Alpine warbler

• Jimmie Rodgers or Tex Owens, musically
• Alpine singer, perhaps
• One calling from a Swiss mountaintop
• Alpine noisemaker
• Alpine show-off
• Old-time country singer, sometimes
• One making frequent pitching changes?
• Producer of high and outside pitches?
• Person who sings like someone in the Swiss Alps

Wiktionary Word definitions in Wiktionary
n. One who sings so that their voice fluctuates rapidly between their normal chest voice and a falsetto, one who yodels.