Can suggest “the alternation of two musical tones a diatonic next aside” or “a audio resembling a musical trill.” The flute-like trill in the Wooden thrush is Probably the most attractive tune of any North American fowl. The descending trill of its relative the veery isn’t far too shabby, either. https://worldsocialindex.com/story3715215/a-simple-key-for-birdwithmostwords-com-unveiled