The magnetic sense of migratory birds is probably based on the protein cryptochrome 4, and a genetic study has now provided further support for this theory. A team of researchers from the University of Oldenburg and the Institute of Avian Research in Wilhelmshaven compared the genomes of several hundred bird species and found that the gene sequence for cryptochrome 4 has changed considerably during evolution. This suggests that cryptochrome 4 was selected to adapt to different environmental conditions. A possible explanation is that cryptochrome 4 acts as a sensor protein. The study was published in the journal Proceedings B of the Royal Society.