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	Provedor de dados BJB (2) Autor RAGUSA-NETTO,J. (2) Palavra-chave Raptors (2) Alertness (1) Brazilian savanna (1) Emberizidae (1) Mixed flock (1) Nuclear species (1) Sentinel (1) Sentinels (1) Thraupinae (1) Mais... Tipo do documento Info:eu-repo/semantics/article (2) Ano 2001 (1) 2000 (1) País Brazil (2) Idioma Inglês (2)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 2 Primeira ... 1 ... Última Raptors and "campo-cerrado" bird mixed flock led by Cypsnagra Hirundinacea (Emberizidae:Thraupinae) BJB RAGUSA-NETTO,J.. Bird mixed flocks including Cypsnagra hirundinacea and Neothraupis fasciata as species with sentinels were studied in "campo-cerrado" in order to investigate the possible relationship between alertness and the mixed flock leadership. This study was conducted from March to September 1996 and mixed flocks were observed on average for 2:30h. The time with sentinels were recorded for C. hirundinacea and N. fasciata. The sentinels of Cypsnagra hirundinacea performed most of the vigilance (time with sentinel was on average 42 ± 17%, 41 ± 17% of which by C. hirundinacea, whereas only 1.2 % by N. fasciata) and gave all the alarm calls recorded (54% of the encounters with raptors stimulated alarm calls). A relationship was verified between time with sentinel and... Tipo: Info:eu-repo/semantics/article Palavras-chave: Mixed flock; Sentinel; Thraupinae; Raptors; Nuclear species. Ano: 2000 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0034-71082000000300011 Sentinels in Saltator atricollis (Passeriformes: Emberizidae) BJB RAGUSA-NETTO,J.. 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. Sentinels commonly gave contact calls in the beginning and/or at the end of a sentinel bout. The group size had no effect on time with sentinels. However the encounter rate between raptors and groups significantly influenced the time guarded. The results of this study suggests... Tipo: Info:eu-repo/semantics/article Palavras-chave: Emberizidae; Brazilian savanna; Raptors; Alertness; Sentinels. Ano: 2001 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0034-71082001000200015 Registros recuperados: 2 Primeira ... 1 ... Última

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