| sentinels in saltator atricollis (passeriformes: emberizidae). | i studied the existence of sentinels in saltator atricollis in a 'campo-cerrado' (brazilian savanna) during the breeding seasons of 1994-95 and 1995-96. groups of this species consisted of two to seven birds (n = 25). sentinels were present (mean +/- sd) 62% +/- 9% of the time, and most sentinel bouts lasted from less than one to six minutes (although in some occasions for more than 30 min.). overlap of two or more sentinels occurred on average only 3.2% of the time with birds on guard. sentinel ... | 2001 | 11514900 |