Household appliances, power lines, cell phones and many other human technologies emit weak electromagnetic waves. For us humans, this electrosmog is considered uncritical within the permissible limits. On the other hand, the artificial electromagnetic fields can have serious effects on animals that orientate themselves on the Earth’s natural magnetic field. A study now shows that mosquito bats exposed to weak electrosmog for 30 minutes still had problems with orientation even several hours later. The results suggest that electromagnetic interference fields affect animals beyond immediate exposure.
Many animals, including migratory birds and bats, orientate themselves, among other things, on the Earth’s magnetic field when they migrate. This means they also react sensitively to other magnetic fields, such as those generated by human technologies. It is already known that electromagnetic radiation, such as that caused by radio antennas and household appliances, can disrupt the internal compass of migratory birds. Even low intensities that are well below the limit values considered safe for humans are sufficient.
Disturbed inner compass
Now a team led by Oliver Lindecke from the University of Oldenburg has discovered that bats are also disturbed by electrosmog. For their experiment, the researchers caught wild mosquito bats (Pipistrellus pygmaeus) in Latvia and exposed some of the animals to weak broad-band radiation in the frequency range from 10 kilohertz to 300 megahertz for 30 minutes at sunset the following evening. A few hours later, they released the bats one at a time and observed which direction they flew. Would they take off in the direction that corresponded to their natural migration route?
The result: “While the bats in the control group oriented themselves normally, the bats that had previously been exposed to electromagnetic interference signals showed a random flight direction when taking off,” report Lindecke and his colleagues. Apparently the animals’ sense of direction was confused. Previous studies by the team had already shown that mosquito bats readjust their magnetic compass every day at sunset, if possible. In the current study, the artificial electromagnetic fields apparently disrupted this recalibration.
Ongoing effects
But even if the bats were able to watch the sunset undisturbed and were only then exposed to the electromagnetic noise, their sense of orientation suffered. Although the animals were only exposed to the interference field for a short time, this effect lasted for several hours. “This effect really surprised us,” says Lindecke. “Studies on migratory birds indicate that their magnetic sense immediately works again when electromagnetic noise is no longer present.” Until now, it was assumed that electromagnetic interference fields could only affect migrating animals directly if they came close to them during their migration.
“However, our results suggest that even short exposures can have serious effects that last longer than the electromagnetic noise itself,” says co-author Richard Holland from Bangor University in the UK. Accordingly, electrosmog could affect the behavior of animals in a more complex way than previously thought. Increasing urbanization and the increasing spread of wireless technologies, which increasingly create artificial electromagnetic fields, could therefore disrupt the migratory behavior of wild animals. “The current limit values are intended to protect us humans, but do not take wildlife into account,” says Lindecke. “Our results show that wildlife can be impacted well below these thresholds.”
Source: Oliver Lindecke (University of Oldenburg) et al., Science, doi: 10.1126/science.adq4418