While it's clear that communication tower wires and skyscraper windows are deadly for migrating birds, researchers and birders have long suspected that the electromagnetic waves erupting from all sorts of human devices might disrupt birds' inner compasses, too. And there's finally evidence that these signals do have an effect—on European robins, at least.
As Nature reports, a team of German scientists discovered several years back that captive robins couldn't orient themselves properly in the direction they should be flying for migration. Normally, this is a no-brainer for the birds, which use Earth's magnetic field to faithfully guide them to migration destinations. The team suspected electromagnetic waves might have something to do with it, and they designed a double-blind study to find out for sure.
The birds, which were already kept at the university's campus for research, lived in wooden huts, and first, the researchers coated them in aluminum to prevent any waves from getting through. As they suspected, once those noisy signals were blocked out, the birds' navigational abilities were restored, Nature says. The researchers repeated the experiment several times over a period of years, turning the aluminum boundary on and off, recruiting students who didn't know whether they were working with the control or experimental group of birds, just to make sure. Their results stood up
The problematic frequencies, they found, occurred between 50 kilohertz to 5 megahertz, Nature reports. This, ScienceNOW explains, is the range that includes AM radio stations and some small electronic devices—like the security tags that stores put on clothing items.
Animals, the scientists point out, are likely have some work-arounds to prevent our electromagnetic noise from throwing them too far off course. Ornithologists know, for example, that birds can switch off their navigational system in places where the Earth's magnetic field naturally distorts, ScienceNOW says.
On the other hand, Europe's migratory bird populations are declining. While most of that is attributed to habitat destruction, it is possible that electromagnetic noise is playing a role. It can't be helping.