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.
The results suggest the species sometimes opt for a direct flight across the world's largest non-polar desert, flying between 40 and 60 hours straight.
The new data showed that most pied flycatchers fly directly across the Sahara in the spring, but make a lengthy journey across the sea in the fall -- a detour around the massive sand pit.
Janne Ouwehand and Christiaan Both, scientists at the University of Groningen, published their findings in the journal Biology Letters.
"Our data contradict claims that passerines cross the Sahara by intermittent flight and daytime resting," the researchers wrote in their study. "The frequent occurrence of long non-stop flights to cross the desert shows migrants' physiological abilities."
Ouwehand and Both hope future research will reveal those physiological abilities in detail and help explain why non-stop migration flights across the Sahara aren't the preferred strategy for other species.