Sentence:  Ah, sad and strange as in dark summer dawns / The earliest <WSD>pipe</WSD> of half-awaken'd birds / To dying ears, when unto dying eyes / The casement slowly grows a glimmering square; / So sad, so strange, the days that are no more. 
Meaning of the word marked with <WSD> tags:  A high-pitched sound, especially of a bird. (from 18th c.)