Researchers found that the birds speed up during spring because arriving late to their breeding grounds can affect their reproductive success.
Past studies have shown that migrants take shorter breaks in spring, but it is harder to tell whether they also move faster in the air.
Researchers at the University of Oklahoma in the US used high-tech weather surveillance radars and found that birds did indeed fly faster in spring and compensated more for crosswinds that could blow them off course.
"Many migration studies look at a few individuals, maybe on the scale of hundreds, but with radar, we're now documenting the behaviours of millions of individuals on a given night," said Kyle Horton of Oklahoma.
"That's a lot of data, and when you do see flight behaviour results that are regionally or seasonally different, it is quite compelling," said Horton.
He hopes birds' ability to adjust their migratory behaviour for different conditions will buffer them against the effects climate change, which may cause large-scale shifts in wind intensity.
The study was published in journal The Auk: Ornithological Advances.
