North American migratory birds have shrunk in size and grown longer wings in the past forty years.
They are also migrating earlier in the spring.
Could global warming be behind these changes? Maybe smaller bodies, longer wings help them arrive faster to their breeding grounds?
Researchers recently found that birds are indeed changing size. They are also changing their migration timing. But one has nothing to do with the other.
So if a warming climate is not causing this, what is?
Are the birds somehow adapting in a way that allows them to fly faster without causing them to overheat or lose too much water? Smaller bodies lose heat more quickly, and remain cooler for longer - this could be an advantage during global warming?
So far, researchers have not found any connection. We don't know but are trying to find out.
Original article:
Original study:
Widespread shifts in bird migration phenology are decoupled from parallel shifts in morphology