subject to various manipulations once the experiment gets under <br />> way. <br />> Inside the huts, robins are released in special cages called <br />> Emlen funnels <br />> <http://www.csuPomona.edu/%7Ed0moriarty/orni/Z329%20Emlen%20funnel.pdf> <br />> . Thermal paper linings in the funnels record the scratches the <br />> birds' feet make as they scrabble upward. In the absence of other <br />> navigational cues, namely sun and stars, the birds will orient to <br />> the Earth's magnetic field, which is detectable through the <br />> wooden walls of the huts. They will take off toward the north, <br />> marking the paper in their attempt to escape. <br />> Or so they had in thousands of previous experiments, including <br />> Mouritsen's own Ph.D. research conducted in rural Denmark. But <br />> this time the exercise went immediately awry. <br />> The robins seemed to have no idea where north was. "The birds <br />> basically jumped in random directions every spring and autumn for <br />> three years," Mouritsen says. <br />> Puzzlement gave way to desperation. The scientists changed the <br />> robins' food, their cages, the shape of their cages, the light, <br />> the daylight cycle. Nothing affected the randomness of the <br />> scribbles inside the funnels. <br />> Then a graduate student, Nils-Lasse Schneider, <br />> <http://www.uni-oldenburg.de/en/biology/animal-navigation/members/dr-niIs-lasse-schneider-postdoc <br />> suggested using aluminum Faraday cages. A Faraday cage <br />> <http://science.howstuffworks.com/faraday-cage.htm> is basically <br />> a grounded metal box. It doesn't screen out the Earth's powerful, <br />> static magnetic field?but it would shield against weaker, <br />> time-dependent electromagnetic fields such as those generated by <br />> electric appliances and electronics. <br />> _I would have laughed the suggestion off three years earlier,_ <br />> Mouritsen admits. Instead, they installed aluminum Faraday cages <br />> in the huts, grounding them to wires screwed to the outside. Once <br />> again, the scientists released the robins in the Emlen funnels. <br />> Miraculously, it seemed to Mouritsen, the robins flew north. <br />> Three years behind schedule at this point, the scientists threw <br />> themselves into conducting the brain experiment. They identified <br />> -cluster N,_ a part of the robin's forebrain, as the site where <br />> magnetic compass information is processed in the bird's brain. <br />> They published that finding in <br />> <http://dx.doi.org/10.1038/nature08528> Nature in 2009. <br />> But the weird behavioral hitch resolved by the Faraday cages <br />> still had the scientists scratching their heads. <br />> The Simple Turn of a Screw <br />