Answer: whistlers

AnswerCrossword Clue
WHISTLERSRefs, at times
WHISTLERS"... Mother" ("Arrangement in Gray and Black")
whistlersA person who whistles
whistlersWHISTLER, one that whistles (to make a shrill sound)
whistlersA robust Australasian and Indonesian songbird with a strong and typically hooked bill and a loud melodious call
whistlersAn atmospheric radio disturbance heard as a whistle that falls in pitch, caused by lightning