Biologists provide evidence that maximum body size in birds is constrained by the amount of time it takes to replace the flight feathers during molt. Why aren't birds larger? Fifteen-kilogram swans ...

Scientists have discovered a nearly complete skeleton of a baby bird only about the size of a cockroach—perhaps the smallest baby bird fossil ever found from the dinosaur era, according to a new paper ...

Birds across the Americas are getting smaller and longer-winged as the world warms, and the smallest-bodied species are changing the fastest. Birds across the Americas are getting smaller and ...

Wow. A newly discovered flying bird species had a wingspan that stretched 24 feet long—as big as some aircraft. That’s pretty much a flying giant in the sky that’s twice as big as anything that can ...