Birds often migrate faster in spring than in autumn

The question whether birds might migrate faster in spring than in autumn has been debated for decades, and recently CAnMove researchers Cecilia Nilsson, Raymond Klaassen and Thomas Alerstam decided to use the rapidly increasing number of studies that track migrating birds to test this. 

And their study, published in the American Naturalist, do show a clear dominance of cases where spring migration is faster than autumn migration, in flight speed, stopover duration as well as total migration speed - suggesting that  spring and autumn migrations often constitute quite different evolutionary processes, involving different main selection pressures and adaptive solutions during the two seasons. For the future, first author Cecilia Nilsson hopes that this summary will open up the question of differences between spring and autumn migration and inspire critical tests of what determines migration speed.

Read the article here! (University log-in) or go to the American Naturalist.