large number of experiments to provide evidence of the effect they observed and collected reliable evidence including double-blind studies.

The magnetic compass of the robin did function in orientation cages placed 1 to 2 km outside city limits, where the level of EMI is low, without any screening. “These findings should make us think — both about the effects on migratory birds as well as about the potential effects for human beings, which have yet to be investigated,” Mouritsen concludes.