Historical clue formulations

• "____-hoo!" — 2023-08-29
• "___-hoo!" — 2022-06-18
• ___-hoo — 2021-09-22
• "___-hoo!" — 2020-02-23
• "___-hoo!" — 2017-09-10
• "___-hoo!" — 2017-06-14
• "___-hoo!" ("Hello!") — 2016-08-22
• ___-hoo — 2016-04-22
• Start of an attention-getting cry — 2014-08-16
• "___-hoo!" — 2013-07-01
• "___-hoo!" — 2012-08-30
• Start of an attention-getting call — 2012-04-01
• ___-hoo — 2010-10-15
• "___-hoo!" — 2008-03-17
• "___-hoo!" — 2008-02-06
• "___-hoo!" — 2006-05-09
• "___-hoo!" — 2004-05-30
• "___-hoo!" — 2003-01-12
• First half of an attention-getter — 2001-02-25
• "___-hoo!" — 2001-02-06
• ___-hoo — 1999-01-17
• "Hoo" preceder — 1998-06-28
• ___-hoo — 1998-04-23
• ___-hoo — 1996-04-28
• "_____ hoo!" — 1995-02-14
• _____-hoo — 1994-04-13