March 22, 2011
If you held a short race between a silver Y moth and a European songbird, the bird would win hands down. These birds, such as warblers, thrushes and flycatchers, can fly about three times as fast as the silver Y moth. But when it comes to long-distance migration, from northern Europe to the Mediterranean or sub-Saharan Africa and vice versa, the moths have no problems keeping up with the birds, say scientists in Sweden and the United Kingdom in a new study in the Proceedings of the Royal Society B.
The researchers tracked silver Y moths in England and songbirds in Sweden during their nocturnal spring and fall migrations from 1999 to 2008, using a special kind of radar. They found that although the birds’ airspeed was about three times faster than the moths’, the two groups speed over the ground was about the same, ranging from 18 to 40 miles per hour.
“We had assumed that songbirds would travel must faster over the same distance,” said study co-author Jason Chapman, of Rothamsted Research in the United Kingdom. “It was a great surprised when we found out the degree of overlap between the travel speeds—the mean values are almost identical, which is really remarkable.”
The moths and birds take different approaches when migrating over these long distances: The moths wait for a favorable tailwind, or seek out an altitude with the fastest air, to give them a push towards their final destination. The birds, however, aren’t so picky and rely on their wings to get them where they need to go.
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