Can mean “the alternation of two musical tones a diatonic 2nd apart” or “a seem resembling a musical trill.” The flute-like trill on the wood thrush is Probably the most lovely song of any North American chook. The descending trill of its relative the veery isn’t far too shabby, either. https://bookmarksurl.com/story3709116/how-birdwithmostwords-com-can-save-you-time-stress-and-money