Historical clue formulations

• One singing "The Lonely Goatherd," e.g. — 2025-11-11
• Alpine crooner — 2025-01-31
• One in peak singing condition? — 2022-02-02
• One making frequent pitching changes? — 2020-01-26
• One calling from a Swiss mountaintop — 2016-05-23
• Jimmie Rodgers or Tex Owens, musically — 2012-02-26
• Producer of high and outside pitches? — 2009-12-18
• The lonely goatherd, in a "Sound of Music" song — 2005-12-18
• One calling at peak times? — 2005-09-25
• Alpine vocalist — 1994-12-20
• Peak performer? — 1994-12-02