Historical clue formulations

• Border collie, by nature — 2020-04-18
• Border collie, when working — 2015-09-09
• Collie, e.g. — 2009-09-25
• Sheepdog, by training — 2002-08-27
• Cowboy, for one — 2002-03-29
• Field manager? — 1999-01-29
• Cowboy, at times — 1998-03-15
• Gaucho — 1997-09-27
• Ranch worker — 1997-06-05