WAS KNOWN TO: Build nests out of plant matter, saliva and other birds' feathers.
NOW KNOWN TO: Procure those feathers by ripping them off other birds' backs, in flight.
WE KNOW THIS BECAUSE?: Ornithologist Bret Whitney of Louisiana State University saw them do it. The birds, he reports, circle high above their Amazon palm-grove homes until "striking their victim in the middle of the back and tugging at feathers with the bill...to dislodge a mouthful." The swifts favored parrot and pigeon feathers. Most victims, Whitney notes, "react only slightly."