LL Wolf 1964 Aimophila humeralis July 23 Cañon de Lobos 9mi E. Guanajuato, Morelos Mexico 09:15 - Chatter introduced by 2 pitza notes from area #1. 09:21 - Chatter introduced by 2 pitza notes from area #2. Sounded like pitza notes began further uphill than chatter location. 08:xx - New series of pitza notes that are given by at least two birds. Then chatter that sounds like two birds singing same part (see below). Then several pitza notes followed by normal chatter. 09:26 - 2 chatters from area of tree #3. 1st the two birds did not synchronize exactly & one still calling hill notes ........ while bird giving whack peet za peet za stopped, so both participate & give different parts. 09:29 - Bird song L ......... Song followed by pitza notes from area #3. Again #2 chattered. 09:32 - Bird in area #3 - Uphill calling pitz - single notes giving at intervals of about 3 secs., but becomes irregular. 09:34 - Pitza + chatter (short) from area #2. This followed by longer chatter from area #2. Then quiet. 09:35 - Two pitza notes introduce long chatter from near tree #3. Then pitza note + short of chatter followed by more pitza notes from area #1 09:36 - 2 birds fly out of tree #3 & pitza sharply. Then chatter by 2 pairs simultaneously - one to Sg tree #3 + one to W, death, not really normal & hear several times L ........ call. This is only time I have heard this call. Then chatter + quiet.