GRONINGEN, Netherlands, April 18 (UPI) -- It's nearly impossible to track the exact migration of songbirds across the Sahara using only human faculties. They are too small, there are too many, and sightings by birders and field scientists are too unreliable.
For some clarity, a pair Dutch researchers attached sensors to several European pied flycatchers, Ficedula hypoleuca, most of which split their time between Europe and tropical Africa. They recovered 27 of the tracking devices, 15 of which possessed usable data.